Outcomes following open acetabular labrum reconstruction: Comparing fresh-frozen tendon with fresh meniscus allograft transplantation

Abstract

Background

Symptomatic acetabular labral insufficiency in young, active patients is often treated with labral repair or reconstruction using fresh-frozen allografts. However, fresh-frozen tendon allografts do not have tissue or material properties that closely mimic acetabular labral fibrocartilage. Recent studies suggest meniscal allografts may be a better biomechanical, geometric, and material alternative for acetabular labrum reconstruction (ALR).

Hypothesis

Patients undergoing open ALR using fresh meniscus allograft transplants (MAT) will have better outcomes than those using fresh-frozen tendon allografts transplants (TAT) when comparing initial treatment success, diagnostic imaging assessments, and patient-reported pain and function scores.

Study design

Cohort Study.

Methods

With IRB approval, patients undergoing ALR with either TAT or MAT were included when initial (>1-year) outcomes data related to treatment success, pain, and function were available. In addition, a subcohort of patients underwent magnetic resonance imaging at least 6-months after surgery to evaluate allograft healing.

Results

Initial success rate, defined as no need for ALR revision or conversion to total hip arthroplasty (THA), was 88.9% for the entire group (n = 27, TAT = 5, MAT = 22) with 1 (20%) patient in the TAT cohort and 2 patients (9.9%) in the MAT cohort undergoing THA. In the MAT cohort, significant improvements were documented for physical function and pain scores at 1 year and final follow-up (FFU)(mean 26.8 months). Improvements in pain and function were noted at 1-year, but not at FFU (mean 59.6 months) in the TAT group. MRIs completed at least 6 months after labrum reconstruction showed improved allograft integrity and integration in the MAT cohort over the TAT cohort.

Conclusion

For acetabular labrum reconstructions, MAT was associated with a higher initial success rate, superior patient reported outcomes, and subjectively better MRI findings when compared to TAT.

1. Introduction

Symptomatic acetabular labral pathology is diagnosed more often in recent years, particularly in young, active individuals as a consequence of traumatic or repetitive injuries, femoral acetabular impingement (FAI), or developmental dysplasia of the hip (DDH).1, 2, 3, 4 Insufficiency of the labrum results in altered joint physiology and biomechanics, which can cause hip pain and dysfunction. It is hypothesized that untreated labral pathology frequently leads to early onset hip osteoarthritis (OA)5, 6, 7, 8, 9, 10 and the potential need for total hip arthroplasty at a relatively young age.^2,3,11 Therefore, effective methods for preserving or restoring labral structure and function are critical for re-establishing joint health and mitigating the development of hip OA.12, 13, 14, 15, 16 Surgical restoration of labrum structure and function can be accomplished by repair or reconstruction. Acetabular labral repair using open or arthroscopic techniques is preferred when sufficient functional tissue remains, and is not ossified or degenerative.12, 13, 14, 15, 16 Labral reconstruction is considered when symptomatic labral pathology is irreparable and for labrum revision surgeries.^2,17, 18, 19 In addition, reconstruction may be preferred for older patients and those with non-functional tissue, dense capsulolabral adhesions, and/or Tonnis grade 1–2 hip OA.^17,18,20, 21, 22, 23, 24, 25, 26 Labral reconstruction is performed using autografts (e.g., ligamentum teres, joint capsule, rectus femoris, fascia lata, iliotibial band, gracilis tendon, quadriceps tendon) or allografts (e.g., anterior and posterior tibialis, semitendinosus, and peroneus brevis tendons, fascia lata) through either an open or arthroscopic approach.^{2,17,25,27,28}

