Megaprosthesis versus Allograft Prosthesis Composite for massive skeletal defects

Abstract

Massive skeletal defects are encountered in the setting of tumors necessitating excision, failed total hip arthroplasty with periprosthetic bone loss, periprosthetic fracture, complex trauma, multiple failed osteosynthesis and infection. Reconstruction of the segmental defects poses a tremendous challenge to the orthopaedic surgeons. The goal of osseous reconstruction of these defects is to restore the bone length and function. Currently the most commonly employed methods for reconstruction are either a megaprosthesis or an Allograft Prosthesis Composite (APC).

Megaprosthesis, initially created for the treatment in neoplastic pathologies are being used for the non-neoplastic pathologies as well. The longevity of these implants is an issue as majority of the patients receiving them are the survivors of oncologic issue or elderly population, both in which the life expectancy is limited. However, the early complications like instability, infection, prosthetic breakage and fixation failure have been extensively reported in several literatures. Moreover, the megaprostheses are non-biological options preventing secure fixation of the soft tissue around the implant.

The Allograft Prosthesis Composites were introduced to overcome the complications of megaprosthesis. APC is made of a revision-type prosthesis cemented into the skeletal allograft to which the remaining soft tissue sleeve can be biologically fixed. APCs are preferred in young and low risk patients. Though the incidence of instability is relatively low with the composites as compared to the megaprosthesis, apart from infection, the newer complications pertaining to APCs are inevitable that includes non-union, allograft resorption, periprosthetic fracture and potential risk of disease transmission.

The current review aims to give an overview on the treatment outcomes, complications and survival of both the megaprostheses and APCs at different anatomic sites in both the upper and lower limbs

1. Introduction

Massive skeletal defects are encountered in orthopaedic practice because of the bone loss due to tumor, infection, pseudotumor, osteolysis following joint replacement, complex fractures, and, failure of a megaprosthesis. The currently available solutions for the massive skeletal defects include either prosthetic implants (i.e., megaprosthesis) or skeletal allograft prosthesis composite (APC). Each of them have their own advantages and disadvantages.

The mega prostheses have been widely used since the evolution of limb salvage surgery in the late 1970s. The custom-made implants were being used before the development of modular prostheses and their use has been extended to replace the proximal humerus, distal humerus or an entire humerus in the upper extremity. Similar implants have been developed to replace the proximal femur, distal femur, entire femur, proximal tibia, distal tibia and entire tibia as well. Most of them are designed in such a way that the soft tissue sleeve is mobilised and directly fixed over the prosthesis. 1, 2 These reconstructions were insufficient due to the lack of muscle strength and subsequent instability of the adjoining joint leading to impaired function. ³ On the other hand, infection and loosening have remained as the main issues following reconstruction with the megaprosthesis.⁴

The Allograft Prosthesis Composites (APC) were introduced to reduce the complications of megaprostheses. The APC basically constitutes a revision type prosthesis inserted inside the skeletal allograft. The residual muscles and tendons can be attached to the allograft bone to purportedly reduce the risk of postoperative instability and provide better function.⁵ However, the APCs are also not devoid of complications. Periprosthetic bone resorption, non-union at the graft-host bone junction, fractures, infection and risk of disease transmission are the complications associated with this reconstruction method. ⁶

The megaprostheses implantations are easy but non-biologic procedures with limited longevity whereas reconstruction with allograft gives an advantage of osteoconduction but with inherent complications. The current review gives an overview of the treatment outcomes, complications and survival of each treatment modality for different anatomic sites in both the upper and lower limbs. At the end, we also discuss the merits of these two procedures by reviewing the recently available literatures comparing them. It is imperative to mention that megaprostheses are in use since a longer duration than the APCs which may be directly related to the availability of bone bank facility in the hospitals as well as the competence of the surgeons as the letter technique is demanding and requires a learning curve.

2. Megaprosthesis for massive skeletal defects

2.1. Upper limb

2.1.1. Proximal humerus

The reconstruction of the proximal humerus for massive bone defects depends on the type of resection as well the intactness of functional abductor system i.e. the rotator cuff and the deltoid muscle. Kassab et al. ⁷ advocated that if the resection removes the rotator cuff and the deltoid muscle (axillary nerve) then one can go either for a megaprosthesis or scapulohumeral arthrodesis. However, if the resection preserves the rotator cuff and/or the deltoid muscle, the reconstruction can be done with an allograft prosthesis composite and attaching the cuff muscles to the allograft bone. In their own study, Kassab et al. have mentioned that glenohumeral instability remains the most frequent complication following the reconstruction of proximal humerus which was seen in 37.9% of their 29 cases. The results of megaprosthesis in proximal end of humerus are affected by the fact that majority of the bone defects in the proximal humerus occur due to neoplastic lesions which are commonly seen in the paediatric patients who almost invariably require revisions. Although, the advancement in surgical technique and metallurgy have shown the improvement in functional outcome with the newer prostheses, the complications especially the neurovascular injuries, loosening of the component, instability and infection, and the need for repeated surgical procedures remain major challenges.⁸ The outcomes of use of megaprosthesis in different studies are summarized in Table 1.

Table 1.

Summary of the data from the recent studies on the use of megaprosthesis for the management of massive skeletal defects in proximal humerus.

Authors	Diagnosis	No of patients	Average age (years)	Average Follow up	Clinical outcome	Radiological Outcome	Complications	Result	Survival
Dubina et al.9	Tumors	761 (30 studies)	45	70.5	MSTS = 74%	–	17% mechanical failure* 4% infection	10% revisions	–
Schmolders et al.10	Primary tumors and metastasis	30 (15 with trevira tube)	41	26 m	EFS = 20	12 cranial migration of prosthesis	2 subluxations	3 revisions	83% at one year, 63% at 2 years
							1 luxation and infection
							1 RNP 1 recurrence 3 fractures
Marulanda et al.11	Malignancy	16 (Aortograft mesh)	51	26 m	–	–	1 superficial wound infection	1 death from disease	–

Abbreviations: EFS = Enneking Functional Score, RNP = Radial Nerve Palsy, m = months, *Mechanical failures including prosthetic loosening, fracture, and dislocation, CPS = Compliant Pre-stress Device, GH = Glenohumeral,PH = Proximal Humerus, SOH = Shaft of Humerus, DH = Distal Humerus.

Recent developments include silver-coated megaprosthesis to reduce the rate of infection and, trevira tube combined with the megaprosthesis to allow attachment of the remaining muscles and tendons by using fibre-wire sutures. Schmolders et al.¹⁰ found only one case of infection at a mean follow up of 26 months in their series of 30 patients treated with silver-coated megaprosthesis for proximal humeral reconstruction. Fifteen of the 30 megaprostheses were combined with trevira tube. Three patients (10%) had subluxation of which only one had to undergo a revision surgery. However, the authors failed to mention whether the subluxation occurred in the cases with trevira or without it. Marulanda et al.¹¹ used aortograft mesh to facilitate soft tissue attachment and provide mechanical constraint, and improve the stability of shoulder reconstruction following tumor resection. There was no incidence of shoulder dislocation reported in their series of 16 patients at a mean follow up of 26 months. Further, only one patient had a superficial wound infection and none had deep infection necessitating removal of the graft and/or the prosthesis.

2.1.2. Distal humerus and elbow

The distal humerus and the elbow joint are the uncommon sites for bone tumors or the metastasis. In majority of the cases, megaprostheses are indicated in the setting of failed previous arthroplasty, complex intraarticular fractures or failed osteosynthesis with bone loss. Arthrodesis is least acceptable in case of elbow. Although the survivorship of majority of the reconstruction options available is very much limited, the patients invariably want their elbow to be functioning to carry the activities of daily living. Also, successful reconstruction of the elbow gives more satisfaction to the patients.

