Large fresh osteochondral allografts of the knee: a systematic clinical and basic science review of the literature

Bulk Osteochondral Allograft for a Firearm Injury to the Medial Femoral Condyle in a Military Service Member: A Case Report

A 27-year-old U.S. military active duty male sustained an accidental, self-inflicted left knee gunshot injury with an unsalvageable medial femoral condyle injury. The patient underwent bulk osteochondral allograft transplantation. Nine months post-operation, the patient was fit for full military duties with no reported functional limitations and remained on active duty. Severe knee medial femoral condyle bone loss after accidental firearm injury is uncommon. Bulk knee osteochondral allograft transplantation to the medial femoral condyle provided a successful treatment option for an active duty U.S. military member with multicompartment osteochondral defects and severe medial femoral condyle bone loss due to a gunshot injury.

Composition, architecture and biomechanical properties of articular cartilage in differently loaded areas of the equine stifle

BACKGROUND

Strategies for articular cartilage repair need to take into account topographical differences in tissue composition and architecture to achieve durable functional outcome. These have not yet been investigated in the equine stifle.

OBJECTIVES

To analyse the biochemical composition and architecture of three differently loaded areas of the equine stifle. We hypothesise that site differences correlate with the biomechanical characteristics of the cartilage.

STUDY DESIGN

Ex vivo study.

METHODS

Thirty osteochondral plugs per location were harvested from the lateral trochlear ridge (LTR), the distal intertrochlear groove (DITG) and the medial femoral condyle (MFC). These underwent biochemical, biomechanical and structural analysis. A linear mixed model with location as a fixed factor and horse as a random factor was applied, followed by pair-wise comparisons of estimated means with false discovery rate correction, to test for differences between locations. Correlations between biochemical and biomechanical parameters were tested using Spearman's correlation coefficient.

RESULTS

Glycosaminoglycan content was different between all sites (estimated mean [95% confidence interval (CI)] for LTR 75.4 [64.5, 88.2], for intercondylar notch (ICN) 37.3 [31.9, 43.6], for MFC 93.7 [80.1109.6] μg/mg dry weight), as were equilibrium modulus (LTR2.20 [1.96, 2.46], ICN0.48 [0.37, 0.6], MFC1.36 [1.17, 1.56] MPa), dynamic modulus (LTR7.33 [6.54, 8.17], ICN4.38 [3.77, 5.03], MFC5.62 [4.93, 6.36] MPa) and viscosity (LTR7.49 [6.76, 8.26], ICN16.99 [15.88, 18.14], MFC8.7 [7.91,9.5]°). The two weightbearing areas (LTR and MCF) and the non-weightbearing area (ICN) differed in collagen content (LTR 139 [127, 152], ICN176[162, 191], MFC 127[115, 139] μg/mg dry weight), parallelism index and angle of collagen fibres. The strongest correlations were between proteoglycan content and equilibrium modulus (r: 0.642; p: 0.001), dynamic modulus (r: 0.554; p < 0.001) and phase shift (r: -0.675; p < 0.001), and between collagen orientation angle and equilibrium modulus (r: -0.612; p < 0.001), dynamic modulus (r: -0.424; p < 0.001) and phase shift (r: 0.609; p < 0.001).

MAIN LIMITATIONS

Only a single sample per location was analysed.

CONCLUSIONS

There were significant differences in cartilage biochemical composition, biomechanics and architecture between the three differently loaded sites. The biochemical and structural composition correlated with the mechanical characteristics. These differences need to be acknowledged by designing cartilage repair strategies.

Effect of Press-Fit Size on Insertion Mechanics and Cartilage Viability in Human and Ovine Osteochondral Grafts

OBJECTIVE

The osteochondral allograft procedure uses grafts constructed larger than the recipient site to stabilize the graft, in what is known as the press-fit technique. This research aims to characterize the relationships between press-fit size, insertion forces, and cell viability in ovine and human osteochondral tissue.

DESIGN

Human (4 donors) and ovine (5 animals) articular joints were used to harvest osteochondral grafts (4.55 mm diameter, N = 33 Human, N = 35 Ovine) and create recipient sites with grafts constructed to achieve varying degrees of press fit (0.025-0.240 mm). Donor grafts were inserted into recipient sites while insertion forces were measured followed by quantification of chondrocyte viability and histological staining to evaluate the extracellular matrix.

RESULTS

Both human and ovine tissues exhibited similar mechanical and cellular responses to changes in press-fit. Insertion forces (Human: 3-169 MPa, Ovine: 36-314 MPa) and cell viability (Human: 16%-89% live, Ovine: 2%-76% live) were correlated to press-fit size for both human (force: r = 0.539, viability: r = -0.729) and ovine (force: r = 0.655, viability: r = -0.714) tissues. In both species, a press-fit above 0.14 mm resulted in reduced cell viability below a level acceptable for transplantation, increased insertion forces, and reduced linear correlation to press-fit size compared to samples with a press-fit below 0.14 mm.

CONCLUSIONS

Increasing press-fit size required increased insertion forces and resulted in reduced cell viability. Ovine and human osteochondral tissues responded similarly to impact insertion and varying press-fit size, providing evidence for the use of the ovine model in allograft-related research.

Acellular Aragonite-Based Scaffold for the Treatment of Joint Surface Lesions of the Knee: A Minimum 5-Year Follow-Up Study

OBJECTIVE

A novel aragonite-based scaffold has been developed. In this study, mid-term clinical and magnetic resonance imaging (MRI) results on 12 patients affected by isolated chondral or osteochondral lesions of the knee treated by the scaffold implantation have been evaluated at a mean follow-up of 6.5 (range: 5-8) years.

DESIGN

The study population consisted of 3 females and 9 males, mean age 34.4 (20-51) years. The lesion was located on the medial femoral condyle, the trochlea, and the lateral femoral condyle in 5, 5, and 2 patients, respectively. In all cases, a single lesion over grade 3 of the International Cartilage Restoration and Joint Preservation Society (ICRS) classification was treated: in 9 cases by implantation of one plug, and in 2 cases with 2 plugs; the mean size of the lesion was 2.5 cm2 (1-7).

RESULTS

One patient failed and was revised with a custom-made metal implant (Episealer). Overall, Knee Injury and Osteoarthritis Outcome Score (KOOS) significantly improved from 45 ± 13 preoperatively to 86 ± 13 at final follow-up. All KOOS subscales improved significantly: pain subscale increased from 48 ± 12 to 92 ± 11; symptoms from 66 ± 13 to 91 ± 13; activity of daily living (ADL) from 60 ± 19 to 90 ± 21; sport from 23 ± 20 to 75 ± 20; finally, quality of life (QoL) increased from 27 ± 14 to 77 ± 19. Long-term MRI MOCART score was 64.

CONCLUSIONS

This study shows continued significant clinical improvement and good magnetic resonance imaging (MRI) findings with a minimum 5 years follow-up after implantation of a novel aragonite derived scaffold for the treatment of cartilage lesions of the knee. One patient failed and was revised with a custom-made metal implant (Episealer).

Isolated Osteochondral Autograft Versus Allograft Transplantation for the Treatment of Symptomatic Cartilage Lesions of the Knee: A Systematic Review and Meta-analysis

BACKGROUND

Focal cartilage lesions of the knee remain a difficult entity to treat. Current treatment options include arthroscopic debridement, microfracture, autograft or allograft osteochondral transplantation, and cell-based therapies such as autologous chondrocyte transplantation. Osteochondral transplantation techniques restore the normal topography of the condyles and provide mature hyaline cartilage in a single-stage procedure. However, clinical outcomes comparing autograft versus allograft techniques are scarce.

PURPOSE

To perform a comprehensive systematic review and meta-analysis of high-quality studies to evaluate the results of osteochondral autograft and allograft transplantation for the treatment of symptomatic cartilage defects of the knee.

STUDY DESIGN

Systematic review and meta-analysis; Level of evidence, 2.

METHODS

A comprehensive search of the literature was conducted using various databases. Inclusion criteria were level 1 or 2 original studies, studies with patients reporting knee cartilage injuries and chondral defects, mean follow-up ≥2 years, and studies focusing on osteochondral transplant techniques. Exclusion criteria were studies with nonknee chondral defects, studies reporting clinical outcomes of osteochondral autograft or allograft combined with other procedures, animal studies, cadaveric studies, non-English language studies, case reports, and reviews or editorials. Primary outcomes included patient-reported outcomes and failure rates associated with both techniques, and factors such as lesion size, age, sex, and the number of plugs transplanted were assessed. Metaregression using a mixed-effects model was utilized for meta-analyses.