In the United States, allografts are used more commonly than autografts for acetabular labrum reconstruction because of size and geometry benefits, lack of donor site morbidity, and reduced surgery and anesthesia duration.^17,20, 21, 22^,24,29,30 Among these, fresh-frozen tendon allografts are most frequently used and have been reported to consistently result in good to excellent initial outcomes.^18,31, 32, 33 However, reconstructions using tendon allograft do not consistently restore the size, geometry, properties, or functions of native labrum, and reported to fail in up to 24% of cases in some studies.^18,24,31, 32, 33, 34, 35 As such, some have advocated for the use of meniscus allografts for labral reconstruction because they are more similar to acetabular labrum in tissue composition, morphology, and architecture; synthetic and metabolic profiles; and material properties compared to tendon allografts.^10,36, 37, 38 An open surgical labral reconstruction technique using fresh-frozen, non-irradiated medial meniscus allografts has been described and results for seven cases (mean follow up of 17.4 months).³⁶ No significant adverse outcomes were noted and patients reported significant improvements in hip pain, function, and flexion.³⁶ Based on results comparing fresh (viable) meniscus allografts to fresh-frozen meniscus allografts for meniscus allograft transplantation (MAT) in the knee,^39,40 as well as preclinical studies verifying safety and efficacy of fresh MAT for acetabular labrum reconstruction in a large animal model,^39,41, 42, 43 we applied an evidence-based shift in practice to use of fresh MAT for acetabular labral reconstruction (ALR) at our institution. This study was designed to analyze and report indications, transplantation technique, and outcomes for patients undergoing open ALR using fresh MAT versus fresh-frozen tendon allografts. The hypothesis to be tested was that patients undergoing open ALR using fresh MAT will have better outcomes than those using TAT when comparing initial treatment success, diagnostic imaging assessments, and patient-reported pain and function scores.

2. Methods

2.1. Study patients

With institutional review board approval (#2014820), patients were prospectively enrolled into registry to track outcomes after hip allograft transplant surgeries. All grafts used for labral reconstruction were acquired from American Association of Tissue Banks (AATB) and in conformance to the US Food and Drug Administration Public Health Services Act section 361 classification of a human cell and tissue product. Standard preservation (SP) tendon allografts were fresh-frozen and were obtained from 1 of 3 tissue banks. After Missouri Osteochondral Preservation System (MOPS®, MTF Biologics) fresh meniscus allografts became commercially available, we shifted to exclusive use of MOPS-preserved meniscus allografts obtained from one AATB-accredited source.39, 40, 41, 42, 43, 44 Patients included in the study underwent open acetabular labral reconstruction as indicated for symptomatic hip pathology including documented irreparable acetabular labral insufficiency consecutively between November 2015 and June of 2021. After discussion of nonsurgical and surgical options, patients opted for allograft labral reconstruction and were approved for health insurance coverage. Prior to surgical consent and registry enrollment, each patient was thoroughly counseled by the attending surgeon and joint preservation healthcare team to discuss risks, benefits, expectations, and limitations and to outline postoperative rehabilitation and documented treatment outcomes associated with the planned procedure to allow for shared decision-making regarding treatment options.⁴⁵

2.2. Surgical procedures/comparison cohorts

All surgeries were performed by the senior author (BDC) via surgical hip dislocation (SHD).⁴⁶ A step-cut greater trochanteric osteotomy was performed.⁴⁷ When concurrent proximal femoral rotational osteotomy (PFRO) was performed to address abnormal femoral torsion, the greater trochanteric and proximal femoral osteotomies were combined. When indicated, femoral head and neck osteoplasty was performed using an osteotome and high-speed burr prior to labral reconstruction. When concurrent femoral head osteochondral allograft (OCA) transplants were performed, cylindrical “plug” grafts or custom-cut shell grafts were used based on defect size and configuration (see Supplement).⁴⁸ For acetabular labrum reconstruction, irreparable labral tissue was resected, the defect size was measured, and the recipient bed was prepared by decortication to bleeding bone using a high-speed burr (Fig. 1A–C). Cohort assignment was based on graft availability in conjunction with the evidence-based transition in graft type.39, 40, 41, 42 For the objective of the present study, cohort assignment was based on allograft type, as follows:

