Metaphyseal Metal Sleeves for Reconstruction of Severe Knee Bone Defects: Excellent Survival Rate at a Mean Follow‐Up of 6.4 Years

Abstract

Objective

Management of bone loss in complex primary and revision total knee arthroplasty is key to the surgeries. Metaphyseal metal sleeves have been increasingly used recently to reconstruct severe knee metaphyseal bone defects. This study aimed to investigate the outcomes of the metaphyseal sleeve reconstructing Anderson Orthopedic Research Institute (AORI) type II and type III bone defects of knee joint.

Methods

From 2014 to 2019, a total of 44 knees were enrolled in this clinical retrospective study after the screening, including seven cases of primary TKA and 37 cases of revision TKA. The types of bone defects involved in this study were AORI types II and III, and did not involve AORI type I bone defects. Patients' knee function preoperatively and postoperatively as well as quality of life were recorded and analyzed. Analysis included the American Knee Society Score (KSS), hospital for special surgery knee score (HSS), the Western Ontario and McMaster Universities (WOMAC) index, the Short Form 12 (SF‐12) health survey, visual analogue scale score, and radiographic assessment with a mean follow‐up of 6.4 years. Paired t‐tests were used to determine the significance of changes in clinical scores and knee mobility.

Results

A mean follow‐up of 77.2 (±17.6, standard deviation [SD]) months was performed, and none of the patients underwent knee revision for infection or aseptic loosening. At the last follow‐up, the KSS knee score changed statistically from 37.1 (±19.7) preoperatively to 86.5 (±13.6, SD, p < 0.001) postoperatively and the KSS function score from 32.7 (±24.0) preoperatively to 78.3 (±15.6, SD, p < 0.001) postoperatively. The knee mobility improved from a mean of preoperative 72.61° (±33.42°, SD) to 108.52° (±24.15°, SD, p < 0.001). Postoperative radiographs showed that the host bone was tightly integrated with the metaphyseal metal sleeve, and there was no obvious translucent line formation around the sleeve. Of the patients, 86.4% had a postoperative satisfaction score ≥8 (10‐point scale).

Conclusion

At the mean follow‐up of 6.4 years, the survival rate of the metaphyseal sleeves was 100%. Metaphyseal sleeves combined with cementless stems is an excellent and viable option for reconstruction of AORI type II and type III bone defects of the knee.

In our study the most important finding was that the metaphyseal sleeve showed a 100% survival rate with a mean follow‐up period of 6.4 years and a maximum follow‐up period of 8.8 years.

Introduction

Stable fixation of implants affects the outcome of complex primary and revision total knee arthroplasty (TKA) procedures. During complex primary TKA as well as revision TKA (rTKA), bone defects are often present to varying degrees, and how to reconstruct the bone defect and restore bone volume is the key to the procedure. The Anderson Orthopedic Research Institute (AORI) classification is now commonly used as a guide for reconstructing bone defects in TKA revision surgery. ¹ AORI type I defects can usually be reconstructed using a standard revision prosthesis, while for more severe type II or III defects, various forms of metaphyseal fixation, augmentation, or bone grafting are required for management.

In recent years, more attention has been paid to the fixation of the metaphyseal region. ² , ³ , ⁴ The metaphyseal metal sleeve is a new option for reconstructing bone defects in the knee, with good survival rates reported in several publications. ⁵ , ⁶ The newly metaphyseal metal sleeve, which can effectively reconstruct the metaphyseal defect, becomes integral with the articular prosthesis and extension stem through a unique locking mechanism to achieve a firm fixation of the metaphysis region to the diaphysis region. The porous surface of the sleeve allows for good bone ingrowth after implantation into the tibia or femur, and its external stepped structure and oval cross‐section allow for good stability in both the axial and longitudinal directions.

The metaphyseal metal sleeve with a cementless stem can effectively reconstruct severe bone defects in the knee ⁷ , ⁸ , ⁹ , ¹⁰ , ¹¹ and can serve as a stable fixation platform to provide reliable structural and mechanical support for the implant. ¹² , ¹³ Short‐ to medium‐term clinical outcomes of metaphyseal sleeves are satisfactory, but medium‐ to long‐term clinical outcomes are lacking. In addition, screws and bone cement are commonly used in complex primary TKA, while the metaphyseal sleeve is rarely used. The aims of this study were to: (i) investigate the mid‐ and long‐term survival rates as well as clinical outcomes of the metaphyseal sleeve; and (ii) investigate the use of the metaphyseal sleeves in complex primary TKA as well as rTKA. The mean follow‐up in this study was 6.4 years while the longest follow‐up was 8.8 years.

