Purpose

Osteochondral allograft transplantation has a demonstrated survivorship of upwards of 90% in the first five years following surgery. Although OCAs are highly effective, in some cases, subsequent surgeries may be required. There is currently limited data on the risk factors for reoperations following OCA and the interventions ultimately required. The purpose of this study was to utilize a large insurance database to evaluate the risk factors for failure within five years of OCA transplantation.

Methods and Materials

We queried the MarketScan database from 2007-2015 to identify patients who underwent primary OCA. Patients with previous ipsilateral anterior cruciate ligament reconstruction or meniscus surgery were excluded. Baseline demographic data and patient co-morbidities were documented. Failure of OCA, which we defined as ipsilateral revision OCA or conversion to unicomparmental or total knee arthroplasty, was documented through 5-years following index OCA. Multivariate regression analyses were conducted to identify risk factors for failure.

Results

A total of 1428 patients were included in the study. Mean age of the cohort was 31.6 years (SD 12.1) with 41.2% of the cohort being female. 9.7% of the cohort was obese at the time of initial OCA, 7.5% were active smokers, and 15.5% of the cohort had a previous cartilage restoring procedure. 0.3% underwent a revision or arthroplasty procedure within 5-years. Female sex (OR 1.61) and a history of microfracture prior to OCA (OR 1.21) increased risk for OCA failure. Concomitant osteotomy at the time of index OCA decreased odds of failure (OR 0.4, p – 0.0366).

Conclusion

Female sex and a history of microfracture increased odds for OCA failure, whereas a concomitant osteotomy at time of index surgery improved survivorship. This data should factor into a surgeon’s decision making when considering OCA for their patients with chondral defects of the knee.

Purpose

To evaluate anatomic factors of donor and recipient trochleae associated with osteochondral allograft matching for superolateral and central defects in a computer-simulated model.

Methods and Materials

Ten cadaveric trochlear specimens were utilized for this study. Three-dimensional (3D) point cloud models of the trochleae were created using a segmentation software program from CT scans (Mimics, Materialise Inc., Leuven, Belgium). Circular defect models were created virtually at both superolateral (18mm and 22.5mm) and central (18mm, 22.5mm, 30mm) locations. The mean articular step-off was calculated along the periphery of the graft. Demographic and anatomic factors measured include age, sex, laterality, lateral facet width, medial facet width, lateral condyle radius of curvature, trochlear groove radius of curvature, tibial width, trochlear length, and trochlear width. Sulcus angle and sagittal angle at the center of the defect and grafts for the central trochlear location were calculated by a custom-designed program.

Results

On multivariate analysis, sulcus angle difference (β=0.019, p=0.002), sagittal angle difference (β=0.018, p=0.001), and lateral condyle radius of curvature (β=0.015, p=0.003) were significant predictors of articular step-off for 18mm central defects (R2=0.45). For 22.5mm central defects, sulcus angle difference (β=0.029, p<0.001), sagittal angle difference (β=0.025, p<.001), medial facet width (β=0.026, p=0.021), and lateral radius of curvature (β=0.013, p=0.025) were significant. Similarly, for 30mm central defects, sulcus angle difference (β=0.03, p=0.001), lateral radius of curvature (β=.032, p=0.004), and trochlear length (β=0.041, p<0.001), were significant predictors. For 18mm superolateral defects, no significant predictors were identified on multivariate analysis. For 22.5mm superolateral trochlear defects, medial facet width (β=.006, p<0.001) and trochlear length (β=.002, p=0.003) were significantly associated.

Conclusion

Minimizing mismatch in anatomic factors such as sulcus angle, sagittal angle, lateral condyle radius of curvature, and medial facet width may contribute to more optimal graft matching.

Purpose

The clinical feasibility of thin osteochondral allografts for cartilage repair can benefit from cryopreservation to extend the shelf life of the implants. It is critical to consider the effects of cryopreservation on the mechanical properties of cartilage. The purpose of this study was to compare the viscoelastic mechanics of fresh and cryopreserved allografts via indentation stress-relaxation testing.