• •Meniscus allograft transplant (MAT) – Fresh MOPS-preserved meniscus allograft was prepared by sharp dissection from the tibial plateau followed by trimming to match the length of the defect as well as the width and height of native/remaining labrum. Choice of medial versus lateral meniscus allograft was made based on subjective assessment of best-fit with respect to size, geometry, and curvature. Passing sutures were placed along the peripheral margin of the meniscus allograft at one-cm intervals such that each entered and exited at the inferior and superior margins, engaging meniscal circumferential fibers. Knotless labral-based suture anchors and a posterior junctional suture anchor were placed at one-cm intervals from anterior to posterior along the recipient bed while the graft was being prepared. The hip was reduced, and all anchor sutures were passed into the meniscus allograft using the pre-placed passing sutures. Allograft fixation was performed via sequential tightening of anchor sutures from anterior to posterior until initially seated in the acetabular recipient bed. The posterior junctional anchor suture was then placed and used to attach the allograft to remaining native labrum followed by final tightening of all sutures for full seating of the MAT (Fig. 1).
• •Tendon allograft transplant (TAT) – A fresh-frozen anterior tibialis tendon allograft was prepared by trimming its length to match the defect. The labral defect was matched with a fresh frozen anterior tibialis allograft. Nonabsorbable #2 suture was placed at each end of the graft and then 1 cm intervals. Knotless suture anchors placed at the margins (anterior and posterior) of the labral defect and at 1 cm intervals along the recipient bed while the graft was being prepared. Allograft fixation was performed from anterior to posterior using each pre-placed anchors. The allograft was repaired to remaining native labrum using a 2-0 absorbable suture. The hip was then reduced (Fig. 1). After capsular repair, the greater trochanter was repaired with independent cortical screw fixation with washers, followed by routine closure of the surgical wounds. Patients were admitted to the inpatient care unit for 12–72 h for intravenous antibiotics, pain management, and safety and precaution education and training. Patients were discharged with verbal and written instructions regarding postoperative restrictions, wound care, and follow-up appointments after they were cleared by physical therapy and had their pain controlled with oral medications.

Fig. 1.

Illustration of the technique for allograft preparation (A), acetabular recipient bed preparation (B), and allograft fixation (C) for reconstruction of an irreparable labral defect using fresh medial meniscus allograft transplantation (MAT, D-G) or fresh-frozen tendon allograft transplantation (TAT, D-G).

2.3. Postoperative management (see supplement)

Patients were prescribed a procedure-specific restriction and rehabilitation protocol. A physical therapist met with patients during their inpatient hospital stay to educate and guide them on mobility training and review instructions for restrictions, outpatient physical therapy, and home exercise. Physical therapists from the author's institution attended each patient's pre- and post-operative clinic visits and communicated with their outpatient physical therapist to ensure adherence with the prescribed protocol. Patients were initially restricted to 25 pounds flat foot weight bearing with use of bilateral crutches for ambulation for the first 6 weeks after surgery. In addition to hip range of motion (ROM) restrictions during the first 6 weeks, patients were also restricted from active hip abduction to avoid stress to the greater trochanter osteotomy. Patients were instructed to begin outpatient physical therapy within the first 2 weeks of surgery. Early PT intervention included active and passive hip ROM within the protocol parameters, isometric muscle activation, and stationary cycling (recumbent or upright). Clearance for progression of weight bearing was based on radiographic evidence of healing of the greater trochanter osteotomy, typically at 6 weeks postoperatively. For patients that had a concurrent femoral head OCA, the progression to full weight bearing typically occurred over a longer period. Patients were encouraged to utilize crutches until they could demonstrate a normal gait pattern without assistive device. Closed chain strengthening was initiated after patients were cleared for full weight bearing. Patients could begin elliptical training at 3 months and were cleared to resume sports at 6 months after surgery. Determination for return to sport was based on subjective and objective assessments. Adherence with the prescribed restriction and rehabilitation protocol was determined and documented based on patient's subjective reports and outpatient physical therapist's communications.