Patients and Methods

Patients

This study was initiated through the Ethics Committee of General Hospital of Chinese People's Liberation Army approval (S2022‐425‐01). Patients who underwent TKA or rTKA using a metaphyseal sleeve at our institution from 2014 to 2019 were collected retrospectively. The inclusion criteria were: (i) adult patients operated on by the same surgeon; (ii) patients with AORI type II and type III bone defects of the knee treated with metaphyseal sleeves; and (iii) patients were followed for at least 4 years and had complete clinical data. Patients with incomplete clinical data were not included in this study.

A total of 43 patients (44 knees) were enrolled after the screening, including seven cases of primary TKA and 37 cases of revision TKA. This series of patients was followed up for a mean duration of 77.2 months (Table 1).

TABLE 1.

Preoperative demographics

Demographics	Mean (range)
Gender	33 females/11 males
Age (years)	65.9 (38–85)
Body weight (kg)	71.1 (55–108)
Height (cm)	161.6 (150–178)
BMI (kg/m2)	27.2 (21.3–40.2)
Inverted knee/ectropion knee	8/2
Average follow‐up time (months)	77.2 (48–105)

Primary TKA etiology includes severe bone defects with knee instability and flexion contracture due to osteoarthritis (OA) and rheumatoid arthritis (RA). The most common causes of revision TKA included infection (35.1%), loosening (18.9%), instability (18.9%), and postoperative pain with activity limitation (13.5%) (Table 2).

TABLE 2.

Causes for revision TKA

Reason	Number	Percentage
Loosening	7	18.9%
Infection	13	35.1%
Pain/stiffness	3	8.1%
Instability	7	18.9%
Peri‐prosthetic fractures	1	2.7%
Mechanical failure	1	2.7%
Postoperative pain with limitation of movement	5	13.5%

Surgical Technique

All procedures are performed by the one experienced surgeon. A medial parapatellar approach was taken to reveal the interior of the joint. Careful removal of the original prosthesis and adequate cleaning of residual bone cement and fibrous tissue were required in rTKA. Sleeve implantation was carried out using a ream and broach technique to prepare the tibial metaphysis first. The bone preparation of the distal femur was performed in the same manner. After ensuring that the flexion–extension gap was balanced, the assembly and implantation of the sleeves and extension stems and prosthetic components were performed. All sleeves in this study were treated with cementless extension stems. Table 3 summarizes the sleeve size and matched stem length information used for this group of patients.

TABLE 3.

Size of the sleeve (mediolateral dimension) and the length of the stem

Size (mm)	No. of cases	Percentage
Sleeve
29	3	5.3%
31	6	10.5%
34	3	5.3%
37	13	22.8%
40	4	7.0%
45	21	36.8%
53	7	12.3%
Stem
75	54	94.7%
115	3	5.3%

A total of 57 metaphyseal metal sleeves were used in this study. The tibial and femoral bone defects were classified according to the AORI classification criteria and intraoperative findings. In this series, 18 cases (31.6%) presented as type IIA, 30 cases (52.6%) presented as type IIB, and 9 cases (15.8%) presented as type III (Table 4).

TABLE 4.

Bone loss against AORI classification

AROI grade	Tibia	Femur	Both the tibia and femur
IIA	15	3	18 (31.6%)
IIB	21	9	30 (52.6%)
III	6	3	9 (15.8%)

Abbreviation: AORI, Anderson Orthopedic Research Institute.

Clinical and Radiographic Assessment

The incidence of intraoperative and postoperative complications in patients was recorded. Anterior–posterior and lateral radiographs of the knee were taken at 3, 6, 12, 24, 36 months and the last follow‐up after surgery. Hospital for special surgery knee score (HSS), the American Knee Society Score (KSS), the Western Ontario and McMaster Universities (WOMAC) index, the short form 12 (SF‐12) health survey and visual analogue scale (VAS) were used to evaluate patients' preoperative and postoperative knee function as well as the quality of life. A 10‐point scale was used to evaluate the subjective satisfaction of patients, with higher scores resulting in higher satisfaction.

Statistical Analysis

The results of this study were analyzed using SPSS software version 26.0 (SPSS Inc., Chicago, IL, USA). For all variables, descriptive statistics were performed with mean, median, range, and standard deviation. Paired t‐tests were used to determine the significance of changes in clinical scores (HSS, KSS, WOMAC, SF12) and knee mobility.