RESULTS

The search resulted in 20 included studies with 364 cases of osteochondral autograft and 272 cases of osteochondral allograft. Mean postoperative survival was 88.2% in the osteochondral autograft cohort as compared with 87.2% in the osteochondral allograft cohort at 5.4 and 5.2 years, respectively (P = .6605). Patient-reported outcomes improved by an average of 65.1% and 81.1% after osteochondral autograft and allograft, respectively (P = .0001). However, meta-analysis revealed no significant difference in patient-reported outcome percentage change between osteochondral autograft and allograft (P = .97) and a coefficient of 0.033 (95% CI, -1.91 to 1.98). Meta-analysis of the relative risk of graft failure after osteochondral autograft versus allograft showed no significant differences (P = .66) and a coefficient of 0.114 (95% CI, -0.46 to 0.69). Furthermore, the regression did not find other predictors (mean age, percentage of female patients, lesion size, number of plugs/grafts used, and treatment location) that may have significantly affected patient-reported outcome percentage change or postoperative failure between osteochondral autograft versus allograft.

CONCLUSION

Osteochondral autograft and allograft result in favorable patient-reported outcomes and graft survival rates at medium-term follow-up. While predictors for outcomes such as mean age, percentage of female patients, lesion size, number of plugs/grafts used, and treatment location did not affect the comparison of the 2 cohorts, proper patient selection for either procedure remains paramount to the success and potentially long-term viability of the graft.

Early Postoperative CT Scan Provides Prognostic Data on Clinical Outcomes of Fresh Osteochondral Transplantation of the Knee

BACKGROUND

There is a lack of information regarding the ability of imaging studies to predict clinical outcomes after fresh osteochondral allograft (FOCA) transplantation of the knee.

PURPOSE

To determine the value of computed tomography (CT) scans to predict the clinical outcome of FOCA transplantation using the assessment computed tomography osteochondral allograft (ACTOCA) score.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

We prospectively collected data from all consecutive patients who underwent FOCA transplantation for osteochondral knee lesions at one institution between August 2017 and August 2019. All patients were followed up for a minimum of 2 years. CT scans performed 6 months after surgery were evaluated by a musculoskeletal radiologist using the ACTOCA scoring system. The radiologist was blinded to the patient's medical history. Clinical outcomes were assessed preoperatively and at 12 and 30 months postoperatively using the International Knee Documentation Committee (IKDC) score, the Kujala score, the Tegner activity scale, and the Western Ontario Meniscal Evaluation Tool (WOMET) score.

RESULTS

A total of 38 cases were included. The ACTOCA score at 6 months after surgery showed a statistically significant correlation with clinical results at 12 and 30 months. The correlation was better at 30 months, showing a high negative correlation with the IKDC score (-0.663) and a moderate negative correlation with the Kujala, WOMET, and Tegner scores (-0.593; -0.547, and -0.593, respectively) (P < .001).

CONCLUSION

A statistically significant correlation between the mean ACTOCA score on CT scans at 6 months and the clinical results measured by the IKDC, Kujala, WOMET, and Tegner scores at 30 months confirmed the predictive value of the ACTOCA score for use in clinical practice.

Evaluation of the permeation kinetics of formamide in porcine articular cartilage

Cryopreservation of articular cartilage will increase tissue availability for osteochondral allografting and improve clinical outcomes. However, successful cryopreservation of articular cartilage requires the precise determination of cryoprotectant permeation kinetics to develop effective vitrification protocols. To date, permeation kinetics of the cryoprotectant formamide in articular cartilage have not been sufficiently explored. The objective of this study was to determine the permeation kinetics of formamide into porcine articular cartilage for application in vitrification. The permeation of dimethyl sulfoxide was first measured to validate existing methods from our previously published literature. Osteochondral dowels from dissected porcine femoral condyles were incubated in 6.5 M dimethyl sulfoxide for a designated treatment time (1 s, 1 min, 2 min, 5 min, 10 min, 15 min, 30 min, 60 min, 120 min, 180 min, 24 h) at 22 °C (N = 3). Methods were then repeated with 6.5 M formamide at one of three temperatures: 4 °C, 22 °C, 37 °C (N = 3). Following incubation, cryoprotectant efflux into a wash solution occurred, and osmolality was measured from each equilibrated wash solution. Concentrations of effluxed cryoprotectant were calculated and diffusion coefficients were determined using an analytical solution to Fick's law for axial and radial diffusion in combination with a least squares approach. The activation energy of formamide was determined from the Arrhenius equation. The diffusion coefficient (2.7-3.3 × 10^-10 m²/s depending on temperature) and activation energy (0.9±0.6 kcal/mol) for formamide permeation in porcine articular cartilage were established. The determined permeation kinetics of formamide will facilitate its precise use in future articular cartilage vitrification protocols.

Computerized tomography scan evaluation after fresh osteochondral allograft transplantation of the knee correlates with clinical outcomes

Purpose

To determine the correlation between the assessment computed tomography osteochondral allograft (ACTOCA) scoring system and clinical outcomes scores. The hypothesis was that the ACTOCA score would show sufficient correlation to support its use in clinical practice.

Methods

We prospectively collected data from all consecutive patients who underwent cartilage restitution with fresh osteochondral allograft (FOCA) transplantation for osteochondral lesions of the knee and had a minimum follow-up of two years. CT scans were performed at three, six and 24 months post-operatively. A musculoskeletal radiologist blinded to the patients’ medical history evaluated the scans using the ACTOCA scoring system. Clinical outcomes collected preoperatively and at three, six and 24 months postoperatively were evaluated using the International Knee Documentation Committee (IKDC), Kujala, the Western Ontario Meniscal Evaluation Tool (WOMET), and the Tegner Activity Scale.

Results

The mean total ACTOCA score showed a statistically significant correlation with the clinical outcome. The correlation was optimal at 24 months. We found a high negative correlation with the IKDC, Kujala and Tegner (− 0.737; − 0.757, and − 0.781 respectively), and a moderate negative correlation with WOMET (− 0.566) (p < 0.001). IKDC, Kujala, WOMET, and Tegner scores showed a significant continuous improvement in all scores (p < 0.001).

Conclusion

The mean total ACTOCA score showed a linear correlation with clinical results in IKDC, Kujala, WOMET, and Tegner scores, being the highest at 24 months post-surgery. This finding supports the use of ACTOCA to standardize CT scan reports following fresh osteochondral allograft transplantation in the knee.

Quality and Variability of Physical Therapy Protocols Varies Widely for Osteochondral Allograft Transplantation of the Femoral Condyles

OBJECTIVE

To assess the quality and variability of osteochondral allograft (OCA) transplantation rehabilitation protocols associated with academic orthopedic programs in the United States.

DESIGN

A systematic review was performed to collect all publicly available online rehabilitation protocols for femoral condyle OCA transplant from US academic orthopedic programs participating in the Electronic Residency Application Service. These protocols were evaluated for inclusion of different rehabilitation components as well as timing of suggested initiation of these activities.

RESULTS

A total of 22 protocols were included. Although 91% of protocols recommended bracing, wide variation exists in total time of utilization. Median time for full weight bearing (FWB) was 7 weeks (range 4-8). On average, each protocol mentioned 9 (range 2-18) different strengthening exercises. The median time suggested to return to high-impact activities was 9 months (range 8-12). Only 3 protocols (14%) offered criteria of advancement for each phase as well as criteria for discharge.

CONCLUSION

Very few of the academic orthopedic programs have published online rehabilitation protocols following OCA transplantation. Although there is wide variation between the protocols, it allowed the identification of trends or patterns that are more common. However, there is need for more standardized evidence-based rehabilitation protocols which are easy to understand and follow by patients.

Modernizing Storage Conditions for Fresh Osteochondral Allografts by Optimizing Viability at Physiologic Temperatures and Conditions

Objective. Osteochondral allograft (OCA) transplantation has demonstrated good long-term outcomes in treatment of cartilage defects. Viability, a key factor in clinical success, decreases with peri-implantation storage at 4°C during pathogen testing, matching logistics, and transportation. Modern, physiologic storage conditions may improve viability and enhance outcomes. Design. Osteochondral specimens from total knee arthroplasty patients (6 males, 5 females, age 56.4 ± 2.2 years) were stored in media and incubated at normoxia (21% O₂) at 22°C or 37°C, and hypoxia (2% O₂) at 37°C. Histology, live-dead staining, and quantitative polymerase chain reaction (qPCR) was performed 24 hours after harvest and following 7 days of incubation. Tissue architecture, cell viability, and gene expression were analyzed. Results. No significant viability or gene expression deterioration of cartilage was observed 1-week postincubation at 37°C, with or without hypoxia. Baseline viable cell density (VCD) was 94.0% ± 2.7% at day 1. At day 7, VCD was 95.1% (37°C) with normoxic storage and 92.2% (37°C) with hypoxic storage (P ≥ 0.27). Day 7 VCD (22°C) incubation was significantly lower than both the baseline and 37°C storage values (65.6%; P < 0.01). COL1A1, COL1A2, and ACAN qPCR expression was unchanged from baseline (P < 0.05) for all storage conditions at day 7, while CD163 expression, indicative of inflammatory macrophages and monocytes, was significantly lower in the 37°C groups (P < 0.01). Conclusion. Physiologic storage at 37°C demonstrates improved chondrocyte viability and metabolism, and maintained collagen expression compared with storage at 22°C. These novel findings guide development of a method to optimize short-term fresh OCA storage, which may lead to improved clinical results.