2.4. Outcome measures

Pre-operatively and at 6 weeks, 3 months, 6 months, and then yearly following surgery, patient reported outcome measures (PROMs) were collected using electronic data capture into a secure HIPAA- and HITECH-compliant database (PatientIQ). Collected PROMs included visual analog scale for pain (VAS),⁴⁹ Hip disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS-JR),⁵⁰ and Patient Reported Outcomes Measurement Information System Physical Function (PROMIS PF) scores.⁵¹ Electronic medical records were used to retrieve patient demographic, operative, complications, and re-operations data. The authors defined treatment failure as revision surgeries that involved the affected hip or conversion to total hip arthroplasty (THA). Decisions to pursue revision or THA were made by the patient after discussion with the attending surgeon regarding reason for failure, treatment options, and prognosis. Outcomes were categorized as successful when patients returned to functional activities without revision or arthroplasty at final follow-up. Initial success rate was calculated as: 100% - (%revision + %THA). A subset of patients in each cohort consented to IRB-approved (#2014820) research MRI of the affected hip performed at least 6 months after labrum reconstruction in order to contribute to scientific knowledge and receive further details regarding their post-operative hip status. All patients were imaged using a 1.5 T magnet (Signa Artist GE Healthcare, United States). Sequences obtained included axial and coronal T1-weighted images, coronal STIR and intermediate-weighted images with fat saturation, sagittal T2-weighted fat suppressed images and axial oblique T2-weighted fat saturated images with a field of view of 18 cm for the affected hip and a matrix of 288x192 and slice thickness of 3.5–4 mm.

All MRI exams were interpreted by a fellowship-trained musculoskeletal radiologist with 25 years’ experience (RW) blinded to patient demographics, graft type, and outcomes to provide subjective assessments of allograft integrity, integration, signal, and structure. A labral tear was defined as abnormal fluid signal either within the labrum or traversing the entire labral-acetabular junction. Fraying and partial tear were defined as irregular morphology or intra-meniscal signal not indicative of fluid.

2.5. Statistical analysis

Case inclusion for statistical analyses was based on availability of complete data for patients who underwent ALR with at least 1-year of follow-up. Means, standard deviations (SD), ranges, and percentages were calculated. Outcomes were compared between cohorts based on differences in allograft type, defined as TAT versus MAT. Differences in proportions were analyzed using Fisher exact tests and when significant differences were noted, odds ratios were calculated for relevant comparisons with the Haldane-Anscombe correction used for zeroes. For comparisons at each time point, t-Tests (continuous data) or rank sum tests (categorical data) were used. For assessments over time within each cohort, repeated measures analysis of variance was used. Significance was set at P < 0.05.

3. Results

3.1. Patient variables

In total, 27 ALR patients (15 female, 12 male) met all criteria for analysis. Mean age was 30.7 years (SD: 9.2, range: 18–48) and mean body mass index (BMI) was 27.1 kg/m2 (SD: 5.4, range: 20.1–44.0) (Table 1).

Table 1.

Comparison of patient variables for fresh-frozen tendon allograft (TAT) and fresh meniscus allograft (MAT) transplant for acetabular labrum reconstruction cohorts.

Variable	MAT	TAT	p value
	n = 22	n = 5
Age, years (sd)	31.9 (9.3)	25.4 (7.0)	0.07
Sex (%)	male: 10 (45.5%) female: 12 (54.5%)	male: 2 (40.0%) female: 3 (60.0%)	1
BMI, kg/m2(sd)	26.9 (5.8)	28.1 (3.8)	0.35
Nicotine Use (%)	1 (4.5%)	1 (20.0%)	0.24
Concurrent Procedures (%)	8 (36.4%)	5 (100%)	0.016
Nonadherent (%)	5 (22.7%)	0 (0%)	0.25
Treatment Failure (%)	2 (9.1%)	1 (20.0%)	0.47
Final Follow-up, months (range)	26.8 (12–46)	59.6 (18–79)	0.13

Key: MAT = meniscal allograft transplant, TAT: tendon allograft transplant, BMI: Body mass index, sd = standard deviation, % = percentage of cohort.