Megaprostheses are required when even the conventional revision elbow prosthesis becomes insufficient to address the massive skeletal defects. Both modular as well as custom made prostheses have been described in the literature. However, there are only few published studies and majority of them are retrospective analysis with few number of subjects that too with broad spectrum of indications including both neoplastic and non-neoplastic conditions. The outcomes reported in different studies are summarized in Table 2.

Table 2.

Summary of the data from the recent studies on the use of megaprosthesis for the management of massive skeletal defects in distal humerus and elbow.

Authors	Diagnosis	No of patients	Average age (years)	Average Follow up	Clinical outcome	Radiological Outcome	Complications	Result	Survival
Goulding et a.12	Tumors and Failed TER	13 (CPS)	45	68 m	–	–	2 lack of CPS fixation (one breakage)	6 revisions	–
							2 loosening of ulnar component
		3 PH					1 bushing wear
		6 DH					1 infection
		1 SOH					2 GH subluxation
Capanna et al.13	31 Tumors	36	60.1	25 m	MEPS = 77.08	3 RNP	23 deaths from disease	93% at 5 years
	5 Failed				MSTS = 22.9	1 UNP	5-year survival = 25.1%
	TER					1 infection
						1 disassembly
Abdullah et a.14	2 Failed TER	3	–	6–24 m	DASH = 53.76	–	None had any complications	–	–
	1 Failed TER + SHA
Tang et al.15	Tumors	25	38.1	45.4 m	MSTS = 23.9	2 aseptic loosening of the ulnar component	4 revisions	11 deaths from disease	–
						2 aseptic loosening of the humeral component	4 recurrence
							2 nerve palsy and transient vascular compromise
Weber et al.16	Tumor and Failed TER/APC	23	46	46 m	MSTS = 23	5 stable Allograft	1 ulnar nerve transection	8 deaths from disease	–
		7 THRE				3 stable periprosthetic lysis around ulnar component	1 UNP	3 deaths unrelated to disease
		5 APC 11 TER				2 loosening of humeral component	1 RNP
							1 PINP
							2 infections

Abbreviations: m = months, TER = Total Elbow Replacement, MEPS = Mayo Elbow Performance Score, MSTS = Musculoskeletal Tumor Society Score, DASH = Disabilities of Arm Shoulder and Hand Score, RNP = Radial Nerve Palsy, UNP = Ulnar Nerve Palsy, THRE = Total Humeral Replacement Endoprostheis, APC = Allograft Prosthesis Composite, PIN = Posterior Interosseous Nerve, SHA = Shoulder Hemireplacement Arthroplasty.

Megaprosthesis using principle of compressive osteointegration have recently been introduced to enhance osteointegration by stable compression, preventing stress shielding and hence reducing the incidence of aseptic loosening. This technology involves compressing a porous-coated spindle at the implant-bone interface by a premeasured amount of force through washers and a traction bar, which in turn is secured in adjacent bone with pins. It has been used in cases with large osseous defects with remaining small segment of bone. Goulding et al.¹² retrospectively reviewed 13 such prostheses in 9 patients of which seven were implanted in distal humeri and two in proximal ulna. At a mean follow up of 68 months, six of them had to undergo revision-all after two years of surgery. Only two failures were attributed to fixation failure. The other failures were for bushing wear, aseptic loosening and infection.

2.2. Lower limb

2.2.1. Proximal femur

Massive bone loss in proximal femur is a complex condition which is usually seen both in neoplastic conditions following excision of bone tumors and metastasis, as well as in non-neoplastic conditions like failed arthroplasty, infection, complex trauma and periprosthetic fractures or multiple failed attempts at osteosynthesis. A large majority of these patients are young and are expected to live longer than the reconstruction thus requiring adequate bone stock for further revisions. The authors have an extensive experience of treating young patients with primary bone tumors and failed total hip arthroplasty with allograft prosthesis composites. On the other hand, patients with metastases, failed bipolar or unipolar hemiarthroplasty, multiple failed osteosynthesis and complex fractures in elderly are indications for megaprosthesis due to low demand and limited life expectancy with reduced likelihood of revision.

The historically used monoblock megaprostheses were initially replaced with custom made prosthesis and now with the modular ones. Most of the authors have reported the use of megaprosthesis at different sites in a single series. The outcomes of use of megaprosthesis in different studies are summarized in Table 3.

Table 3.

Summary of the data from the recent studies on the use of megaprosthesis for the management of massive skeletal defects in proximal femur.