Outcomes of Bulk Fresh Osteochondral Allografts for Cartilage Restoration in the Knee

BACKGROUND

Symptomatic osteochondral defects of the knee in young patients can cause substantial disability and predispose to osteoarthritis. Fresh osteochondral allografts (FOCAs) are a treatment option for such defects. With our institution having one of the longest-running FOCA programs, we investigated the long-term outcomes of bulk FOCA in the knee, focusing on graft survivorship, function, complications, and reoperation.

METHODS

A total of 244 patients underwent bulk FOCA in the knee from 1972 to 2018, with a mean age of 37.8 years (range, 10 to 75 years) and a mean follow-up of 9.0 years (range, 1.0 to 29.8 years). Cartilage defects were very large and uncontained, such that they were not amenable to plug transplantation. Survivorship according to Kaplan-Meier analysis was the primary outcome, and failure was defined as conversion to total knee arthroplasty, repeat allograft, graft removal, knee arthrodesis, or amputation. Functional outcome was evaluated with use of the modified Hospital for Special Surgery (mHSS) score, and radiographic evidence of osteoarthritis was classified with use of the Kellgren-Lawrence grading scale.

RESULTS

Graft survivorship was 86.6% at 5 years, 73.3% at 10 years, 58.1% at 15 years, 43.7% at 20 years, 31.9% at 25 years, and 22.6% at 30 years. The most common complications were pain (14.8%), malalignment (13.9%), and stiffness (5.8%). A total of 93 grafts (38.1%) failed at a mean of 11.0 years (range, 0.5 to 34.0 years). The mean mHSS score improved significantly, from 68.7 (range, 19 to 91) preoperatively to 80.3 (range, 52 to 100) at the time of the latest follow-up (p < 0.001). Preoperative mHSS score had a negative correlation with Kellgren-Lawrence grade at the time of the latest follow-up. Multivariate analysis revealed that graft location (i.e., medial-sided or multiple grafts) and increased age were significantly negatively associated with survival. Ten-year survival was >80% in patients below 50 years old, but <40% in patients >60 years old.

CONCLUSIONS

Bulk FOCA provided promising long-term graft survival and functional improvement in patients <50 years old. It can delay or prevent the need for total knee arthroplasty in young patients. Older patients and patients with a medial-sided graft, or multiple grafts within the same knee, had a less favorable prognosis.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Harvest, Transport, and Storage of Fresh Humeral Head Osteochondral Allograft: Step-by-Step Protocol

Articular cartilage defects are not common in the glenohumeral joint and are mostly found in patients after shoulder trauma, in patients with recurrent instability, or in patients who underwent previous surgical treatment. Articular cartilage defects lead to pain and loss of motion, consequently causing shoulder function impairment and reducing quality of life. In young patients, the use of osteochondral allografts for the treatment of humeral head defects may avoid well-known complications of shoulder arthroplasty. The goal of this Technical Note is to describe a step-by-step protocol for the harvesting, transport, and preservation of fresh humeral head osteochondral tissue for use in allograft transplantation.

Chondral Lesions of the Knee: An Evidence-Based Approach

➤

Management of chondral lesions of the knee is challenging and requires assessment of several factors including the size and location of the lesion, limb alignment and rotation, and the physical and mental health of the individual patient.

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There are a multitude of options to address chondral pathologies of the knee that allow individualized treatment for the specific needs and demands of the patient.

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Osteochondral autograft transfer remains a durable and predictable graft option in smaller lesions (<2 cm2) in the young and active patient population.

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Both mid-term and long-term results for large chondral lesions (≥3 cm2) of the knee have demonstrated favorable results with the use of osteochondral allograft or matrix-associated chondrocyte implantation.

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Treatment options for small lesions (<2 cm2) include osteochondral autograft transfer and marrow stimulation and/or microfracture with biologic adjunct, while larger lesions (≥2 cm2) are typically treated with osteochondral allograft transplantation, particulated juvenile articular cartilage, or matrix-associated chondrocyte implantation.

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Emerging technologies, such as allograft scaffolds and cryopreserved allograft, are being explored for different graft sources to address complex knee chondral pathology; however, further study is needed.

Nondestructive Assessment of Articular Cartilage Electromechanical Properties after Osteochondral Autologous and Allogeneic Transplantation in a Goat Model

OBJECTIVE

To determine the applicability of a minimally invasive diagnostic device to evaluate the quality of articular cartilage following autologous (OAT) and allogeneic (OCA) osteochondral graft transplantation in goat model.

DESIGN

OAT grafts were harvested from lateral femoral condyles (LFCs) and transplanted into osteochondral defects created in medial femoral condyles (MFCs) of contralateral knees. OCA grafts were transplanted into MFC condyles after in vitro storage. Autologous platelet-rich plasma (PRP) was administered intraarticularly after the surgery and at 1 and 2 months postoperatively. OAT and OCA grafts were evaluated macroscopically (Oswestry arthroscopy score [OAS]), electromechanically (quantitative parameter, QP), and histologically (O'Driscoll score, safranin O staining intensity) at 3 and 6 months after transplantation. Results were compared with preoperative graft evaluation.

RESULTS

Transplanted cartilage deteriorated within 6 months in all groups. Cartilage quality was better retained in OAT group compared with a decline in OCA group. QP and OAS scores were comparable in OAT and OCA groups at 3 months, but superior in OAT group at 6 months, according to all the methods applied. PRP injections significantly improved QP and OAS score at 6 months compared with 3 months in OAT group. QP moderately correlated with OAS, O'Driscoll score, and safranin O staining intensity.

CONCLUSIONS

Grafts did not retain preoperative quality parameters at 6 months follow-up; however, OAT were superior to OCA grafts. PRP may have a beneficial effect on macroscopic and electromechanical properties of cartilage; however, histological improvement is yet to be proved. Electromechanical diagnostic device enables reliable assessment of transplanted cartilage.

Patient-Reported Outcomes After Structural Autograft for Large or Cystic Talar Dome Osteochondral Lesions

BACKGROUND

While smaller talar dome osteochondral lesions (OCLs) are successfully treated with bone marrow stimulation techniques, the optimal treatment for large or cystic OCLs remains controversial. This study tested the hypothesis that transferring structural autograft bone from the distal tibia to the talus for large or cystic OCLs improves pain and function.

METHODS

Thirty-two patients with large or cystic OCLs underwent structural bone grafting from the ipsilateral distal tibia to the talar dome. Patients were assessed with subjective patient-centered tools and objective clinical outcomes. Average age was 48.6 ± 14.9 years, and average follow-up was 19.5 ± 13.3 months. Average lesion area was 86.2 ± 23.5 mm², and average depth was 8.4 ± 3.0mm.

RESULTS

At final follow-up, improvement compared to preoperative scores was seen in American Orthopaedic Foot & Ankle Society (65.4 ± 21.2 to 86.9 ± 15.0, P < .05), Foot Function Index (48.9 ± 20.8 to 21.1 ± 18.9, P < .05), visual analog scale for pain (4.7 ± 3.0 to 1.4 ± 1.5, P < .05), and Patient-Reported Outcomes Measurement Information System (PROMIS) Physical Function (40.4 ± 5.4 to 45.5 ± 7.4, P < .05) scores. There was no improvement in PROMIS pain interference (54.7 ± 18.1 to 52.4 ± 7.3, P > .05). Satisfaction with surgery was 8.4 ± 1.3/10, and 96% of patients would have the procedure again. Ninety-four percent of patients returned to work and/or play. One patient had a deep vein thrombosis 6 weeks postoperatively, and 1 patient underwent ankle fusion at 18 months postoperatively.

CONCLUSION

This study demonstrates that structural bone graft harvested from the distal tibia transferred to the talus was a safe and effective treatment for large and cystic OCLs. Outcomes compare favorably to other described techniques for treatment of these injuries.

LEVEL OF EVIDENCE

Level IV, case series.