Five patients (3 female, 2 male) with mean age of 25.4 years (SD: 7.0, range: 19–33) and mean BMI of 28.1 kg/m2 (SD: 3.8, range 24–31.6) were included in the TAT cohort. All five TAT patients underwent concurrent femoral head OCA transplantation at time of labral allograft reconstruction. Mean follow-up in this cohort was 59.6 months (range 18–79). The MAT cohort included 22 patients (12 female, 10 male) with mean age of 31.9 years (SD: 9.3, range 18–48) and mean BMI of 26.9 kg/m2 (SD: 5.8, range: 20.1–44.0). Five MAT patients underwent concurrent femoral head OCA transplantation and three underwent PFRO at time of labral allograft reconstruction. Mean follow-up in this cohort was 26.8 months (range: 12–46). When OCA transplantation and PFRO were combined, patients in the TAT cohort had a significantly higher proportion of concurrent surgical procedures performed (p = .016). No other statistically significant differences between cohorts were noted for patient variables assessed.

3.2. Treatment success/failure

For all patients combined, 24 of 27 patients (88.9%) were categorized as having successful outcomes. For the TAT cohort, initial success rate was 80% with one patient undergoing THA 4 months after labrum reconstruction. For the MAT cohort, initial success rate was 90.1% based on two patients undergoing THA; one at 9 months and one at 38 months after labrum reconstruction. This difference in initial treatment success rates between cohorts was not statistically significant (p = .47). All three treatment failures were attributed to avascular necrosis, femoral head collapse, and/or acetabular cartilage loss in association with femoral head OCA transplantation that was performed for concurrent treatment of joint co-morbidities. Based on diagnostic imaging and intra-operative assessments, none of the treatment failures were attributable to acetabular labrum allograft reconstruction.

3.3. Risk factors for treatment failure

There was a significant association between treatment failure and concurrent femoral head OCA transplantation (p = 0.029, OR = 19.9). Patient age, sex, BMI, and nicotine use, labrum allograft type, and adherence were not significantly associated with increased risk for treatment failure.

3.4. Patient reported outcome measures (Table 2)

Table 2.

Mean (±SD) patient reported outcomes for fresh meniscus allograft transplant (MAT) and fresh-frozen tendon allograft transplant (TAT) for acetabular labrum reconstruction cohorts.

Outcome Measure (sd)	Cohort	Pre-Op	3 Month Follow-Up	6 Month Follow-Up	1 Year Follow-Up	Final Follow-Up
HOOS Jr	MAT	60.1 (11.9)	62.1 (15.1)	72.6 (17.4)	80.4 (16.0)	76.8 (17.4)
	TAT	41.5 (5.8)	62.1 (15.3)	87.8 (14.7)	80.9 (27.0)	72.4 (12.4)
VAS Pain	MAT	5.1 (2.1)	2.9 (1.8)	3.6 (2.7)	1.8 (1.9)	2.1 (1.9)
	TAT	6 (0.8)	3.5 (4.0)	0 (0)	1.5 (2.1)	3.3 (3.4)
PROMIS Physical Function	MAT	40.6 (8.2)	38.7 (7.2)	40.9 (7.2)	46.8 (6.6)	48 (8.2)
	TAT	48.7 (32.0)	37.4 (11.4)	37.4 (11.4)	42.5 (9.7)	42.5 (7.0)

Key: MAT = meniscal allograft transplant; TAT: tendon allograft transplant; HOOS Jr = Hip disability and Osteoarthritis junior; VAS = Visual Analog Pain, sd = standard deviation.