Authors	Diagnosis	No of patients	Average age (years)	Average Follow up	Clinical outcome	Radiological Outcome	Complications	Result	Survival
Natarajan et al.17	Multiple Myeloma	6 (3 PF; 3 SF)	47.7	88.2 m	2 Excellent	One loosening	1 skin necrosis	2 deaths from disease	66.7% at 5 years
					2 Good		1 periprosthetic fracture
					2 Fair
Khan et a.18	Giant cell tumor	12	36	4.8 y	Mean clinical score of 28.3 (25–30)	No loosening No dislocation	2 superficial infections	All alive at latest follow up	–
Ilyas et a.19	Malignant tumors	15	37	6.7 y	MSTS = 19	One aseptic loosening	3 dislocations	3 revisions	–
							2 infections	2 deaths from disease
Bruns et al.20	Malignant tumors (23) & Non–neoplastic (22)	25 (7 PF)	40.1	2.5 y	MSTS = 24.9	11 stem stress shielding	2 extensor mechanism rupture	2 deaths from disease	87% at 7 years
					KI = 82%		1 DVT	1 revision
							1 Septic loosening
							1 dislocation of hip
Donati et al.21	Tumors	25 Malignant tumors (22), GCT (2), Osteoblastoma (1)	34	12.25 y	7	17 stem stress shielding	1 infection	4 revisions	–
					10 Good		1 dislocation
					7 Fair		1 stiff knee
					1 Poor		1 recurrence of disease
Bernthal et al.22	Sarcomas	24 (7 PF, 9 DF, 8 PT)	37	13.2 y	MSTS = 25.9	–	–	All walking without aids	–
Shih et al.23	Failed THA with massive bone loss	12	59	5.7 y	HHS = 83	1 HO	5 dislocations	2 revisions 3 Girdle stone arthroplasty	–
						3 GT displacement	4 infections
						1 aseptic loosening
Donati et al.24	Primary or metastatic tumors	68 (38 SC, 30 UC)	61.6	46.5 m	–	–	4	14 re-surgeries	–
							8 infections
							2 relapse
Ahlmann et al.25	Bone neoplasia	211 (96PF, 78 DF, PT 30, TF 7)	50	37.3 m	MSTS = 22.25	5 Aseptic loosening	9 Fatigue failure	29 revisions, 5amputations	60% at 10 years
					PF = 22		11 Infections
					DF = 22.9	DF 4	6 recurrence (PF 3, DF 2, PT 1)
					PT = 22.25	PT 1	10 dislocations	97.6% limb survival at 10 years	PF 82%
					TF = 19.5		1 Fracture		DF 58%
									PT 82%
									TF 100%
Bertani et a.26	Tumors and Non-neoplastic conditions	23 (13 Tumors, 8 Failed THA, 2 Trauma)	65 ± 17.2	5.4 y	MSTS = 16.2	1 Aseptic loosening	2 infections	5 revisions	81.5% at 10 years
							1 tumor extension
							1 stem fatigue fracture
Calabro et al.27	Malignant Tumors (7 failed previous prosthesis)	109 95 cemented 14 cementless	60	2.5 y	MSTS = 21	–	5.8%infection	6 deaths from disease	74% at 9 years
							3.9%dislocation
							2.9%recurrence
							1%acetabular fracture
Calori et al.28	Non-union, Complex Fractures and Failed THAs	32 (11 PF, 13 DF, 2 PT, 6 TF)	64	18 m	–	–	1 dislocation	–	–
							1 fracture (DF)
Curtin et al.29	Periprosthetic fractures	16	75	19.2 m	OHS = 39	–	2 dislocations	–	–
Hardes et al.30	Sarcomas	125	37	19 m 54 m	–	–	Infection	Revisions	–
							5.9%
	55 PF	22 SC + 23 UC					17.6%
	70 PT	SC + 41 UC					PF: 4.5 vs 18.2%	9 vs 9 %
							PT: 6.9 vs 17.1%	3 vs 32 %
Ji et al.31	Tumors	7 (3 PF, 1 DF, 2 PT, 1 Patella)	28	27 m	MSTS93 = 81%	–	1 local recurrence	1 revision	–
Korim et al.32	Non-neoplastic conditions	356 14 studies		3.8 y (0–14)	–	2.5 % loosening			83% implant retention
							7.6% infection	12 % mortality
							0.5% prosthesis fracture
							1 % periprosthetic fracture
Lundh et al.33		17	77	44 m	–	–	3 infections	9 deaths at latest follow up	94% at 44 months
	2 CF Knee	5 PF					2 dislocations
	10 PPF Knee	8 DF
	5 PPF Hip	2 TF
		2 Primary prosthesis
Hattori et al.34	Metastasis		61.8	2.5–86 m	MSTS = 62.3%		2 dislocations	1 revision	86.4 % at 6 months
		19 PF
		2 IC
		1 TKA
Gosal et a.35	GCT	11	32	10.6 y	MSTS = 26.8	–	–	–	100%
Parvizi et al.36	Non- Neoplastic conditions	48	73.8	36.5 m	HHS = 64.9	2 radiolucencies >2 mm	8 dislocations	10 revisions	87% at 1 year
							1 infection		73% at 5 years
							4 acetabular failure
Ruggieri et al.37	Sarcomas	23	21	148 m	MSTS = 66%	–	1 Leg ischemia	5 revisions	38% disease free at 16 years
							1 infection	13 deaths from disease
							1 prosthetic disconnection
							1 poly wear
							1 PPF
Mazurkiewicz et al.38	Primary neoplasms and metastasis	49	–	–	28% excellent	–	3 dislocation	2 deaths from disease
					60% good		1 infection
		12 primary					1 recurrence
		37 metastasis
Ueda et al.39	Periacetabular tumors	25	44	163 m	MSTS = 55%	2 aseptic loosening	8 infections	5 revisions	47% at 5 years as well as at 10 years
							4 dislocations	13 deaths from disease
							7 local recurrence	1 hemipelvectomy
								3 implant removal
Tan et al.40	Tumors	17 (4 PF, 7 DF, 6 PT)	–		MSTS = 78.3% ± 16.6%	–	7 infections		75.6 months implant survival
							2 dislocations
							1 CPN palsy

Abbreviation: PF = Proximal Femur, SF = Shaft of Femur, DF = Distal femur, TF = Total Femur, PT = Proximal tibia, MSTS = Musculoskeletal Tumor Society Score, KI = Karnofsky Index, DVT = Deep Vein Thrombosis, GCT = Giant Cell Tumor, THA = Total Hip Arthroplasty, HHS = Harris Hip Score, HO = Heterotopic Ossification, SC = Silver Coated, UC = Uncoated, OHS = Oxford Hip Score, m = months, y = years, CF = Comminuted Fracture, PPF = Periprosthetic Fracture, IC = Intercalary, TKA = Total Knee Arthroplasty, CPN = Common Peroneal Nerve.

Despite the ease of reconstruction for restoring the structural deficiency with megaprostheses, complications are encountered similar to those with other anatomic sites. One of the most frequent complication is dislocation. The higher incidence of dislocation is attributed to the inability to secure the residual soft tissue to the metal prosthesis .⁴¹ Ueda et al.³⁹ used constrained Total Hip Megaprosthesis to achieve the ilio-femoral stabilization and reduce the risk of hip dislocation. Postoperative dislocation was seen in only 4 of their 25 patients treated with constrained megaprostheses following excision of the periacetabular tumors. The use of constrained liners may decrease the incidence of dislocation; however, the authors caution regarding the problems with the use of constrained liners like aseptic loosening of the acetabular component and the catastrophic failure in osteoporotic elderly patients. Nowadays, with the availability of larger heads and dual mobility cups, the use of constrained liners may be reduced. Infection remains the other major problem. The use of sliver coated megaprostheses as mentioned in the literature is supposed to reduce the rate of infection because of the antimicrobial activity of the silver.⁴² Hardes et al.³⁰ compared the infection rate in 51 patients implanted with silver coated megaprostheses (22 proximal femur and 29 proximal tibia) with 74 patients in whom uncoated Titanium megaprostheses (33 proximal femur and 41 proximal tibia) were used for bony reconstruction following excision of sarcomas. At the mean follow up of 54 months, the infection rate was found to be substantially low in the silver group (5.9%) as compared to the Titanium group (17.6%). The infection rate in proximal femoral megaprosthesis alone was 4.5% in the silver coated group and 18.2% in the uncoated group. Periprosthetic fracture and/or the prosthetic breakage and subsequent implant failure remains the other problem with these expensive megaprostheses. Parvizi et al.³⁶ advocated that the prerequisite for a successful proximal femoral replacement is the length of the distal part of the femur. An adequate length is required to obtain a secure fixation of the femoral stem. If the distal bone is severely deficient then it is better to go for a total femoral replacement by sacrificing the remaining bone rather than going for a proximal femoral reconstruction alone.

2.2.2. Distal femur

Primary bone tumors, benign as well as malignant are commonly seen around the knee especially at the distal end of femur which is the one of the common site for metastasis as well. Being a weight bearing bone, reconstruction of the distal femur following excision of the tumors is of utmost importance. With modern day effective treatment using neo-adjuvant and adjuvant chemotherapy, limb salvage is the recommended treatment for tumors wherever possible. Various reconstruction options are available for the reconstruction of distal femur following tumor excision that includes arthrodesis, osteoarticular allograft, rotationplasty, megaprosthesis and allograft prosthesis composite. Because of the accessibility and ease of insertion, megaprosthesis are commonly being used. The other indications for the use of megaprosthesis are failed total knee arthroplasty with massive bone loss, periprosthetic fractures, persistent non-union despite multiple surgeries and comminuted intra-articular fractures in elderly with significant bone loss. The megaprostheses offer early mobility with maintenance of joint motion in these cases. The modern modular megaprostheses have replaced the previously used custom made prostheses. The megaprostheses have been available both with cementless as well as cemented stems. Both fixed and rotating hinge megaprostheses are being used these days as the salvage option in the distal femoral reconstruction for massive skeletal defects. The outcomes of use of megaprosthesis in different studies are summarized in Table 4.

Table 4.

Summary of the data from the recent studies on the use of megaprosthesis for the management of massive skeletal defects in distal femu.