Protocol for Harvest, Transport and Storage of Human Osteochondral Tissue

Objective  To elaborate a protocol for the harvest, transport, and preservation of human osteochondral tissue for use in tissue banks (TBs).

Methods  Osteochondral fragments measuring 2 cm ³ of 5 corpse donors aged between 15 and 45 years old were analyzed. The samples were stored in cell preservation medium containing: human albumin, Iscove's and vancomycin preserved at 4°C. The concentration of proteoglycans in the extracellular medium was quantified by the use of Safranin-O, while tissue structural analysis was assessed by histological study with hematoxylin-eosin stained slides. The images obtained were analyzed according to the histological scores of Mankin and the score proposed by the OsteoArthritis Research Society International. The samples were analyzed with 0, 15, 30 and 45 days of preservation.

Results  The osteochondral fragments studied showed a progressive decrease in proteoglycan concentration with increased preservation time. After 30 days of preservation, structural changes were identified with discontinuity of the cartilage surface layer. According to the results obtained by the Mankin score, there was a statistically significant difference between 15 and 30 days of tissue preservation.

Conclusion  The protocol described defined knee transport immersed in Lactated Ringer at a controlled temperature of 10° C until its arrival at the TB. After processing, the preservation solution was composed of Iscove's serum-free cell culture medium supplemented with 10% human albumin and 100 μg/ml vancomycin. The tissue was preserved at a temperature of 4°C until the moment of transplantation characterizing the fresh preservation.

Using engineering models to shorten cryoprotectant loading time for the vitrification of articular cartilage

Osteochondral allograft transplantation can treat full thickness cartilage and bone lesions in the knee and other joints, but the lack of widespread articular cartilage banking limits the quantity of cartilage available for size and contour matching. To address the limited availability of cartilage, vitrification can be used to store harvested joint tissues indefinitely. Our group's reported vitrification protocol [Biomaterials 33 (2012) 6061-6068] takes 9.5 h to load cryoprotectants into intact articular cartilage on bone and achieves high cell viability, but further optimization is needed to shorten this protocol for clinical use. Herein, we use engineering models to calculate the spatial and temporal distributions of cryoprotectant concentration, solution vitrifiability, and freezing point for each step of the 9.5-h protocol. We then incorporate the following major design choices for developing a new shorter protocol: (i) all cryoprotectant loading solution concentrations are reduced, (ii) glycerol is removed as a cryoprotectant, and (iii) an equilibration step is introduced to flatten the final cryoprotectant concentration profiles. We also use a new criterion-the spatially and temporally resolved prediction of solution vitrifiability-to assess whether a protocol will be successful instead of requiring that each cryoprotectant individually reaches a certain concentration. A total cryoprotectant loading time of 7 h is targeted, and our new 7-h protocol is predicted to achieve a level of vitrifiability comparable to the proven 9.5-h protocol throughout the cartilage thickness.

Fresh Osteochondral Resurfacing of the Patellofemoral Joint

Large osteochondral lesions of the knee in young patients continue to be a challenge for orthopaedic surgeons and the focus of continual research. This is particularly true if the injury is a consequence of a dysplastic trochlea and involves both articular surfaces of the biomechanically complex patellofemoral joint. To obtain a healthy and congruent patellofemoral joint, the use of a bipolar fresh osteochondral allograft transplantation of the patella and trochlea is one of the few options to biologically treat these injuries. This would achieve a replacement of the entire articular surface of the patellofemoral joint with a high number of viable chondrocytes and respect the unique structural characteristics of the cartilage. The aim of this study was to obtain symptomatic and functional improvements while delaying the timing of prosthetic surgery. We present a reproducible although demanding surgical technique to perform a bipolar fresh osteochondral allograft transplantation of the patella and trochlea.

Fluorescent Nanodiamonds Enable Long-Term Detection of Human Adipose-Derived Stem/Stromal Cells in an In Vivo Chondrogenesis Model Using Decellularized Extracellular Matrices and Fibrin Glue Polymer

Clinically available materials, including allogeneic irradiated costal cartilage and fibrin glue polymer, were used as scaffolds for in vivo chondrogenic differentiation of human adipose-derived stem/stromal cells (hASCs) in the attempt to develop a more efficient treatment over current methods. Current studies include the use of growth-factor stimulation, tissue engineering, and biocompatible materials; however, most methods involve complicated processes and pose clinical limitations. In this report, the xenografts in the experimental group composed of a diced decellularized cartilage extracellular matrix (ECM), hASCs, and fibrin glue polymer were implanted into the subcutaneous layer of nude mice, and the results were compared with two groups of controls; one control group received implantation of decellularized cartilage ECM and fibrin glue polymer, and the other control group received implantation of hASCs mixed with fibrin glue polymer. To evaluate whether hASCs had in vivo chondrogenesis in the xenografts, hASCs were labeled with fluorescent nanodiamonds (FNDs), a biocompatible and photostable nanomaterial, to allow for long-term detection and histological analysis. Increased cellularity, glycosaminoglycan, and collagen deposition were found by the histological examination in the experimental group compared with control groups. With the background-free detection technique and time-gated fluorescence imaging, the numbers and locations of the FND-labeled hASCs could be detected by confocal microscopy. The chondrocyte-specific markers, such as aggrecan and type II collagen, were colocalized with cells containing signals of FNDs which indicated in vivo chondrogenesis of hASCs. Taken together, functional in vivo chondrogenesis of the hASCs could be achieved by clinically available decellularized cartilage ECM and fibrin glue polymer in the nude mice model without in vitro chondrogenic induction. The fluorescent signals of FNDs in hASCs can be detected in histological analysis, such as hematoxylin and eosin staining (H&E staining) without the interference of the autofluorescence. Our study may warrant future clinical applications of the combination of decellular cartilage ECM, fibrin glue polymer, and hASCs for cartilage repair.

Beyond Cartilage Repair: The Role of the Osteochondral Unit in Joint Health and Disease

Once believed to be limited to articular cartilage, osteoarthritis is now considered to be an organ disease of the “whole joint.” Damage to the articular surface can lead to, be caused by, or occur in parallel with, damage to other tissues in the joint. The relationship between cartilage and the underlying subchondral bone has particular importance when assessing joint health and determining treatment strategies. The articular cartilage is anchored to the subchondral bone through an interface of calcified cartilage, which as a whole makes up the osteochondral unit. This unit functions primarily by transferring load-bearing weight over the joint to allow for normal joint articulation and movement. Unfortunately, irreversible damage and degeneration of the osteochondral unit can severely limit joint function. Our understanding of joint pain, the primary complaint of patients, is poorly understood and past efforts toward structural cartilage restoration have often not been associated with a reduction in pain. Continued research focusing on the contribution of subchondral bone and restoration of the entire osteochondral unit are therefore needed, with the hope that this will lead to curative, and not merely palliative, treatment options. The purpose of this narrative review is to investigate the role of the osteochondral unit in joint health and disease. Topics of discussion include the crosstalk between cartilage and bone, the efficacy of diagnostic procedures, the origins of joint pain, current and emerging treatment paradigms, and suitable preclinical animal models for safety and efficacy assessment of novel osteochondral therapies. The goal of the review is to facilitate an appreciation of the important role played by the subchondral bone in joint pain and why the osteochondral unit as a whole should be considered in many cases of joint restoration strategies.

Effect of Autogenous Bone Marrow Aspirate Treatment on Magnetic Resonance Imaging Integration of Osteochondral Allografts in the Knee: A Matched Comparative Imaging Analysis

PURPOSE

To accurately evaluate the effects of bone marrow aspirate (BMA) augmentation on osteochondral allograft (OCA) integration on early postoperative magnetic resonance imaging (MRI) using the comprehensive Osteochondral Allograft MRI Scoring System (OCAMRISS).

METHODS

This imaging study compared patients who underwent OCA transplantation with and without BMA augmentation for the treatment of focal osteochondral defects in the knee performed by a single surgeon between July 2013 and July 2017. Patients were excluded if they underwent implantation of premade plugs, had an overlapping OCA configuration ("snowman" technique), or did not undergo MRI at 6 months postoperatively. Patients were matched by lesion location, lesion size, age, and body mass index, as well as whether they underwent previous surgical procedures. Data were analyzed using descriptive statistics, Spearman correlation, the independent t test, the Mann-Whitney U test, and the χ² test.