Methods and Materials

1mm thick cartilage sheets 20mm in diameter (AlloSource, Centennial, CO, USA) were prepared from weight bearing joints of eight research consented cadaveric human donors. Fresh grafts were aseptically packaged in media and stored at 4°C for 14-25 days until tested. Donor-matched grafts were cryopreserved following a proprietary process using a common cryoprotectant and stored at -80°C until tested. Specimens were hydrated by frequent saline spray and underwent indentation testing at room temperature using a 0.8mm diameter spherical tip displaced 0.1mm into the sample at a rate of 0.1mm/s; this displacement was held for a 100s relaxation period (Figure 1). Indentation repetitions were conducted at three locations per specimen. Elastic moduli were calculated using Hertzian contact mechanics formulae.

Results

Differences between fresh and cryopreserved means fell within one standard deviation for all parameters (Table 1). There was no consistent effect of cryopreservation on the mechanical properties when comparing specimens from individual donors (Figure 2). Accordingly, there were no significant differences from paired t-tests (α=0.05) between fresh and cryopreserved groups in instantaneous modulus (P =.18), equilibrium modulus (P =.36), or percent relaxation (P =.69).

Conclusion

The data from this study indicated no significant differences in the instantaneous and time-dependent (viscoelastic) mechanical properties derived from indentation tests between fresh and cryopreserved ProChondrixCR® allografts.

Purpose

Determine the most suitable graft options for osteochondral allograft transplantation of a large MFC defect

Methods and Materials

120 fresh frozen human femoral condyles were matched into 30 groups of four condyles (1 MFC recipient, 3 donor condyles). OCA transplants were done on 17x36 mm defects in MFCs using orthotopic MFC, non-orthotopic LFC, and oerlapping OCA plugs. Specimen were analyzed with a nano-CT to assess contour and surface step-off. Dragonfly 3D and Excel were used to determine the root mean square (RMS) of both the surface height deviation and circumferential step-off height deviation between the native and donor cartilage surfaces.

Results

All three graft options successfully restored the surface contour within acceptable limits without signficant differences between graft source. Oval LFC and MFC grafts had less step-off height differences than overlapping cylindrical plugs.

Conclusion

Oval MFC & LFC OCA grafts produce a significantly better surface contour and graft:native cartilage interface match to the native MFC than mastercard grafts for oval defects. Contralateral LFC grafts are acceptable graft option for large MFC defects.

Purpose

Successful outcomes of meniscal allograft transplantation are dependent on adequate size matching of donor and patient meniscus. The extent that donor pools meet the demands of the patient pool is unknown. The purpose of this study was to analyze the variability in meniscus size and anthropometric data between donors (supply) and patients (demand), and determine the impact on time to match.

Methods and Materials

Lateral and medial meniscal measurements, sex, patient height and weight, and time to match a donor graft were extracted from a tissue supplier database. Distributions of meniscus size for patient and donor pools were analyzed. Body Mass Index (BMI), meniscus area, body mass to meniscus area index (BMMI), and height to meniscus area index (HMI) were compared via chi-square tests and independent samples t-test. The effect of size on time to match was analyzed using ANOVA and post-hoc Tukey test.

Results

The distributions of meniscus sizes were significantly different for meniscus donor and patient populations (Fig1A-D). The lateral meniscus patients showed a higher frequency of larger size meniscus and the medial meniscus patients showed a higher frequency of smaller size meniscus. The lateral meniscus analysis showed significantly greater meniscus area and increased average height in the patient population. The medial meniscus analysis showed significantly smaller meniscus areas in the patient population contributing to an increased BMMI and HMI. The time to match a donor meniscus was affected by the patient meniscus size.

Figure 1: Distribution of donor (blue) and patient (gray) meniscus sizes.

Conclusion

This analysis demonstrates variations in frequency of meniscus sizes between donor and patient populations. This variation is attributed to significant differences in anthropometric data between patient and donor populations. This work identifies a mismatch between demand and supply. Areas of size mismatch were further substantiated by the longer time period to identify a donor match.