Authors	Diagnosis	No of patients	Average age (years)	Mean Follow up	Clinical outcome	Radiological Outcome	Complications	Result	Survival
Agarwal et al.43	Osteosarcoma	135 (92 megaprosthesis)		32.4 m	EFS	3 loosening	8 infections	5 revisions	61% disease free survival at latest follow up
		49 DF, 22 PT, 14 PH, 3 PF, 3 TH, 1 DH)					1 limb ischemia	3 amputations
					LE = 85%		4 PPF	1 hip disarticulation
					UE = 66%		3 implant breakage	2 implant removal
							2 recurrences
							2 CPN palsy
							1 RNP
Bruns et al.44	Malignant tumors (23) & Non-neoplastic (22)	25 (13 PF, 5PT, 7 PF)	40.1	2.5 y	MSTS = 24.9	11 stem stress shielding	2 extensor mechanism rupture	2 deaths from disease	87% at 7 years
					KI = 82%		1 DVT	1 revision
							1 Septic loosening
							1 dislocation of hip
Ilyas et al.45	Tumors	48	24	5.6 y	MSTS = 21	2 aseptic loosening	6 infections	1 amputation	65% at 10 years
							2 SNP	1 recurrence
							CPN palsy	7 deaths from disease
							21 limb ischemia
							1 prosthetic fracture
							1 prosthetic fracture
							1 PPF
Pala et al.46	Tumors	247 (187 DF, 60 PT)	32	2 y	MSTS = 81%	14 aseptic loosening (5.7%)	23 infection (9.3%)	24 deaths from disease	70 % at 4 years, 58 % at 8 years
							14 recurrence (5.7%)
Toepfer et.47	Tumors &	129(82 reviewed)				15 aseptic loosening (20%)	17 soft tissue failure (22.7%)	47 deaths from disease	81.8 ± 7.3 months implant survival
	Failed Revision TKA	36 available		86m			28 structural failure (37.3%)	64.6% overall failure
		20 Tumors					13 infections (17.3%)
		16 Failed rTKA	46.2 ± 22.1		MSTS = 17		2 recurrences
			71,0 ± 13,3		MSTS = 12
Biau et al.48	Tumors	91 (58 MP, 33 APC)	27	62 m	–	18 aseptic loosening (20%)	10 failures 8 failures	23 deaths
		56 DF						21 revisions	130 m
		35 PT						15 revisions	117 m
Ahlmann et al.49	Diaphyseal tumors	6 ICEP	42	21.6	MSTS =  90%	1 loosening of humeral prosthesis	1 humeral revision	All doing well	100% at one year 83% at 2 years
		3 Tibia
		2 Femur
		1 Humerus
Cannon50	PPF of Distal Femur	27	–	6 m	KSS = 88	–	1 infection	8 deaths unrelated to disease	–
							1 delayed wound healing
Chim et a.51	Tumors	10 (5 DF & 5 PT)	31	32 m	–	–	1 infection	3 metastases and deaths	–
							1 superficial skin necrosis
							1 cellulitis (All resolved)
							4 recurrence
Evans et al.52	Trauma	10	70.2	3 y	TESS = 62.5	No loosening	All doing well	1 death unrelated to surgery	–
Gosheger et al.53	Sarcomas	250	30.7	45 m	EFS:	20 aseptic loosening (8%) 2	30 infections (12%)	47 deaths due to disease	Prosthetic survival
		39 PH				cranial subluxation of humeral prostheses	4 prosthetic fracture (1.6%)		60.4% at 5 years
		5 DH					3 femoral dislocations		42.3 % at 10 years
		7 TH			PH = 21		8 poly wear
		41 PF			DH = 23		1 Patellar tendon avulsion
		103 DF			TH = 19
		12 TF			PF = 21
		42 PT			DF = 24
		1 TT			TF = 20
					PT = 25
Holl et al.54	Failed TKA	20 (21 Knees)	73	34 m	KSS = 68	2 aseptic loosening	6 infections	2 revisions 1 non-salvage	–
		15 DF					2 PPF	2 deaths due to infection
		4PT
		2 Both DF & PT
Hu et al.55	Neoplasm and non-neoplastic conditions		40.3	89 m	MSTS = 25.2	5 loose cemented stems	5 prosthetic fracture	13 deaths from disease	91% at 2 years 83% at 5 years 68 % at 10 years
						3 asymptomatic radiolucencies	7 uncontrolled infections	17 deaths unrelated to surgery
							3 tumor progressions	10 amputations
Kinekl et al.56	Tumors	77 (49 DF, 28 PT)	38	46 m	EFS = 73%	13 aseptic loosening	15 locking mechanism failure	58% revision rate	57% at 5 years
							11 infections	8 implant removal
							4 recurrence	5 amputations
							3 PPF1 patellar tendon rupture
							5 joint stiffness
							10 wound problem
Pala et al.57	Tumor	687	34	7.9 y	MSTS = 23.3 (77.6%)	33 aseptic loosening	41 soft tissue failure	Over all 27 % failure rate 206 deaths from disease	70% at 10 years 50% at 20 years
							26 structural failure (fixed prostheses only)
							57 infections
							28 recurrence
Staals et.58	Malignant tumors of distal femur	15 (Expandable prosthesis)	8	104 m	MSTS =  81%	1 loosening	8 breakage	9 revisions & deaths	–
							2 recurrence	2 amputations
							1 infection	2 deaths due to metastasis
								No longer use by authors
Vincent et al.59	–	196 (DF & PT)	–	–	–	–	Cemented (29):	45 revisions	–
		109 cemented					62% loosening
		87 press fit					24% infection
							13% fracture
							Press fit (16):
							43% loosening
							31% infection
							6% fracture
							6% LLD
							6% recurrence
							6% malrotation
Torner et al.60	Tumors	7 (6 DF, 1 PF) (Expandable prosthesis)	9.8	65.3 m	MSTS = 26.3	–	1 pelvic metastasis	2 deaths from disease	71.5% success rate (5 out of 7 functioning well at latest follow up)
							1 implant failure due to MRI done for leg trauma
Vaishya et al.61	Resistant non-unions of DF fractures	10	74	4 y	KSS (pain) = 84 KSS	–	3 wound problems	–	–
					(function) = 88		1 PPF
Zimel et al.62	Failed distal femoral prosthesis	27 Compliant Pre-stress Implant	30	90 m	MSTS = 27	–	3 mechanical failure	2 revised to CPC	–
								1 revised to APC
								3 amputation
							4 infections	1 fusion
Windhager et al.63	PPF	144 (seven studies)	68.4–81	6–58.6	–	–	20 mechanical failures	0–55% revisions	–
							23 non-mechanical failures	6.6–45% mortality

Abbreviations: PH = Proximal Humerus, TH = Total Humerus, DH = Distal Humerus, PF = Proximal Femur, DF = Distal Femur, TF = Total Femur, PT = Proximal Tibia, TT = Total Tibia, EFS = Enneking Functional Score, LE = Lower Extremity, UE = Upper Extremity, m = months, PPF = Periprosthetic fracture, CPN = Common Peroneal Nerve. RNP = Radial Nerve Palsy, MSTS = Musculoskeletal Tumor Society score, KI = Karnofsky index, SNP = Sciatic Nerve Palsy, TKA = Total Knee Arthroplasty, rTKA = Revision Total Knee Arthroplasty, MP Megaprosthesis, APC = Allograft Prosthesis Composite, EMF = Extensor Mechanism Failure, ICEP = Intercalary Endoprosthesis, KSS = Knee Society Score, TESS = Toronto Extremity Salvage Score, MRI = Magnetic Resonance Imaging

2.2.3. Proximal tibia

The indications for the proximal tibial megaprosthesis remain the same as for the distal femur viz a critical bone defects of neoplastic, traumatic or prosthetic origin. However, the reconstruction of extensor mechanism is a great challenge, failure of which may lead to extensor lag and resultant poor knee function. The outcomes of use of megaprosthesis in different studies are summarized in Table 5.