RESULTS

A total of 58 patients (29 per group) were included in this study, with an average age of 36.4 ± 10.1 years and mean body mass index of 28.6 ± 5.1. The mean size of the analyzed OCA plugs was 3.3 ± 1 cm². At an average imaging follow-up of 5.6 ± 1 months, 86.2% of the grafts had achieved osseous integration at the graft-host junction and 75.9% did not show any cystic changes in the subchondral bone. No difference in any OCAMRISS subscale was seen comparing OCAs with and without BMA augmentation (P > .05). Specifically, osseous integration and subchondral cyst formation were comparable between groups (P = .128 and P = .539, respectively).

CONCLUSIONS

OCAs showed excellent osseous integration at the graft-host junction on 6-month postoperative MRI. The treatment of OCAs with autogenous BMA did not result in superior imaging outcomes when analyzed using the OCAMRISS.

LEVEL OF EVIDENCE

Level III, case-control study.

Decreased Graft Thickness Is Associated With Subchondral Cyst Formation After Osteochondral Allograft Transplantation in the Knee

BACKGROUND

Subchondral changes, specifically cyst formation, are a known finding after osteochondral allograft (OCA) transplantation.

PURPOSE/HYPOTHESIS

The purpose was to determine potential predictive associations between preoperative patient characteristics or OCA morphology and postoperative OCA appearance as assessed by the osteochondral allograft magnetic resonance imaging scoring system (OCAMRISS) at 6-month follow-up. It was hypothesized that preoperative patient factors or OCA morphology is associated with postoperative OCAMRISS scores.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

This study evaluated 74 OCAs that were implanted in the femoral condyles of 63 patients for the treatment of symptomatic osteochondral defects in the knee. Postoperative magnetic resonance imaging was obtained at a mean ± SD follow-up of 5.5 ± 1.0 months. A musculoskeletal radiologist scored all grafts according to the OCAMRISS. Point biserial correlation, Mann-Whitney U test, Fisher exact test, and chi-square test were used to distinguish associations between OCAMRISS subscales and age, sex, smoker status, body mass index, previous surgery, concomitant surgery, bone marrow augmentation, graft location, graft size, and bony graft thickness.

RESULTS

OCA bony thickness showed significant correlation with cystic changes at the graft-host junction (P = .019). Grafts with cystic formation were significantly thinner than grafts without cystic changes (P = .008). The odds ratio for grafts with <5-mm bony thickness demonstrating cystic changes was 4.9 (95% CI, 1.5-16.1; P = .009). Bony graft thickness was not associated with graft integration, but 40% of grafts with a bony thickness >9 mm presented with a residual osseous cleft, as opposed to 11.3% of thinner grafts (P = .1). The augmentation with bone marrow aspirate did not affect osseous graft integration or subchondral cystic formation (P = .375 and P = .458, respectively).

CONCLUSION

Osteochondral allograft thickness is associated with subchondral cyst formation at short-term follow-up. Thin grafts demonstrate a substantially increased risk of developing subchondral cysts at the graft-host junction after OCA transplantation. Conversely, thicker grafts may negatively affect osseous graft integration. Hence, surgeons should be aware of the potential pitfalls of transplanting thin or thick grafts regarding cystic formation and delay of osseous integration after cartilage resurfacing.

The cost-effectiveness of osteochondral allograft transplantation in the knee

PURPOSE

Osteochondral allografts (OCA) consist of a layer of hyaline cartilage and a layer of underlying bone. They are used to repair combined defects of articular cartilage and bone. Such defects often occur in people far too young to have knee arthroplasty, for whom the main alternative to OCA is conservative symptomatic care, which will not prevent development of osteoarthritis. The aim of this report was to assess the cost-effectiveness of osteochondral allograft transplantation in the knee.

METHODS

Systematic review of evidence on clinical effectiveness and economic modelling.

RESULTS

The evidence on osteochondral allograft transplantation comes from observational studies, but often based on good quality prospective registries of all patients having such surgery. Without controlled trials, it was necessary to use historical cohorts to assess the effect of osteochondral grafts. There is good evidence that OCA are clinically effective with a high graft survival rate over 20 years. If an OCA graft fails, there is some evidence that revision with a second OCA is also effective, though less so than primary OCA. Economic modelling showed that osteochondral allograft transplantation was highly cost-effective, with costs per quality adjusted life year much lower than many other treatments considered cost effective.

CONCLUSIONS

Osteochondral allograft transplantation appears highly cost-effective though the cost per quality adjusted life year varies according to the widely varying costs of allografts. Based on one small study, revision OCA also appears very cost-effective, but more evidence is needed.

LEVEL OF EVIDENCE

II.

Failure After Osteochondral Allograft Transplantation with the Chondrofix Implant: A Report of Two Cases

CASE

This report describes 2 cases of failed decellularized "off-the-shelf" Chondrofix (Zimmer Biomet) osteochondral allografts within a year after implantation in a 44-year-old man and a 50-year-old woman.

CONCLUSION

Although it is a successful technique for cartilage repair, the use of osteochondral allograft transplantation has been limited by the availability of fresh grafts; therefore, decellularized osteochondral allografts recently have been developed. Physicians should be cautious when considering the use of these implants for the repair of articular cartilage lesions.

Graft-Recipient Anteroposterior Mismatch Does Not Affect the Midterm Clinical Outcomes of Osteochondral Allograft Transplantation of the Femoral Condyle

BACKGROUND

For the treatment of femoral condyle cartilage defects with osteochondral allograft transplantation (OCA), many surgeons have relaxed their graft-recipient size-matching criteria given the limited allograft supply. However, since the anteroposterior (AP) length is typically correlated with the radius of curvature for a given condyle, a large mismatch in graft-recipient AP length can indicate a corresponding mismatch in the radius of curvature, leading to articular incongruity after implantation.

PURPOSE

To evaluate the association between femoral condyle graft-recipient AP mismatch and clinical outcomes of OCA.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A retrospective review was conducted of patients treated with OCA for femoral condyle chondral defects from 2000 to 2015. Graft characteristics, including AP and mediolateral dimensions, were gathered from vendor-specific allograft offering documents. Patient condyle dimensions were measured on preoperative magnetic resonance imaging. Reoperations and patient responses to validated outcome measures were reviewed. Failure was defined by any partial removal/revision of the allograft or conversion to knee arthroplasty. A multivariable logistic regression model was fitted to examine the association of AP mismatch with OCA failure while adjusting for patient age and number of previous ipsilateral knee surgical procedures.

RESULTS

A total of 69 knees from 69 patients (mean age, 35.7 years; 71% male) met the inclusion criteria. Mean duration of follow-up was 4 years (range, 2-16 years). The mean absolute graft-recipient AP mismatch was 6.7 mm (range, 0-20 mm; P < .01). At final follow-up, 19 knees had failed. There was no significant difference in the mean absolute AP mismatch between failures (8.1 mm) and nonfailures (6.2 mm; P = .17). Multivariate logistic regression revealed that AP mismatch was not associated with graft failure ( P = .14). At final follow-up, significant improvements were noted in the 36-Item Short Form Health Survey, International Knee Documentation Committee subjective form, and Knee Outcome Survey-Activities of Daily Living ( P < .01 for all). Magnitude of AP mismatch was not associated with postoperative outcome scores or achievement of minimal clinically significant differences in outcome scores.

CONCLUSION

Magnitude of graft-recipient AP mismatch was not associated with midterm OCA failure rates or patient-reported outcome scores, suggesting that AP length mismatch within the limits measured here is not a contraindication for graft acceptance.

Effects of Proud Large Osteochondral Plugs on Contact Forces and Knee Kinematics: A Robotic Study

BACKGROUND

Osteochondral allograft (OCA) transplantation is used to treat large focal femoral condylar articular cartilage defects. A proud plug could affect graft survival by altering contact forces (CFs) and knee kinematics.

HYPOTHESIS

A proud OCA plug will significantly increase CF and significantly alter knee kinematics throughout controlled knee flexion.

STUDY DESIGN

Controlled laboratory study.

METHODS

Human cadaver knees had miniature load cells, each with a 20-mm-diameter cylinder of native bone/cartilage attached at its exact anatomic position, installed in both femoral condyles at standardized locations representative of clinical defects. Spacers were inserted to create proud plug conditions of +0.5, +1.0, and +1.5 mm. CFs and knee kinematics were recorded as a robot flexed the knee continuously from 0° to 50° under 1000 N of tibiofemoral compression.

RESULTS

CFs were increased significantly (vs flush) for all proudness conditions between 0° and 45° of flexion (medial) and 0° to 50° of flexion (lateral). At 20°, the average increases in medial CF for +0.5-mm, +1-mm, and +1.5-mm proudness were +80 N (+36%), +155 N (+70%), and +193 N (+87%), respectively. Corresponding increases with proud lateral plugs were +44 N (+14%), +90 N (+29%), and +118 N (+38%). CF increases for medial plugs at 20° of flexion were significantly greater than those for lateral plugs at all proudness conditions. At 50°, a 1-mm proud lateral plug significantly decreased internal tibial rotation by 15.4° and decreased valgus rotation by 2.5°.