Results

Clinical and Radiographic Outcomes

With a mean follow‐up of 77.2 (±17.6, standard deviation [SD]) months and a sleeve survival rate of 100%, none of the patients underwent revision surgery. Revision was defined as a new operation in a previously resurfaced knee in which one or more of the components were exchanged, removed, or added. The average operative time was 2.1 (range, 1.3 to 2.9) hours and the average operative bleeding was 600 (range, 400 to 1000) ml. A comparison of the patient’ preoperative and last follow‐up results are summarized in Table 5. The clinical scores of all patients showed an increasing trend from year to year during the follow‐up. At the last follow‐up, the patient's HSS score went from preoperative 48.20 (±13.74, SD) to 83.59 (±7.88, SD, p < 0.001). The Womac results showed a great improvement at the last follow‐up, which were statistically different. Almost all patients mentioned a great improvement in their quality of life after surgery, which is reflected by the SF‐12 scale. The KSS knee score changed statistically from 37.1 (±19.7, SD) preoperatively to 86.5 (±13.6, SD, p < 0.001) postoperatively and the KSS function score from 32.7 (±24.0) preoperatively to 78.3 (±15.6, SD, p < 0.001) postoperatively, the VAS score changed from 5.9 (±2.0, SD) preoperatively to 1.2 (±1.1, SD, p < 0.001) postoperatively, and knee mobility improved from a mean of preoperative 72.61° (±33.42, SD) to 108.52° (±24.15, SD, p < 0.001).

TABLE 5.

Preoperative and last follow‐up scores

	Preoperative	1 year		3 year		Last follow‐up
		Mean (±SD)	p value	Mean (±SD)	p Value	Mean (±SD)	p value
HSS	48.2 (±13.7)	75.5 (±6.2)	<0.001	79.8 (±6.8)	<0.001	83.6 (±7.9)	<0.001
KSS knee	37.1 (±19.7)	75. 6 (±10.7)	<0.001	80.2 (±12.1)	<0.001	86.5 (±13.6)	<0.001
KSS function	32.7 (±24.0)	69.4 (±10.8)	<0.001	75.3 (±12.6)	<0.001	78.3 (±15.6)	<0.001
WOMAC Pain	20.7 (±7.3)	8.4 (±3.6)	<0.001	6.3 (±3.2)	<0.001	5.3 (±3.8)	<0.001
WOMAC Stiffness	9.1 (±4.2)	3.3 (±2.5)	<0.001	2.4 (±2.4)	<0.001	1.6 (±2.5)	<0.001
WOMAC Function	62.4 (±21.6)	26.1 (±15.6)	<0.001	21.4 (±17.3)	<0.001	19.50 (±17.9)	<0.001
SF‐12PCS	29.0 (±3.3)	45.4 (±7.6)	<0.001	47.5 (±7.3)	<0.001	51.1 (±8.2)	<0.001
SF‐12MCS	27.9 (±5.3)	44.9 (±7.8)	<0.001	46.9 (±8.5)	<0.001	49.4 (±8.0)	<0.001
VAS	5.9 (±2.0)	2.0 (±0.9)	<0.001	1.6 (±0.9)	<0.001	1.2 (±1.1)	<0.001
ROM	72.6° (±33.4°)	102.5° (±19.7°)	<0.001	104.9° (±21.0°)	<0.001	108.5° (±24.2°)	<0.001

The patient's preoperative and postoperative X‐rays at different times (1 day, 3 months, 1 year, 3 years, 5 years, and final follow‐up after surgery) showed that all sleeves were in tight contact with the host bone and successfully repaired the metaphyseal bone defect (Fig. 1). There was no significant translucent line formation around the metaphyseal metal sleeve. All patients had good alignment of the knee joint.

FIG. 1.

(A) A 65‐year‐old woman (BMI: 29.3 kg/m²) with severe osteoarthritis of the right knee on preoperative radiographs (A). Knee radiographs were taken at 1 day postoperatively (B), 1 year postoperatively (C), 3 years postoperatively (D), and 5 years postoperatively (E) after this patient underwent TKA of the right knee. (B) A 70‐year‐old woman (BMI: 31.6 kg/m²) underwent a second‐stage revision for a deep periprosthetic infection. These are preoperative (F) and postoperative (G), 3‐month postoperative (H), 1‐year postoperative (I), and 5‐year postoperative (J) radiographs using the tibial metaphyseal sleeve.