Table 5.

Summary of the data from the recent studies on the use of megaprosthesis for the management of massive skeletal defects in proximal and distal tibia.

Authors	Diagnosis	No of patients	Average age (years)	Average Follow up	Clinical outcome	Radiological Outcome	Complications	Result	Survival
Titus et al.64	Tumors	10	48	4 y	MSTS = 82%	–	2 CPN Palsy	4 deaths from disease	60% living without disease
							2 infections
							2 Quadriceps adhesions
							6 cerclage wire break
Calori et a.65	Post traumatic septic bone defects	9	68	18 m	WOMAC = 74.8	No loosening	–	No recurrence of infection	100% survival at 18 months
								No revision
								Excellent result
Cho et al.66	Tumors	62	26	98 m	MSTS =  24.2	–	16 infection	3 amputation	73.9 ± 11.7% at 10 years
		RH- 44					1 recurrence	8 arthrodesis
		Fixed = 18
Hardes et al.67	Tumors	98			–	–	Infection	Revision	At 5 years
		SC- 56	SC = 19	SC = 38 m			SC = 8.9%	SC = 14.3%	SC- 90%
		UC(Ti) = 42	UC = 16	UC = 128 m			UC = 16.7%	UC = 50%	UC=84%
Yang et al.68	Aggressive tumors of distal tibia	8	33	77 m	MSTS =  66%	1 aseptic loosening	2 infections	2 deaths from disease	63% at 5 years
									42% at 10 years

Abbreviations: m = months, MSTS = Musculoskeletal Tumor Society Score, WOMAC = Western Ontario & McMaster Universities Osteoarthritis Index, RH = Rotating Hinge, FH = Fixed Hinge, SC = Silver coated, UC = Uncoated, Ti- Titanium.

Titus et al.⁶⁴ described their own technique of reattachment of the ligamentum patellae to the porous tibial tuberosity of the proximal tibial megaprosthesis, and protecting the repair with a cerclage wire through the patella and the prosthesis. In their consecutive 10 cases of reconstruction with the same technique they had only one case of ligament avulsion at mean follow up of 4 years. Calori et al.⁶⁵ reconstructed the patellar tendon by lengthening the fibres of quadriceps tendon or its fascia, or patellar tendon itself, or medial gastrocnemius flap in nine cases who required patellar tendon reconstruction along with proximal tibial megaprosthesis for post-traumatic septic bone defects. Only one patient presented with rupture of the reconstructed patellar tendon due to fall at 18 months following the surgery. The current authors have also described their own technique of reconstruction of extensor mechanism with composite allograft consisting of a patella– patellar tendon–tibial tubercle.69, 70 In our series of 5 patients (4 with TKA and 1 GCT Patella), all of them are functioning well till the latest follow up of 10 years.

Apart for the problems with extensor mechanism following megaprosthetic reconstruction around the knee, infection remains the major issue as it is with other sites. The silver coated megaprosthesis are also available for knee reconstruction to reduce the incidence of infection.⁶⁷ Chim et al.⁵¹ mentioned that the use of primary muscle flap to cover the megaprostheses following limb salvage surgery will decrease the infection rates. Pala et al.⁵⁷ compared the results of fixed and rotating hinge knee prosthesis for reconstruction of distal femoral defects and found that there was no significant difference in implant failure due to aseptic loosening and infection between the two types of prostheses. Hu et al.⁵⁵ compared the survivorship of cementless and cemented diaphyseal fixed modular rotating- hinged knee megaprosthesis. They found that the survivorship of the cementless fixed component (94% at 5 years) was significantly superior to that of cemented fixed stem (75% at 5 years). In patients with residual minimal bone for stem fixation the newer prostheses that uses the principle of compressive osteointegration have proven low rate of mechanical failure at a follow up of 10 years.⁶² However, the ultramodern designs of using the expandable prostheses have gained little importance because of the requirement of multiple surgeries and high complication rates.58, 60 Staals et al.⁵⁸ cautioned against their use due to very high revision rate where 9 of his 10 survivors required revision of the implant for mechanical failure.

2.2.4. Distal tibia

Reconstruction of distal tibia for massive defects due to any etiology is for restoring the ankle function. There are very few cases of megaprosthetic reconstruction of distal tibia reported in the literature.⁶⁸ This may be probably due to the limited longevity of megaprosthesis along with its inherent complications. The treatment modality may not be beneficial over ankle arthrodesis. The authors have no experience of using a distal tibial megaprosthesis as a method of reconstruction for massive skeletal defect.

3. Allograft prosthesis composite for massive skeletal defects

3.1. Upper limb

3.1.1. Proximal humerus

Allograft Prosthesis Composite (APC) is an alternative option for limb reconstruction for massive skeletal defects of the proximal humerus. The composite is a favorable choice that addresses the reconstructive challenges of restoring the bone stock and reconstructing the soft tissue sleeve meant for providing the stability to the joint. The soft-tissue attachments especially the rotator cuff muscles can be attached to the allograft bone of the composite and provide a stable functional construct. The outcomes of use of Allograft Prosthesis Composite in Proximal humerus as reported in different studies are summarized in Table 6.

Table 6.

Summary of the data from the recent studies on the use of Allograft Prosthesis Composite for the management of massive skeletal defects in proximal humerus.

Authors	Diagnosis	No of patients	Mean age (years)	Average Follow up	Clinical outcome	Radiological Outcome (loosening/HO)	Complications	Result	Survival
Ruggieri et.71	Gorham’s disease	14	35	25 m	MSTS = 77 %	–	2 allograft fracture	2 revisions	–
							1 infection and fracture
							1 locking mechanism failure
							1 infection
							1 allograft fracture
							1 locking mechanism failure
Abdeen et al.72	Osteosarcoma(19), chondrosarcoma(8),oligometastasis(3), others(6)	36	23	5 y	MSTS = 26	5 superior migration of the humeral head	1 dislocation	3 revisions	88% at 10 years (construct survival)
							4 delayed union
						3 loosening
						3 prosthetic osteolysis
Gharedaghi et al.73	Bone tumors	102	24.5 ± 5.39	2 y	–	–	6 Non-union	–	–
		8 Pelvis					6 allograft fracture
		12 PF					8 infection
		18 SOF					6 Local recurrence
		36 DF					11 metastasis
		12 PT					48 limited knee ROM
		16 humeri
Black et al.74	Malignant bone tumors	6	40.7 years	Initial = 25.2y	MSTS = 74%	–	1 non-union	–	–
				Second = 55y			1 implant failure
Chacon et al.75	Patient treated with Reverse shoulder arthroplasty	25	–	30.2 m	ASES = 69.4	1 Metaphyseal resorption	2 dislocation	–	–
						2 Fragmentation	1 allograft fracture
						1 Diaphyseal Resorption	1 non-displaced acromion fracture
						4 Non-incorporation
Dudkiewicz et al.76	Osteosarcoma	11	17–74	–	–	–	2 non-union	1 death from diseae	–
							2 infections
							1 recurrent instability
Kassab et al.7	Malignant bone tumors	29	–	85 m	MSTS = 72.6% massive prosthesis		11 GH instability	–	–
Lazerges et a.77	Tumors	6	65.5	5.9 y	MSTS = 73%	2 glenoid notches visible	1 recurrent instability	1 revision	–
	(Reverse APC)				QDASH = 41		1 non-union	1 death from disease
Potter et al.78	Tumors	49	48.5	98 m	MSTS:			DFD:	At 5 years
		17 OAG			OAG = 71%	–	OAG = 65%	OAG = 7	OAG = 56%
		16 APC			APC = 79%		APC = 44%	APC = 6	APC = 91%
		16 MP			MP = 69%		MP = 44%	MP = 12	MP = 100%
Teunis et al.79	Tumors	693 (616 studied)	Sep-57	Minimum 2 y	FS:	–	Per patient,	–	At 5 years
	(29 studies)	143 OAG
		132 APC			OAG=50–78%		OAG = 0–150%		33–100%
		341 MP			APC=57–91%		APC = 19–79%		33–100%
					MP=61–77%		MP = 4.5–85%		38–100%
Wang et al.80	Tumors	25		48 m	MSTS:	5 allograft resorption	10 instability and subluxations	2 deaths from disease	–
		12 OAG			OAG = 24.58	3 MP fractures
		7 APC			APC = 27.00
		7 MP			MP = 22.50