CONCLUSION

A proud medial or lateral plug significantly increased CF between 0° and 45° of flexion. Our results suggest that a medial plug at 20° may be more sensitive to graft incongruity than a lateral plug. The changes in rotational kinematics with proud lateral plugs were attributed to earlier contact between the proud plug's surface and the lateral meniscus, leading to rim impingement with decreased tibial rotation.

CLINICAL RELEVANCE

Increased CF and altered knee kinematics from a proud femoral plug could affect graft viability. Plug proudness of only 0.5 mm produced significant changes in CF and knee kinematics, and the clinically accepted 1-mm tolerance may need to be reexamined in view of our findings.

Orthopedic Surgical Options for Joint Cartilage Repair and Restoration

The limited natural capacity for articular cartilage to regenerate has led to a continuously broadening array of surgical interventions. Used once patients' symptoms are not relieved by nonoperative management, these share the goals of joint preservation and restoration. Techniques include bone marrow stimulation, whole-tissue transplantation, and cell-based strategies, each with its own variations. Many of these interventions are performed arthroscopically or with extended-portal techniques. Indications, operative techniques, unique benefits, and limitations are presented.

Fresh Osteochondral Patellar Allograft Resurfacing

The treatment of articular cartilage lesions in young patients is certainly a complex matter and subject of continuous research, particularly for those located at the patellofemoral joint, given its peculiar biomechanical characteristics. Osteochondral grafts can be of relatively small size when the defect is focal and in an area that allows good stability and consequently the graft's integration. In case of large or multifocal lesions, it is possible to consider an osteochondral transplantation of the entire articular surface of the patella. We present a simple and reproducible technique to perform a patellar fresh osteochondral allograft resurfacing attempting to reduce the symptoms and delay a prosthetic implant in young patients with advanced patellar chondral injuries.

Large Osteochondral Allografts of the Knee: Surgical Technique and Indications

Large osteochondral allograft (OCA) transplant has become a valid alternative to restore articular surface in challenging articular lesions in young and active patients, either in primary or in revision procedures. Several studies support the effectiveness and safety of OCA, but costs and graft availability limit their use. The indications are the treatment of symptomatic full-thickness cartilage lesions greater than 3 cm ² , deep lesions with subchondral damage, or revision procedures when a previous treatment has failed. The goal of the transplant is to restore the articular surface with a biological implant, allow return to daily/sports activities, relieve symptoms, and delay knee arthroplasty. Grafts can be fresh, fresh-frozen, or cryopreserved; these different storage procedures significantly affect cell viability, immunogenicity, and duration of the storage. Dowel and shell technique are the two most commonly used procedures for OCA transplantation. While most cartilage lesions can be treated with the dowel technique, large and/or geometrically irregular lesions should be treated with the shell technique. OCA transplantation for the knee has demonstrated reliable mid- to long-term results in terms of graft survival and patient satisfaction. Best results are reported: in unipolar lesions, in patients younger than 30 years, in traumatic lesions and when the treatment is performed within 12 months from the onset of symptoms.

Long-term Clinical Outcomes After Microfracture of the Glenohumeral Joint: Average 10-Year Follow-up

BACKGROUND

Microfracture is an effective surgical treatment for full-thickness cartilage defects of the knee; however, little is known regarding long-term outcomes after microfracture in the shoulder.

PURPOSE

To present long-term clinical outcomes of patients undergoing microfracture of full-thickness articular cartilage defects of the glenohumeral joint.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Sixteen consecutive patients (17 shoulders) were retrospectively reviewed who underwent arthroscopic microfracture of the humeral head and/or glenoid surface, with or without additional procedures between 2001 and 2008 and with a minimum follow-up of 8.5 years. All patients completed pre- and postoperative surveys containing the visual analog scale, American Shoulder and Elbow Surgeons form, and Simple Shoulder Test. Complications and reoperations were analyzed. Failure was defined by biological resurfacing or conversion to arthroplasty.

RESULTS

Of the original 16 patients (17 shoulders), 13 patients (14 shoulders) were available for mean follow-up at 10.2 ± 1.8 years after microfracture (range, 8.5-15.8 years), for an overall clinical follow-up rate of 82%. The patients (6 men, 7 women) were 36.1 ± 12.9 years old at time of microfracture. The average size of humeral head defects was 5.20 cm² (range, 4.0-7.84 cm²), and the average size of glenoid defects was 1.53 cm² (range, 1.0-3.75 cm²). Four patients (4 shoulders) underwent at least 1 reoperation, and 3 were considered to have structural failures. The average time to failure was 3.7 years after microfracture (range, 0.2-9.6 years). The overall survival rate was 76.6% at 9.6 years. For these patients, there were statistically significant improvements in visual analog scale, Simple Shoulder Test, and American Shoulder and Elbow Surgeons scores as compared with preoperative values at long-term follow-up ( P < .05 for all), without any significant change from short-term (mean, 2.3 years) to long-term (mean, 10.2 years) follow-up. There was no significant difference in Single Assessment Numeric Evaluation or Short Form-12 Physical or Mental scores between short- and long-term follow-up. When compared with short-term follow-up, in which 2 patients had already failed, 1 additional patient progressed to failure at 9.6 years after the original microfracture. Two patients (2 shoulders) were considered to have clinical failure. Owing to the overall number of failures (3 structural failure and 2 clinical failure), the total long-term success rate of glenohumeral microfracture is 66.7% in the current study.

CONCLUSION

Treating full-thickness symptomatic chondral defects of the glenohumeral joint with microfracture can result in long-term improved function and reduced pain for some patients. However, in this case series, 21.4% of patients required conversion to arthroplasty <10 years after the index microfracture procedure, and 33% to 42% of patients were considered to have potential clinical failure. Additional studies with larger patient cohorts are needed.

Emerging Concepts in Treating Cartilage, Osteochondral Defects, and Osteoarthritis of the Knee and Ankle

The management and treatment of cartilage lesions, osteochondral defects, and osteoarthritis remain a challenge in orthopedics. Moreover, these entities have different behaviors in different joints, such as the knee and the ankle, which have inherent differences in function, biology, and biomechanics. There has been a huge development on the conservative treatment (new technologies including orthobiologics) as well as on the surgical approach. Some surgical development upraises from technical improvements including advanced arthroscopic techniques but also from increased knowledge arriving from basic science research and tissue engineering and regenerative medicine approaches. This work addresses the state of the art concerning basic science comparing the knee and ankle as well as current options for treatment. Furthermore, the most promising research developments promising new options for the future are discussed.

Similar Outcomes After Osteochondral Allograft Transplantation in Anterior Cruciate Ligament-Intact and -Reconstructed Knees: A Comparative Matched-Group Analysis With Minimum 2-Year Follow-Up

PURPOSE

To compare failure rates and clinical outcomes of osteochondral allograft transplantation (OCA) in anterior cruciate ligament (ACL)-intact versus ACL-reconstructed knees at midterm follow-up.

METHODS

After a priori power analysis, a prospective registry of patients treated with OCA for focal chondral lesions ≥2 cm² in size with minimum 2-year follow-up was used to match ACL-reconstructed knees with ACL-intact knees by age, sex, and primary chondral defect location. Exclusion criteria included meniscus transplantation, realignment osteotomy, or other ligamentous injury. Complications, reoperations, and patient responses to validated outcome measures were reviewed. Failure was defined by any procedure involving allograft removal/revision or conversion to arthroplasty. Kaplan-Meier analysis and multivariate Cox regression were performed to evaluate the association of ACL reconstruction (ACLR) with failure.

RESULTS

A total of 50 ACL-intact and 25 ACL-reconstructed (18 prior, 7 concomitant) OCA patients were analyzed. The mean age was 36.2 years (range, 14-62 years). Mean follow-up was 3.9 years (range, 2-14 years). Patient demographics and chondral lesion characteristics were similar between groups. ACL-reconstructed patients averaged 2.2 ± 1.9 prior surgeries on the ipsilateral knee compared with 1.4 ± 1.4 surgeries for ACL-intact patients (P = .014). Grafts used for the last ACLR included bone-patellar tendon-bone autograft, hamstring autograft, Achilles tendon allograft, and tibialis allograft (data available for only 11 of 25 patients). At final follow-up, 22% of ACL-intact and 32% of ACL-reconstructed patients had undergone reoperation. OCA survivorship was 90% and 96% at 2 years and 79% and 85% at 5 years in ACL-intact and ACL-reconstructed patients, respectively (P = .774). ACLR was not independently associated with failure. Both groups demonstrated clinically significant improvements in the Short Form-36 pain and physical functioning, International Knee Documentation Committee subjective, and Knee Outcome Survey-Activities of Daily Living scores at final follow-up (P < .001), with no significant differences in preoperative, postoperative, and change scores between groups.