Complications

The intraoperative fracture was the main intraoperative complication. Four patients had minor longitudinal fractures during the preparation of the sleeve admitting cavity. For the above patients, intraoperative testing of the prosthesis stability was OK and no special treatment was given. Postoperative follow‐up showed good fracture healing, no significant loosening of the prosthesis, and good knee flexion function. Two cases with wound oozing and delayed healing were healed by postoperative tight sutures and pressure dressing. One patient had a postoperative Superficial wound infection, which was treated with debridement and antibiotics, and cured. One patient presented pain in the distal tibia.

Patient Satisfaction

Of the patients 86.4% had a postoperative satisfaction score ≥8. There were three patients with satisfaction scores less than 6. Two of them had preoperative knee stiffness and postoperative problems such as poor knee mobility and pain, and one expressed dissatisfaction with recurrent wound oozing after surgery (Fig. 2).

FIG. 2.

Patient satisfaction rating after surgery (1–10 score).

Discussion

Excellent Survival Rate and Clinical Outcomes

The most significant finding of this study was the metaphyseal sleeves showed a 100% survivorship with an average follow‐up period of 6.4 years. None of the patients underwent knee revision for infection or aseptic loosening during the follow‐up period, with a maximum follow‐up of 8.8 years. Previously, metaphyseal sleeves were often used in rTKA and rarely in primary TKA, but in this study, the use of metaphyseal sleeves to treat complex primary TKA was associated with equally excellent clinical outcomes as rTKA. ¹⁴ This finding demonstrates the potential of metaphyseal sleeves to be used in primary TKA.

The clinical results and radiographic findings at this follow‐up were encouraging. Clinical scores showed statistically significant improvements at the last follow‐up, and the mean postoperative knee mobility improved by approximately 36° compared to the preoperative period. Radiographic findings demonstrate the potential for bone ingrowth and long‐term biologic fixation of the metaphyseal metal sleeve. Intraoperative fractures, which were the main complication in this study, occurred in the revision TKA. We analyzed the occurrence of intraoperative fractures due to severe sclerosis of the proximal tibial cortex and loss of cancellous bone, which often occurs after infection and implantation of a prosthetic placeholder.

Comparison with Other Methods of Reconstructing Bone Defects

Reconstructing severe bone defects, achieving soft tissue balance, and restoring normal knee motion during rTKA are serious challenges that surgeons need to face. Previously, allogeneic structural bone grafting was widely used to reconstruct severe bone defects in the knee joint. Structural bone grafting can accommodate a variety of different sizes and shapes of defects, but it also has significant disadvantages, including long surgical time, the difficulty of operation, problems of bone graft resorption and non‐healing, the possibility of spreading disease, high price, and shortage of supply. ¹⁵ The re‐revision rate of allogeneic structural bone grafting within 5 years is reported in some of the literature to be close to 20%. ¹⁵ The high failure rate reported has led to a decline in the use of structural bone grafting, which in recent years has been replaced by cones and sleeves for the reconstruction of the metaphysis. ² , ⁸ , ¹⁶

Both cones and sleeves can be used to treat severe bone defects in the knee metaphysis, and there is no clear advantage of one method over the other in terms of survival as well as clinical outcomes. ¹⁷ , ¹⁸ , ¹⁹ In a meta‐analysis, Fischer et al. noted a higher rate of periprosthetic joint infection after rTKA using the cones compared to the sleeves, despite similar survival rates for both. ¹⁷ Small et al. retrospectively compared 225 patients with cones and 242 patients with sleeves, and they suggested that there was no significant difference between the two implants and that surgeons should be comfortable using either implant with confidence to manage severe bone loss in rTKA. ²⁰

Sleeves Combined with Cementless Stems Provide Reliable Initial Stability

Morgan‐Jones et al. ³ proposed the concept of three‐zone fixation to assist in preoperative planning and to help obtain reliable fixation, and the authors concluded that fixation of at least two of the three zones (epiphysis, metaphysis, and diaphysis) is necessary to obtain stable fixation. The metaphyseal metal sleeve with an extension stem provides excellent fixation of both the metaphysis and the diaphysis and serves as a stable platform to provide reliable structural and mechanical support for the implant. In recent years, the metaphyseal metal sleeve has been widely used, and several literature reports satisfactory early to mid‐term clinical outcomes. Martin‐Hernandez et al. ²¹ followed 134 patients for a median time of 71.5 months with an aseptic survival rate of 100%. Bloch et al. ⁹ followed up 319 cases of revision TKA for a mean of 7.5 years and found survival rates of 99.1% at 3 years, 98.7% at 5 years, and 97.8% at 10 years.