Abbreviations: m = months, y = years, MSTS = Musculoskeletal Tumor Society Score, ASES Score = American Shoulder and Elbow Surgeons Score, PF = Proximal Femur, SOF = Shaft of Femur, DF = Distal Femur, PT = Proximal Tibia, QDASH = Quick Disabilities of Arm Shoulder and Hand, OAG = Osteoarticular Allograft, APC = Allograft Prosthesis Composite, MP = Megaprosthesis, DFD = Deaths from Disease, FS = Functional Score.

Although the attachment of soft tissue sleeve to the allograft bone improve the function, the ultimate result depends on the extent of resection and muscle sacrifice as the rotator cuff muscles are often sacrificed especially in case of tumors. This leads to insufficient abductor action, and hence the instability and poor shoulder function. Reverse shoulder arthroplasty which was introduced to treat the arthritic shoulder with rotator cuff arthropathy operates through the action of remaining deltoid muscle. Nowadays, the reverse shoulder prosthesis is being combined with the allograft with purported advantage of improvement in the function. Lazerges et al.⁷⁷ reported a series of 6 cases treated with composite reverse shoulder arthroplasty following excision of malignant tumors of the proximal humerus. At a mean follow up of 5.9 years, there was only one case of dislocation requiring revision. Quick Disabilities of Arm Shoulder and Hand (DASH) score improved from 28 to 41 and the VAS score improved from a mean of 5.1 to 2.3. The mean Musculoskeletal Tumor Society Score (MSTS) was 73% at the latest follow up and the mean satisfaction score was 8.1/10. Chacon et al.⁷⁵ used this reverse shoulder allograft-prosthesis composite for revision of failed shoulder hemireplacement arthroplasty. At an average follow up of 30.2 months, the mean American Shoulder and Elbow Surgeons (ASES)score improved from 31.7 to 69.4 Nineteen patients (76%) reported a subjective good to excellent result. The range of motion improved in all the planes.

3.1.2. Distal humerus and elbow

Elbow being the less common site for primary tumors and malignancy, most of the APCs are used for salvage of failed previous total elbow arthroplasties or failed union following trauma. The outcomes of use of APCs around the elbow as reported in different studies are summarized in Table 7.

Table 7.

Summary of the data from the recent studies on the use of Allograft Prosthesis Composite for the management of massive skeletal defects in proximal humerus.

Authors	Diagnosis	No of patients	Average age (years)	Average Follow up	Clinical outcome	Radiological Outcome	Complications	Result	Survival
Mansat et al.81	Failed TER	13	62	42 m	MEPS:	–	4 infections	5 revisions	–
					4 Excellent		2 non-unions	3 APC removal
					3 Good
					1 Fair
					5 Poor
Amirfeyz et al.82	Failed TER	10 (11 elbows)	64	75 m	MEPS = 74	3 partial resorption in humeral side	1 infection	1 APC removal	–
		8 humeral APC				4 partial resorption in ulnar side
		6 Ulnar APC
Morrey et al.83	22 Failed TER	25	60	3.4 y	MEPS = 84	92% incorporated with host bone	3 infection	9 reoperations	–
	1 Failed hemiarthroplasty						3 fractures
	1 resection arthroplasty						1 non-union	4 resection arthroplasty
	1 non-union						1 malunion
Renfree et al.84	5 failed TER	10 (14 APCs)	58	6.5 y	BMES = 20	79% incorporated	1 infection	4 allograft related failures	–
	3 humeral non-union				HSSES = 37		1 non-union
	1 Ulnar non-union					1 complete resorption of olecranon
	1 OM proximal ulna

Abbreviations: m = months, y = years, TER = Total Elbow Arthroplasty, MEPS = Mayo Elbow Performance Score, OM = Osteomyelitis, BMES = Bryan-Morrey Elbow Score, HSSES = Hospital for Special Surgery Elbow Score.

3.2. Lower limb

3.2.1. Proximal femur

The reconstruction options for massive proximal femoral bone loss are limited either to a megaprosthesis or an allograft prosthesis composite. The indications for the use of megaprosthesis and their results in different studies have already been discussed in previous section. While the megaprosthesis allows early weight bearing and hence, a superior early outcome, Allograft Prosthesis Composites have shown improved functional outcome and implant survival and therefore a superior long-term outcome. The outcomes of use of APCs around the proximal femur as reported in different studies are summarized in Table 8.

Table 8.

Summary of the data from the recent studies on the use of Allograft Prosthesis Composite for the management of massive skeletal defects in proximal femur.