CONCLUSIONS

OCA in the setting of prior or concomitant ACLR does not portend higher failure rates or compromise clinical outcomes.

LEVEL OF EVIDENCE

Level III, retrospective comparative study.

Contact Forces Acting on Large Femoral Osteochondral Allografts During Forced Knee Extension

BACKGROUND

A single cylindrical graft plug is commonly used for large focal femoral defects during osteochondral allograft (OCA) transplantation. Excessive contact force (CF) on a proud plug could compromise initial healing. CFs during forced knee extension are of particular interest because this maneuver is used by therapists to restore early postoperative range of motion.

HYPOTHESIS

A proud OCA plug will significantly increase the CF and significantly decrease the knee extension angle (KEA).

STUDY DESIGN

Controlled laboratory study.

METHODS

Eleven human knee specimens had miniature load cells installed in both femoral condyles at standardized locations representative of clinical defects. Each load cell had a 20-mm-diameter cylinder of native bone/cartilage attached at its precise anatomic location. Four spacers, 0.5 mm in thickness, were inserted sequentially between each load cell and its mounting bracket to create proud plug conditions of 0.5 to 2 mm. Measurements of the CF and KEA were recorded at extension moment levels up to 8 N·m.

RESULTS

At 8 N·m, the mean CFs for flush plugs were 149 ± 18 N (lateral) and 34 ± 13 N (medial). The mean increases in the medial CF (compared with flush) for 0.5-mm, 1-mm, 1.5-mm, and 2-mm proud conditions were 31 N (+91%), 64 N (+188%), 111 N (+325%), and 154 N (+451%), respectively. Corresponding increases for lateral proud plugs were 55 N (+37%), 120 N (+81%), 162 N (+109%), and 210 N (+141%), respectively. The CFs (and CF increases) for lateral grafts were significantly ( P < .05) higher than corresponding values for medial grafts at each proudness condition. Medial plug proudness had no consistent effect on the KEA. A 1-mm proud lateral plug significantly reduced the KEA by -1.6° (0 N·m) and -0.9° (2 N·m).

CONCLUSION

Graft proudness of only 0.5 mm significantly increased CFs during forced knee extension, emphasizing the surgical precision necessary to achieve normal CF levels.

CLINICAL RELEVANCE

It is believed that some amount of CF is beneficial in the early stages of graft healing, and our findings suggest that forced knee extension may be well suited for this purpose. However, the surgeon should be aware that large extension moments can also generate relatively high CFs, especially if the plug is proud.

Effects of Autogenous Bone Marrow Aspirate Concentrate on Radiographic Integration of Femoral Condylar Osteochondral Allografts

BACKGROUND

Transplantation of fresh osteochondral allografts (OCAs) is an attractive treatment option for symptomatic articular cartilage lesions in young, healthy patients. Because the lack of OCA bone integration can be a cause of treatment failure, methods for speeding and enhancing OCA bone integration to mitigate this potential complication are highly desirable.

PURPOSE

To determine if autogenous bone marrow aspirate concentrate (BMC) treatment of large femoral condylar OCAs would be associated with superior radiographic OCA bone integration compared with nontreated allografts during the critical first 6 months after surgery.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A review of patients enrolled in a prospective registry who were treated with transplantation of large OCAs to one or both femoral condyles at our institution from March 12, 2013 to March 14, 2016 was performed. Patients were stratified into 2 groups based on BMC treatment versus no BMC treatment; the treatment was nonrandomized and was rooted in a shift in practice and a continuing effort to optimize OCA transplantation at our institution. Patients were excluded if they did not have orthogonal view radiographs performed at 6 weeks, 3 months, and 6 months postoperatively. Each condyle undergoing OCA transplantation was assessed individually by an independent musculoskeletal radiologist, who was blinded to the treatment group and time point. OCAs were assessed with respect to graft integration (0%-100%; 0 = no integration, 100 = complete integration) and degree of sclerosis (0-3; 0 = normal, 1 = mild sclerosis, 2 = moderate sclerosis, and 3 = severe sclerosis) of the graft at each time point.

RESULTS

This study identified 17 condyles in 15 patients who underwent OCA transplantation without BMC and 29 condyles in 22 patients who underwent OCA transplantation with BMC. The BMC group had significantly ( P = .033) higher graft integration scores at 6 weeks, 3 months, and 6 months after surgery. Graft sclerosis was significantly ( P = .017) less in the BMC group at 6 weeks and 3 months, with no significant difference at 6 months after surgery. When combining the groups to examine the influence of smoking on graft integration, nonsmokers had significantly ( P = .007) higher graft integration scores at 6 months.

CONCLUSION

Large femoral condylar OCAs treated with autogenous BMC before implantation showed superior radiographic integration to bone and less sclerosis during the initial 6-month postoperative period. BMC treatment of OCAs may mitigate the failure of OCA bone healing.

History of osteochondral allograft transplantation

Osteochondral defects or injuries represent the most challenging entities to treat, especially when occur to young and active patients. For centuries, it has been recognized that such defects are almost impossible to treat. However, surgeons have never stopped the effort to develop reliable methods to restore articular cartilage and salvage the endangered joint function. Osteochondral allograft transplantation in human was first introduced by Eric Lexer in 1908. Since that era, several pioneers have been worked in the field of osteochondral allotransplantation, presenting and developing the basic research, the methodology and the surgical techniques. Herein we present in brief, the history and the early clinical results of osteochondral allograft transplantation in human.

Pathohistological investigation of osteochondral tissue obtained during total knee arthroplasty after osteochondral autologous transfer: a case report

Background

Osteochondral autologous transfer is one of the repair techniques for cartilage defects of knee with promising knee function recovery. There are no reports including histopathological images concerning human osteochondral tissue after osteochondral autologous transfer. This is the first report to present pathohistological findings of transplanted plugs and host tissues extracted from the human body 3 years after osteochondral autologous transfer. This study aimed to explore the cause factor of chronic pain using histological techniques.

Case presentation

A 67-year-old Japanese man presented with adjusted total knee arthroplasty 3 years after osteochondral autologous transfer. Although in pain, arthroscopic assessment was not severe. The specimens which was gained during total knee arthroplasty were investigated in gross and microscopically using immunohistochemical staining technic. Histological examination revealed that the gap between grafted plugs and host osteochondral tissues was filled with fibrous tissue that stained positive for type I collagen. A degenerative change and some neovascularity were observed in the regenerated tissue and host trabecular bone. Furthermore, cysts and bone marrow edema were observed.

Conclusion

Our data suggests that the host osteochondral morbidity around grafted plugs might be related to chronical pain and revision surgery.

The use of mesenchymal stem cells for cartilage repair and regeneration: a systematic review

BACKGROUND

The management of articular cartilage defects presents many clinical challenges due to its avascular, aneural and alymphatic nature. Bone marrow stimulation techniques, such as microfracture, are the most frequently used method in clinical practice however the resulting mixed fibrocartilage tissue which is inferior to native hyaline cartilage. Other methods have shown promise but are far from perfect. There is an unmet need and growing interest in regenerative medicine and tissue engineering to improve the outcome for patients requiring cartilage repair. Many published reviews on cartilage repair only list human clinical trials, underestimating the wealth of basic sciences and animal studies that are precursors to future research. We therefore set out to perform a systematic review of the literature to assess the translation of stem cell therapy to explore what research had been carried out at each of the stages of translation from bench-top (in vitro), animal (pre-clinical) and human studies (clinical) and assemble an evidence-based cascade for the responsible introduction of stem cell therapy for cartilage defects. This review was conducted in accordance to PRISMA guidelines using CINHAL, MEDLINE, EMBASE, Scopus and Web of Knowledge databases from 1st January 1900 to 30th June 2015. In total, there were 2880 studies identified of which 252 studies were included for analysis (100 articles for in vitro studies, 111 studies for animal studies; and 31 studies for human studies). There was a huge variance in cell source in pre-clinical studies both of terms of animal used, location of harvest (fat, marrow, blood or synovium) and allogeneicity. The use of scaffolds, growth factors, number of cell passages and number of cells used was hugely heterogeneous.

SHORT CONCLUSIONS

This review offers a comprehensive assessment of the evidence behind the translation of basic science to the clinical practice of cartilage repair. It has revealed a lack of connectivity between the in vitro, pre-clinical and human data and a patchwork quilt of synergistic evidence. Drivers for progress in this space are largely driven by patient demand, surgeon inquisition and a regulatory framework that is learning at the same pace as new developments take place.