In the MAT cohort, improvements in VAS pain (p < 0.001, p < 0.001), HOOS-JR (p = 0.004, p = 0.023), and PROMIS PF (p = 0.044, p = 0.035) scores, which were clinically meaningful and statistically significant, were noted at one year and FFU.^52,53 Improvements in VAS pain scores, which were also clinically meaningful and statistically significant for the TAT group, were noted at 1-year (p < 0.001). However, these scores were not sustained at final follow-up (p = 0.31), while HOOS-JR scores were not significantly improved at the one year mark (p = 0.10), but had significantly improved at final follow-up (p = 0.03).^52,53 Compared to pre-operative scores, PROMIS PF scores were lower at 1-year and FFU and were not within 1 standard deviation of the health population mean in the TAT cohort. However, none of the longitudinal differences noted were statistically significant for the TAT cohort and no statistically significant differences between cohorts were noted for measured PROMs.

3.5. Subjective MRI assessments (Fig. 2)

Fig. 2.

Representative magnetic resonance images for fresh medial meniscus allograft transplantation (MAT)(A - coronal Intermediate fat suppressed) and fresh-frozen tendon allograft transplantation (TAT)(B - coronal T1-weighted image) for acetabular labrum reconstruction. Arrowhead - MAT acetabular labrum reconstruction demonstrating allograft integrity, integration with acetabular rim, homogeneous connective tissue signal, and triangular-shaped tissue in close approximation with the femoral head. Arrow – intact oval-shaped TAT acetabular labrum reconstruction demonstrating integration to acetabular rim with inhomogeneous signal, fibrillation, horizontal intermediate signal cleft in the lateral edge of the labrum consistent with a partial tear, and lack of close approximation with the femoral head.

MRI of MAT acetabular labrum reconstructions performed 6–29 months after transplant were consistently associated with allograft integrity, integration with acetabular rim and native labrum, homogeneous connective tissue signal, and triangular-shaped tissue in close approximation with the femoral head contour on coronal views. Four allografts (28.6%) in the MAT cohort had MRI findings consistent with mild fraying/partial superficial tears of the superior aspect of a portion of the graft. MRIs of TAT acetabular labrum reconstructions performed at 6 and 29 months after transplant demonstrated intact allografts with integration to acetabular rim and native labrum, an oval shape with inhomogeneous signal, fibrillation and/or partial tearing, and lack of close approximation with the femoral head contour on coronal views.

4. Discussion

The data from this study suggest that patients undergoing open acetabular labral reconstructions using MAT may have better initial outcomes (∼24 months) when compared to those using TAT based on diagnostic imaging assessments as well as patient-reported pain and function scores. Patients undergoing acetabular labral reconstruction with MAT were associated with successful outcomes in 90.9% of cases, reporting significantly improved pain, HOOS JR, and PROMIS Physical Function scores through at least 1-year after labral reconstruction. Patients undergoing acetabular labral reconstruction with TAT were associated with successful outcomes in 80% of cases, and while pain and HOOS JR scores improved, PROMIS Physical Function scores declined in the TAT cohort. The outcomes for the TAT cohort are similar to those previously reported for acetabular labral reconstruction utilizing grafts of various types^2,24,34,36 while short-term outcomes after MAT acetabular labrum reconstruction were associated with better patient reported scores, subjective MRI findings, and success rate. The key differences between MAT and TAT for acetabular labrum reconstruction that may influence outcomes could be related to biologic (e.g., cell viability and metabolism, tissue composition and physiology) and biomechanical (e.g., size, shape, and geometry, architecture, and material properties) variables. Fresh meniscus allografts contain viable fibrochondrocytes embedded in a fibrocartilage extracellular matrix with vascular and avascular zones that have biochemical and structural compositions and material properties that are similar to acetabular labrum.^10,36 Fresh-frozen tendon allografts do not contain viable cells and must undergo cellular re-population and phenotypic shifts in order to synthesize and remodel extracellular matrix that can functionally recapitulate acetabular labrum.^14,27,34 The subjective MRI assessments performed in the present study suggest that these contrasting characteristics and processes may have resulted in differences in allograft composition, shape, and function after transplantation for acetabular labral reconstruction. Based on these diagnostic imaging differences in conjunction with differing functional outcomes as well as preclinical and clinical data supporting the safe and effective use of fresh meniscus allografts for meniscus transplantation^36,42 including via an arthroscopic technique,⁵⁴ fresh MAT for acetabular labrum reconstruction warrants consideration as a preferred option when indicated. However, further research is necessary to determine if these differences are directly related to improved functional outcomes in patients.