Authors	Diagnosis	No of patients	Average age (years)	Average Follow up	Clinical outcome	Radiological Outcome	Complications	Result	Survival
Biau et al.85	Tumors	32	41	68 m	–	–	9 revisions; 5 for mechanical reasons and 4 for infection	14% revision at 5 years, 19 % revision at 10 years	–
McGoveran et al.86	Tumors	16	51	47 m	TESS = 71.2 (37.0 to 91.0)	–	3 infection	Poor functional scores	–
							3 fracture
							2 non-union
							1 delayed union leading to fracture
Babis et al.87	Failed THA	72	59.9	12 y	HHS = 73 (52 to 85)	Aseptic loosening in 4	19 revisions;	14 died	69% at 10 years
							infection 5	19 revised
							loosening 4
							fracture 4
							non-union 2
							stem fracture 1
							resorption 3
Biau et al.88	Tumors	18	–	83 m	TESS = 76	1 loosening	4 infection	10 revision	–
					HHS = 90		5 removal
					PMAS =		1 aseptic loosening
					PCSS = 44
					MCSS = 49
Chen et al.89	Tumors	10 PF	37.9	43 m	EFS = 80%	–	1 sciatic nerve palsy	1 died	–
		2 DF						No revision
		2 PH
		(Autograft Prosthetic composite)
Chen et al.90	Tumors	14 (Autograft Prosthetic composite)	28.1	65.7 m	EFS = 72.1%	–	1 non-union	3 died	85 % at 5 years
Clarke et al.91	1 Malignancy	11	59	49 m	6 patients had no or slight pain on pain score	2 loosening	2 infection	5 revision	61% at 5 years
	5 Arthritis
	5 DDH
Donati et al.92	Tumors	27	32	58 m	MTSS excellent in 73%, good in 18 % and fair in 9 %	–	1 non-union	3 revision	–
							1 fracture
							1 infection
Dubory et al.93	14 Failed THA	46	34.3	14.7 y	PMAS = 15.7 (8 to 21)	12 loosening	2 infection	2 died	Over all 54.1% at 10 year
	32 Malignancy				MTSS =  77% (15 to 29)			51 re - operations	81.4 % femoral stem
Eid et al.94	Tumors	18	39	93 m	MSTS = 80%	1 loosening	2 infection	6 re-operations	86% at 5 and 10 years
Groundland et al.95	Tumors	PF 5 studies	13.5 to 14.5	54.3 to 69.7 m	MSTS = 71 to 86.8 %	–	Loosening and infection most common complications	Failure rate of APC less than MPs at PF and more than MPs at DF and PT	–
		DF 4 studies
		PT 4 studies
Langlias F et al.96	Tumors	21	38	10 years	MSTS = 77 %	4 loosening	No infection	8 re-operations	81 % at 10 years
						4 non-union	No dislocation
Lee S H et al.97	Total Hip Replacement	15	60.9	4.2 year	HSS = 83.2	1 non-union	1 infection	3 re-operations
						2 loosening	1 dislocation
Malhotra R et al.98	Giant Cell Tumors	18	32	54 months	HHS = 91 in 13 pt	–	No infection	No re-operation	–
					HHS = 86 in 5 pt		No loosening
Min L et al.99	Tumors	28	–	56 m	MSTS = 26.5	–	No infection	3 died	–
					HHS = 80.6		3 non-union	1 re-operation
							1 fracture
Lee Y S et al.100	Tumors	142 pasteurized autograft prosthesis composite for PF, DF, PH	24	110 m	–	–	–	–	78 % at 20 year for PF
									65 % for DF
									34.7 % for PT
									46.9% for PH
Ye ZM et al.101	Tumors	12 PF	–	64 m	EFS = 23.4	No loosening	No dislocation	3 died	–
		10 DF
		3 PT
Wang J W et al.102	Failed THA	15	58.7 y	7.6 years	HHS = 81 in 10 patients that retained prosthesis		1 Fracture	5 APC removed and 2 re - implanted	–
							2 Non-union
							3 Infections
Sternheim A et al.103	Failed THA in Dysplastic hips	30 hips in 28 patients	58.1 years	15 years	HHS = 67.6	5 loosening	1 infection	6 revision	93% at 10 yr, 75.5 % at 15yr, 75.5 % at 20 yr
Sternheim A et al.104	Failed APC after revision THA	21	64 years	96 months	HHS = 57	1 loosening	2 non-union	–	83.5 % at 5 and 10 year
Subhadrabandhu S et al.105	Tumor	10 PF	36 years	63 months	MSTS = 89.3%	–	1 fracture	–	–
		5 DF					2 infection
		4 PT
		1 PH
		1 PR
		1 Hemipelvis

Abbreviations: m = months, y = years, THA = Total Hip Arthroplasty, TESS = Toronto Extremity Salvage Score, PMAS = Postel and Merle d’Aubigne ´ score, PCSS and MCSS = Physical Component Summary Score and Mental Component Summary Score as a part of Short Form 36 (SF-36) score, EFS = Enneking Functional Score, MP = Megaprosthesis, PF = Proximal Femur, DF = Distal Femur, PT = Proximal Tibia PR = Proximal Radius.

Allograft Prosthesis Composites are indicated in younger patients. In addition to the restoration of bone stock by the allograft, the APC allows attachment of the gluteus and iliopsoas tendon thereby preventing instability. The allograft is combined with a long cementless revision stem to make a composite where the proximal part is cemented and the distal part is left as it is to obtain osteointegration with the host bone. The immediate stability is provided by the step cut osteotomy made in the host bone and the reciprocal osteotomy over the adjoining allograft. The permanent stability is achieved after union of the allograft to the host bone.

There have been studies regarding the use of Autograft Prosthetic Composite following Extracorporeal irradiation of the resected segment and reimplantation with a conventional arthroplasty. Chen et al.⁸⁹ reported the use of Proximal Femoral Autograft Prosthesis Composite in 10 of his 14 patients following resection of tumor. There were no complications like infection, fracture or non-union. There was 100% union at the host-irradiated bone junction within 8 months. Another similar study.⁹⁰ using extensively porous coated stem for constructing the Proximal Femoral Autograft Prosthetic Composite in 14 patients showed that the union was achieved in 12 patients at a mean of 20.3 weeks. There were no major complications reported. The authors suggested that this technique could be a reliable method of managing the massive bone loss in oriental countries where the availability of obtaining allograft is an issue.

The Allograft Prosthesis Composites have been currently favored by many over the other reconstruction techniques.87, 98, 99, 100 However, the problems like infection, non-union, allograft resorption, periprosthetic fracture and risk of disease transmission continue as major issues. The ultimate outcome depends on the etiology (i.e. neoplastic or non-neoplastic), intactness of soft tissue, size of defect, method of reconstruction, and preparation of the allograft. The patients’ characteristics such as age at presentation, gender, and occurrence of a pathologic fracture plays an important role in determining the function, disability, and health-related quality of life following allograft-prosthesis composite reconstruction of the proximal femur.⁸⁸

3.2.2. Distal femur and proximal tibia

Distal Femur and Proximal Tibia being the common sites for tumor, massive skeletal defects are commonly encountered following wide surgical excision of the lesion. Large defects can also be seen in cases of Failed Total Knee Arthroplasty, infection and complex trauma. Because of the limited longevity of megaprosthesis and the need of future revision, their use has been limited to the elderly only. Biological reconstruction in young patients using osteoarticular allografts have been associated with high rate of failures due to fractures.¹⁰⁶ Because of the encouraging results with the use of APCs in the reconstruction of proximal femur and proximal humerus, indications have been extended for their use in distal and proximal tibia as well. The outcomes of use of APCs around the distal femur and proximal tibia, reported in different studies are summarized in Table 9, Table 10 respectively.

Table 9.

Summary of the data from the recent studies on the use of Allograft Prosthesis Composite for the management of massive skeletal defects in distal femur.

Authors	Diagnosis	No of patients	Mean age (years)	Average Follow up	Clinical outcome	Radiological Outcome	Complications	Result	Survival
Moon et al.107	Tumors	12	19	89 m	MSTS score available for 6 patients;	–	8 patients had complications non-union, fracture, infection and stem perforation	3 non- union and 2 failures revised	–
					Average = 90%
Mo S et al.108	Tumors	12	29.5	45.7 m	MSTS in 9 patients with preserved limb = 27	–	1 fracture	1 died
							1 infection	4 revisions
							1 instability
							1 local recurrence
Saidi K et al.109	Fractures	7 APC	79		KSS =  74.1	–	1 infection	3 revisions
		9 RSA					1 dislocation
		7 DFR					1 non-union
Ye ZM et al.110	Tumors	12 PF	–	64 m	EFS = 23.4	No loosening	No dislocation	3 died	–
		10 DF
		3 PT
Farfalli et al.111	Tumors	(Group 1) 50 APC (28 DF, 22 PT) with non-constrained prosthesi	35 in both	Group 1–69 m	MSTS = 25 in Group 1	–	Group 1:	Group 1:	Group 1: 69% at 5 years and 62% at 10 years
				Group 2–75 m	MSTS = 25.3 in Group 2		8 infection	2 died,
		(Group 2) 36 APC (17 DF, 19 PT) with constrained prosthesis					3 fracture	16 APC removed	Group 2: 80 % at 5 years and 53 % at 10 years
							2 instability
							1 loosening	Group 2:
							1 local recurrence	5 died,
							1 non-union	9 APC removed
							Group 2:
							3 infection
							3 fracture
							3 loosening
Wilkins RM et al .112	Revision of distal femoral replacement in tumors	4	17	59 m	MSTS = 62%	–	No fracture	No revision
							No loosening
							No infection

Abbreviations: m = months, y = years, APC = Allograft Prosthesis Composite, DF = Distal Femur, PT = Proximal Tibia, RSA = revision systems, DFR = Distal Femur Endoprostheis, KSS = Knee Society Score, MSTS = Musculoskeletal Tumor Society Score.