Purpose

The purpose of this study was to investigate the effect of bone marrow aspirate concentrate (BMAC) on osseointegration and patient-reported outcome metrics (PROMs) after osteochondral allograft transplantation in a prospective, randomized controlled single-blinded trial.

Methods and Materials

Patients undergoing osteochondral allograft transplantation of the knee were consented and enrolled. Prior to surgery, patients were randomized into either the BMAC or sham incision groups. In the BMAC group, the osteochondral allograft plug was soaked in BMAC for a minimum of 2 minutes prior to implantation. All patients underwent postoperative computed tomography (CT) scanning at 6 months postoperatively and completed PROMs preoperatively, 6 months, and 1 year postoperatively. Two board-eligible orthopaedic surgeons blinded to treatment allocation independently assessed and graded each CT according to the ACTOCA system proposed by Gelber et al.

Results

Thirty-six patients enrolled between April 2018 to December 2020 (17 female, 19 male) were included for analysis. There were no significant differences between the BMAC and non-BMAC groups in graft signal density (Grader 1: p=0.283, Grader 2: p=0.467), osseous integration (both graders: p=0.489), surface percentage with discernible cleft (Grader 1: 0.287, Grader 2: 0.469), or intra-articular fragments (Grader 1: p=0.617, Grader 2: p=0.810) (Table 1). Significantly fewer patients receiving BMAC demonstrating cystic changes >3 mm (Grader 1: p=0.015, Grader 2: p=0.05) (Figure 1). At 1 year, BMAC patients reported significantly better WOMAC Pain (87.82±14.26 vs 75.80±15.56, p=0.043) and trended towards improved PROMIS Pain (54.14±8.31 vs 61.79±5.24, p=0.09).

Conclusion

Patients receiving BMAC soaked OCA grafts demonstrated no difference from controls with respect to graft signal intensity, osseous integration, intra-articular fragments, or discernible graft-host clefts at 6-months postoperatively. BMAC patients had a significantly lower occurrence of large (>3 mm) cystic changes. At 1 year, BMAC patients reported significantly less pain than controls on WOMAC Pain, with similar trends on PROMIS Pain Interference.

Purpose

Sex mismatch between donor and recipient has been considered a potential contributor to adverse outcomes following solid organ transplantation. However, the influence of sex mismatching in osteochondral allograft (OCA) transplantation is yet to be determined. The purpose of this study was to evaluate whether donor-recipient sex mismatching impacts graft survival after OCA transplantation.

Methods and Materials

Patients who underwent OCA transplantation between November 2013 and November 2017 by a single surgeon were included. Cumulative survival was performed through the Kaplan–Meier method using log-rank tests to compare patients with similar donor groups. Multivariable Cox regression analysis adjusted for patient age, graft size and BMI were used to evaluate the influence of donor-recipient sex on graft survival.

Results

A total of 154 patients were included, 102 (66.2%) who received OCAs from a same-sex donor, and 52 (33.8%) from a different sex donor. At 5 years follow-up, a significantly lower graft survival rate was observed for different-sex donor transplantation in comparison to the same-sex donors (63% versus 92%, p=0.01). When correcting for age, graft size and BMI, donor-recipient sex mismatching demonstrated a 2.9 times greater likelihood to fail at 5 years compared to the donor-recipient same-sex (p=0.03). A subgroup analysis showed no significant difference in graft survival between female-to-female and female-to-male groups (91% and 84%, respectively). Conversely, male-to-male demonstrated a significantly higher cumulative 5-year survival (94%, p=0.04), whereas a lower survival was found in the male-to-female group (64%, p = 0.04). Multivariable Cox regression indicated a 2.6 times higher likelihood of failure for male-to-female in comparison with other groups (p=0.04). Male-to-male had a tendency toward the decreased likelihood of OCA failure (0.33 hazard ratio), although without statistical significance (p=0.052).