When considering the entire study population, failure was not significantly associated with patient age, graft type, patient BMI, secondary procedures, or nicotine use. However, there was a statistically significant association for treatment failure with concurrent femoral head OCA transplantation. All three treatment failures in the present study were attributed to avascular necrosis, femoral head collapse, and/or acetabular cartilage loss in association with femoral head OCA transplantation rather than being directly attributable to acetabular labrum allograft reconstruction. As such, the differences in outcomes noted between TAT and MAT cohorts may be more related to the significantly higher proportion of concurrent surgical procedures performed in the TAT cohort than to allograft type or reconstruction technique. Interestingly, while other studies⁴⁵ have reported non-adherence with the prescribed post-operative restriction and rehabilitation protocol to significantly increase risk for failure after OCAT and/or MAT and 18.5% patients in the present study were documented to be non-adherent with the prescribed protocol, non-adherence was not associated with a statistically significant increase in likelihood for treatment failure in the study population. However, this lack of statistical significance should not devalue the importance of post-operative adherence such that patient education, counseling, and support for optimizing adherence should still be considered standard of care for these transplant procedures.⁴⁵ Study limitations should be considered for any applications of the results to clinical practice. Treatment cohort was not randomized, and the study population was relatively limited with only a very small number of patients included in the TAT cohort based on the evidence-based shift in practice toward use of MAT for acetabular labrum reconstruction at our institution. Further, only two of the TAT patients underwent post-transplant MRI for subjective assessments of labrum reconstruction. In addition, only short-term outcomes for open-approach labrum reconstruction performed by one surgeon were analyzed. Finally, there was a significant difference in the proportion of concurrent surgical procedures performed between cohorts. As such, the results of the present study are not generalizable to other surgeons, institutions, or patient populations or applicable to arthroscopic techniques or other graft types, and the lack of statistically significant differences within or between cohorts are likely due to type II errors. As such, conclusions are limited to potential differences that warrant further investigation. 337 The results of the present study suggest that fresh meniscus allografts can be an option for acetabular labrum reconstruction. As demonstrated, MAT for acetabular labrum reconstruction showed improved short-term patient reported scores, subjective MRI findings, and success rate compared to TAT. Biologic and biomechanical differences in graft types and surgical transplantation techniques may influence these differences. There was a significantly higher treatment failure rate with concurrent femoral head OCA transplantation, such that further research is necessary to determine if MAT has any direct effects on improved functional outcomes after acetabular labrum reconstruction.

Ethical statement

This study received approval from the Institutional Review Board of the University of Missouri Columbia (IRB ##2003053).

Funding statement

No external funding was used in the completion of this study.

Guardian/patient's consent

The patients and/or their families were informed that data from the research would be submitted for publication, and gave their consent.

CRediT authorship contribution statement

James L. Cook: Conceptualization, Data curation, Formal analysis, Funding acquisition, Investigation, Methodology, Project administration, Supervision, Validation, Writing – original draft, Writing – review & editing. Kylee Rucinski: Data curation, Formal analysis, Investigation, Methodology, Validation, Writing – original draft, Writing – review & editing. Robert Wissman: Formal analysis, Investigation, Methodology, Writing – review & editing. Cory Crecelius: Data curation, Investigation, Writing – review & editing. Steven DeFroda: Investigation, Methodology, Writing – review & editing. Brett D. Crist: Conceptualization, Data curation, Funding acquisition, Investigation, Methodology, Project administration, Supervision, Writing – review & editing.