Table 10.

Summary of the data from the recent studies on the use of Allograft Prosthesis Composite for the management of massive skeletal defects in proximal tibia.

Authors	Diagnosis	No of patients	Mean age (years)	Average Follow up	Clinical outcome	Radiological Outcome	Complications	Result	Survival
Campanacci et al.113	–	19	6–16  y	78 m	13 patients who retained original implant has MSTS of 22 points (range, 12 to 30 points).	–	6 fracture	5 revised	68 months (6 to 188),
							2 non-union	1 died	72.2% at 5 year,
							1 infection		56.1% at 10 year
							1.9 cm of LLD
Donati D et al.114	58 tumor	62	24 y	72 m	90% of patients had MSTS higher than 65	2 loosening	15 infection	–	73.4% at 5 y
	4 reconstruction of failed procedure						3 local recurrences
Capanna R et al .115	Tumors	14	34.9 y	4.5 y	MSTS = 83%	–	2 infection	4 died	–
							2 prosthesis failure
							1 stem fracture
Biau D et al.116	Tumors	26 APC in PT	25 y	62 m	–	–	6 infection	38 re-operations (15 revisions) in 18 patients	72 % at 5 y
							9 mechanical failures		43 % at 10 y
Biau DJ et al.117	Tumors	26	24 y	128 m	–	6 showed signs of partial resorption	7 fracture	10 died	68 % at 5 y
							6 infection	14 revised	33 % at 10 y
Gilbert et al.118	Tumors	12	34.5 y	49 m	MSTS = 24.3 (81%)	–	1 deep infection	3 died	79% at 5 y
								No revision
							1 flap failure	1 re-operation for infection
Jeon DG et al.119	Tumors	13	26 y	43 m	MSTS = 23.6	1 loosening	3 infection	4 removal of prosthesis	76.9 % at 5y
							4 non-union

Abbreviations: m = months, y = years, LLD = limb length discrepancy, MSTS = Musculoskeletal Tumor Society Score, APC = Allograft Prosthesis Composite, PT = Proximal Tibia.

The various studies (mentioned in the table) have shown good to excellent results following knee reconstruction with the use of APCs in distal femur and proximal tibia. The survivorship has been reported as low as 33% at 10 years for proximal tibia to as high as 80% at 5 years for distal femur. The senior author (RM) has reported the successful outcome of using a dual massive allograft (distal femoral and proximal tibial) for the reconstruction of large femoral and tibial uncontained defects in the setting of revision knee arthroplasty.¹²⁰ The patient, currently at 11 years follow is doing well without any sign of infection, graft failure or loosening of the implant.

3.2.3. Literature review comparing megaprosthesis with allograft prosthesis composite

There are very few studies comparing the outcome of megaprosthesis and allograft prosthesis composite for major reconstruction of massive bone defects. In addition, majority of them are retrospective analyses. The results are different for different etiologies and so are the survivorships. Table 11 summarizes the results of different studies comparing the outcome following use of megaprosthesis and allograft prosthesis composite for the reconstruction of massive skeletal defects in different anatomic sites.

Table 11.

Summary of the results of different studies comparing the outcome following use of megaprosthesis and allograft prosthesis composite for the reconstruction of massive skeletal defects in different anatomic sites.

Authors & Anatomic site	Megaprosthesis					APC
	No. of patients	Mean Follow-up	Outcome	Results	Survival	No. of patients	Mean Follow-up	Outcome	Results	Survival
Michiel et al.121	14	10 y	21% complications	1 revision	88% at 5 years	10	10 y	40% complications	3 revisions	60% at 5 years
Proximal Humerus
Benedetti et al.122	10	118 m	MMT = 4/5 (hip abductors)		–	10	60 m	MMT = 4/5 (hip abductors)	–	–
Proximal Femur			MSTS = 87%					MSTS = 90%
			Gait: Lower cadence					Gait: Higher cadence
Anract et al.123	20	–	Higher incidence of limp and use of crutches	–	73 + 11 % at 5 years and 0% at 10 years	21		Lower incidence of limp and use of crutches	Allograft resorption seen in 50% cases without affecting the function	77 + 12% at 5 and 10 years
Proximal Femur
Farid et al.124	52	146 m	2 infections	–	86% at 10 years	20	76 m	1 infection	–	86% at 10 years
Proximal Femur			10% aseptic loosening					10% non-union
			MSTS = 70%					MSTS = 82%
			HAS = 2.8/5					HAS = 4.6/5
Zehr et al.125	17 (18 MPs)		MSTS = 80%	8revisions	58% at 10 years	16(18APCs)		MSTS = 87%	1 revised to rotationplasty	76% at 10 years
Proximal Femur			47% complications					18% complications	1 hip disarticulation
									2 deaths from disease
			2 stem breakage					1 persistent nonunion
			1 loosening
			1 infection
			1 recurrence
			3 instability
Zimel et al.126	47	7 y	11% recurrence	9 deaths from disease	87% at 10 years	38 (Condyle sparing allograft)	7 y	18% recurrence	8 deaths from disease	81% at 10 years
Distal Femur				53% alive with no disease					68% alive with no disease
				17% alive with disease					11 % alive with disease
Muller et al.127	23	62 m	ISLOS Score:	5 failures:	78.8% at 10 years	19	62 m	ISLOS Score:	4 failures:	93.7% at 10 years
Proximal Tibia			6 Excellent	1 amputation				10 Excellent	1 amputation
			11 Good	4 implant removal				11 Good	2 implant removal
			1 Fair					1 Fair	1 change of inlay
Wunder et al.128	64 (50 DF, 14 PT)	Minimum 3 years	MSTS = 26.3	2 infection	91% at 3 years	11 (6 DF, 5 PT)		4 infection	MSTS = 20	22% at 3 years
Knee				4 prosthesis breakage				5 allograft fracture
								1 loosening

Abbreviations: y = years, m = months, MMT = Manual Muscle Test, MSTS = Musculoskeletal Tumor Society Score, HAS = Hip Abductor Strength, MP = Megaprosthesis, ISLOS = International Society of Limb Salvage, DF = Distal Femur, PT = Proximal Tibia.

4. Conclusion

Megaprosthesis and Allograft Prosthesis Composite (APC) both present viable options for the management of massive skeletal defects. The development in megaprosthesis include improved material and designs, silver coating to prevent infection and technologies to improve osteointegration in the host bone. The APC on the other hand is continuously finding applications for a wide array of newer indications. The complication rates remain high with both technologies and the most notable ones are infections and complications due to the failure to restore soft tissue envelope. The choice is decided by the age of the patient, level of activity, affordability, availability of bone allografts, and, skill of the surgeon. Still, APC remains the method of choice for reconstruction for the young patient where further surgeries may be required.

Funding

No funds were received in the form of payment or services from a third party for any aspect of the submitted work.

Conflict of interest

None.