The metaphyseal metal sleeve has a porous coating on its surface, which makes it have a high void ratio and high friction coefficient and can increase the tendency of bone growth into the bone to achieve biological fixation. The sleeve can be used with an extension stem for fixation in the diaphyseal region. The sleeve can be paired with an extension stem, which helps to achieve good prosthetic alignment. The extension stem transfers stress from the bone‐prosthesis interface to the distal cortical bone, which can result in better protection of the metaphysis, increase the mechanical stability of the knee joint, and reduce the risk of aseptic loosening. ²² , ²³ , ²⁴ , ²⁵

Controversy over the Need for an Extension Stem

There is debate as to whether the metaphyseal metal sleeve should be used with an extension stem, and some believe that in some cases, the sleeve alone is a viable way to reconstruct a knee bone defect. Fonseca et al. ²⁶ performed a finite element analysis of the stresses and micro‐motion differences between a sleeve with and without a stem, and the authors suggested that a stem is not necessary for the initial sleeve‐bone stability and that a separate sleeve can be considered for bone defect reconstruction in cases where a stem cannot be used. Scior et al. ²⁷ proposed the use of stemless sleeves for AORI type I and contained AORI II bone defects as a promising option with a 5‐year stemless sleeve survival rate of 99%, however, for AORI type II open bone defects and type III bone defects, the epiphysis is often faced with severe bone defects that do not provide adequate fixation in this area, so fixation of the diaphysis is necessary.

Stemless sleeve reconstruction of bone defects is prone to poor prosthesis alignment, knee pain, and long‐term results in aseptic loosening of the prosthesis. Agarwal et al. ²⁸ reported two cases of early loosening in which failure to use a stem was the cause of loosening, and the authors recommended routine use of a stem in all patients, which would also help achieve good prosthesis alignment. Gøttsche et al. ²⁹ used a stemless sleeve to treat severe bone defects in the knee to reduce stem‐end pain. In their study, two (2.8%) of 71 patients with rTKA had aseptic loosening, seven (11%) had periprosthetic translucent lines, and most patients (56%) reported periprosthetic pain, with only 31.49% of patients feeling satisfied. Whether “end‐of‐stem pain” has been eliminated or replaced by “end‐of‐sleeve pain” is still uncertain. The authors suggest that periprosthetic pain may be related to the non‐optimal alignment of the prosthesis, and they recommend the use of a stem to improve the alignment of prosthesis as well as to reduce pain.

All sleeves in this study were paired with cementless stems and no one developed aseptic loosening during the follow‐up time, with only one patient experiencing pain at the tip of the stem. We believe that the sleeve with extension stem is beneficial in reducing the stress at the implant‐bone interface to increase the initial stability of the implant and in assisting the alignment of the prosthesis, both of which are beneficial to the long‐term fixation of the implant.

Limitations of the Study

This study has several limitations. This study had a long time span with a maximum follow‐up of 105 months and a minimum follow‐up of 48 months. However, the first three years as well as the last follow‐up data were complete in this study, so we thought we could put them together for discussion. In addition, the study did not design a control group and failed to compare the procedure using sleeve with other contemporaneous TKA or rTKA. However, we believe that the 100% prosthesis survival rate is sufficient to demonstrate the excellence of the metaphyseal metal sleeve in the reconstruction of severe metaphyseal defects of the knee.

Conclusion

In this retrospective study, the sleeve survival rate was 100% with a maximum follow‐up of 8.8 years, and none of the patients underwent knee revision due to infection or aseptic loosening. Postoperative radiographs showed that the host bone was tightly integrated with the metaphyseal metal sleeve, and there was no obvious translucent line formation around the sleeve. Metaphyseal metal sleeves paired with cementless stems are an excellent and viable option for reconstruction of AORI type II and III bone defects of the knee. Metaphyseal sleeve is an excellent choice for patients who need primary TKA due to severe bone loss or severe internal or external deformity caused by OA or RA. For patients requiring knee revision due to infection, aseptic loosening, or other reasons, the metaphyseal metal sleeves can effectively restore the lost bone volume and achieve stable fixation of the prosthesis. Larger samples and longer‐term follow‐up results are still warranted.

Ethics Statement

This study was performed in line with the principles of the Declaration of Helsinki. Approval was granted by the Ethics Committee of Medical School of Chinese PLA.

Author Contributions

Yonggang Zhou and Haiyang Ma contributed to the study conception and design. Material preparation, data collection performed by Yang Liu and Yanchao Zhang. Junmin Shen and Bohan Zhang performed analysis. The first draft of the manuscript was written by Yang Liu and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.