Conclusion

Mismatch between donor and recipient sex has a negative effect on OCA survival following transplantation, particularly in those cases when male donor tissue was transplanted into a female recipient.

Purpose

In cases of large osteochondral lesions of the talus (OLT), fresh structural or bulk osteochondral allograft transplantation has yielded favorable outcomes in several case series. The purpose of this study was to prospectively evaluate patients who received fresh, structural allograft transplantation of the talar shoulder.

Methods and Materials

A prospective evaluation of patients who received a fresh, structural allograft of an osteochondral lesion of the talus (OCLT) was performed. Preoperative imaging with magnetic resonance imaging (MRI) and/or computed tomography (CT) with plain radiographs were obtained. Patient-reported outcome questionnaires were administered preoperatively and annually postoperatively to include: 100-mm visual analog scale (VAS) pain scale, American Orthopaedic Foot & Ankle Society (AOFAS) Ankle-Hindfoot Scale, Short Form 36 (SF-36), and the Short Musculoskeletal Functional Assessment (SMFA). Imaging was evaluated for allograft assimilation, arthritic changes or functional range of motion abnormalities.

Results

Thirty-one patients with an average age of 41.4 (± 14.1), 17 being female patients (54.8%) and 14 (46.2%) being male patients, with a mean follow-up of 56.2 months (± 36.1) underwent structural fresh osteochondral allograft transplantation to the talar shoulder from January 1, 2007 to August 1, 2019. The mean lesion size on CT scan was 1,879 mm3 (n=27) and 3,877 mm3 (n= 21) on MRI. There was a significant improvement in the mean preoperative VAS score (<0.0001), AOFAS score (<0.0001), SF-36 score (<0.0005), SMFA Bother index (<0.0015), and the SMFA Function index (<0.0001) at final follow-up. A total of 15 (48.4%) patients underwent an additional surgery following their osteochondral allograft transplant most commonly arthroscopy or removal of hardware. The overall graft survival rate was 96.8% at an average of 4.5 years postoperatively.

Conclusion

Fresh, structural allograft transplantation in cases of large OLT resulted in a significant improvement in postoperative pain and function. This procedure offers a promising alternative for significant osteochondral lesions of the talar shoulder.

Purpose

To evaluate survivorship, patient satisfaction, and long-term functional outcomes of humeral head osteochondral allograft (OCA) transplantation in patients with isolated focal chondral defects.

Methods and Materials

A registry of consecutive patients undergoing humeral head OCA transplantation between 2004 and 2012 was retrospectively reviewed. Treatment failure was defined as conversion to total shoulder arthroplasty (TSA). Patients completed Simple Shoulder Test (SST), American Shoulder and Elbow Surgeons Shoulder Score (ASES), and Short Form 12 (SF-12) Physical and Mental outcome assessments. Patient satisfaction and sport activity outcomes were also assessed. Postoperative outcomes were compared to baseline scores using Student’s t-tests with statistical significance defined as P<0.05.

Results

20 patients were identified, of which 13 (65%) had completed follow-up and were included in the analysis. Five patients (38.6%) failed treatment and underwent TSA at an average 3.91 ± 4.25 years (range 0.97-11.0) after index surgery. The average follow-up of the remaining eight patients (4 females, 4 males, mean age 26.8 ± 10.2 years) was 12.0 ± 3.1 years (range 7.6-15.7 years). Mean scores of all outcome assessments were higher at final follow-up than at baseline, but the difference was significant only in SST scores (Table 1). Patient satisfaction varied, with four patients reporting extreme satisfaction, one reporting moderate satisfaction, two reporting somewhat satisfaction, and one reporting no satisfaction. Only three of the eight patients were able to return to sport, two at the same level of competition and one at a lower level of competition.

Conclusion

The results of this case series suggest that the reported short and mid-term outcome improvements of humeral head OCA transplantation diminish at long-term time points. Moreover, athletes should be counseled on sport activity outcome probabilities. Despite these limitations, patient satisfaction rates with regards to long-term outcomes are generally favorable.