Osteochondral Allograft Transplantation of the Knee: Analysis of Failures at 5 Years

BACKGROUND

Osteochondral allograft transplantation (OAT) is being performed with increasing frequency, and the need for reoperations is not uncommon.

PURPOSE

To quantify survival for OAT and report findings at reoperations.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

A review of prospectively collected data of 224 consecutive patients who underwent OAT by a single surgeon with a minimum follow-up of 2 years was conducted. The reoperation rate, timing of reoperation, procedure performed, and findings at surgery were reviewed. Failure was defined by revision OAT, conversion to knee arthroplasty, or gross appearance of graft failure at second-look arthroscopic surgery.

RESULTS

A total of 180 patients (mean [±SD] age, 32.7 ± 10.4 years; 52% male) who underwent OAT with a mean follow-up of 5.0 ± 2.7 years met the inclusion criteria (80% follow-up). Of these, 172 patients (96%) underwent a mean of 2.5 ± 1.7 prior surgical procedures on the ipsilateral knee before OAT. Forty-eight percent of OAT procedures were isolated, while 52% were performed with concomitant procedures including meniscus allograft transplantation (MAT) in 65 (36%). Sixty-six patients (37%) underwent a reoperation at a mean of 2.5 ± 2.5 years, with 32% (21/66) undergoing additional reoperations (range, 1-3). Arthroscopic debridement was performed in 91% of patients with initial reoperations, with 83% showing evidence of an intact graft; of these, 9 ultimately progressed to failure at a mean of 4.1 ± 1.9 years. A total of 24 patients (13%) were considered failures at a mean of 3.6 ± 2.6 years after the index OAT procedure because of revision OAT (n = 7), conversion to arthroplasty (n= 12), or appearance of a poorly incorporated allograft at arthroscopic surgery (n = 5). The number of previous surgical procedures was independently predictive of reoperations and failure; body mass index was independently predictive of failure. Excluding the failed patients, statistically and clinically significant improvements were found in the Lysholm score, International Knee Documentation Committee score, Knee injury and Osteoarthritis Outcome Score, and Short Form-12 physical component summary at final follow-up ( P < .001 for all), with inferior outcomes (albeit overall improved) in patients who underwent a reoperation.

CONCLUSION

In this series, there was a 37% reoperation rate and an 87% allograft survival rate at a mean of 5 years after OAT. The number of previous ipsilateral knee surgical procedures was predictive of reoperations and failure. Of the patients who underwent arthroscopic debridement with an intact graft at the time of arthroscopic surgery, 82% experienced significantly improved outcomes, while 18% ultimately progressed to failure. This information can be used to counsel patients on the implications of a reoperation after OAT.

High tibial osteotomy combined with cancellous bone graft and osteochondral autograft transplantation in a patient with massive osteochondral defects in the medial femoral condyle

Treatment of massive osteochondral defects of the medial femoral condyle is challenging. A 46-year-old man who had a medial femoral condyle fracture on his left knee underwent osteosynthesis in a hospital, but the pain remained and the patient was referred to our hospital 8 months after the surgery. Radiographs showed a varus alignment of the leg, and magnetic resonance image showed a massive necrotic area in the medial femoral condyle. The patient received high tibial osteotomy (HTO) combined with iliac cancellous bone graft and an osteochondral autograft transplantation. Pain and the knee function markedly improved 2 years after the surgery. A second look arthroscopy showed a well-covered bone graft site with cartilaginous tissue and a well-integrated osteochondral plug. HTO combined with cancellous bone autograft and osteochondral autograft transplantation could be an effective treatment for patients presenting with a varus knee deformity associated with massive osteochondral defects in the medial femoral condyle.

The effects of low-dose radiotherapy on fresh osteochondral allografts: An experimental study in rabbits

Objective

The aim of this study was to investigate the effects of low-dose fractionated radiotherapy on cartilage degeneration after distal femoral fresh massive osteochondral allograft transplantation.

Methods

Twenty-four New Zealand White rabbits were divided into three groups of 8 rabbits each. All rabbits underwent distal femoral medial condyle fresh massive osteochondral allograft transplantation from California rabbits. The group 1 underwent transplantation without any preliminary process. The group 2 underwent fractionated local radiotherapy of 100 cGy for five days starting on the transplantation day. The group 3 included the rabbits to which the grafts transplanted after radiating in vitro by a single dose radiation of 1500 cGy. The hosts were sacrificed twelve weeks later. Anteroposterior and lateral radiographs were taken. Synovial tissue, cartilaginous tissue, and subchondral bone were assessed histopathologically.

Results

Nonunion was present in three cases of group 2 and one of group 3 in which cartilage degeneration was more severe. Synovial hypertrophy and pannus formation were more obvious in non-radiated rabbits. Hypocellularity and necrosis of the subchondral bone were rare in group 2. More cartilage tissue impairment was present in group 3 compared to group 1.

Conclusion

In osteochondral massive allograft transplantations, the immune reaction of the host could be precluded with radiotherapy, and the side-effects can be prevented by low-dose fractionated regimen. The total dose of fractionated radiotherapy for an immune suppression should be adjusted not to damage the cartilage tissue, but to avoid articular degeneration in the long term.

Cartilage defect repair in horses: Current strategies and recent developments in regenerative medicine of the equine joint with emphasis on the surgical approach

Chondral and osteochondral lesions due to injury or other pathology are highly prevalent conditions in horses (and humans) and commonly result in the development of osteoarthritis and progression of joint deterioration. Regenerative medicine of articular cartilage is an emerging clinical treatment option for patients with articular cartilage injury or disease. Functional articular cartilage restoration, however, remains a major challenge, but the field is progressing rapidly and there is an increasing body of supportive clinical and scientific evidence. This review gives an overview of the established and emerging surgical techniques employed for cartilage repair in horses. Through a growing insight in surgical cartilage repair possibilities, surgeons might be more stimulated to explore novel techniques in a clinical setting.

Articular Cartilage Injury and Potential Remedies

Osteoarthritis affects millions of people worldwide, is associated with joint stiffness and pain, and often causes significant disability and loss of productivity. Osteoarthritis is believed to occur as a result of ordinary "wear and tear" on joints during the course of normal activities of daily living. Posttraumatic osteoarthritis is a particular subset of osteoarthritis that occurs after a joint injury. Developing clinically relevant animal models will allow investigators to delineate the causes of posttraumatic osteoarthritis and develop means to slow or prevent its development after joint injury. Chondroprotectant compounds, which attack the degenerative pathways at a variety of steps, are being developed in an effort to prevent posttraumatic osteoarthritis and offer great promise. Often times, cartilage degradation after joint injury occurs despite our best efforts. When this happens, there are several evolving techniques that offer at least short-term relief from the effects of posttraumatic osteoarthritis. Occasionally, these traumatic lesions are so large that dramatic steps must be taken in an attempt to restore articular congruity and joint stability. Fresh osteochondral allografts have been used in these settings and offer the possibility of joint preservation. For patients presenting with neglected displaced intra-articular fractures that have healed, intra-articular osteotomy techniques are being developed in an effort to restore joint congruity and function. This article reviews the results of a newly developed animal model of posttraumatic osteoarthritis, several promising chondroprotectant compounds, and also cartilage techniques that are used when degenerative cartilage lesions develop after joint injury.

Cell-based cartilage repair strategies in the horse

Damage to the articular cartilage surface is common in the equine athlete and, due to the poor intrinsic healing capabilities of cartilage, can lead to osteoarthritis (OA). Joint disease and OA are the leading cause of retirement in equine athletes and currently there are no effective treatments to stop the progression of OA. Several different cell-based strategies have been investigated to bolster the weak regenerative response of chondrocytes. Such techniques aim to restore the articular surface and prevent further joint degradation. Cell-based cartilage repair strategies include enhancement of endogenous repair mechanisms by recruitment of stem cells from the bone marrow following perforation of the subchondral bone plate; osteochondral implantation; implantation of chondrocytes that are maintained in defects by either a membrane cover or scaffold, and transplantation of mesenchymal stem cells into cartilage lesions. More recently, bioengineered cartilage and scaffoldless cartilage have been investigated for enhancing repair. This review article focuses on the multitude of cell-based repair techniques for cartilage repair across several species, with special attention paid to the horse.

Fresh osteochondral allografts in the knee: only a salvage procedure?

The role of fresh allogeneic osteochondral allograft transplantation (OCA) in the cartilage repair algorithm has been long debated and this procedure is primarily considered as a salvage procedure, to be used when other, simple, techniques have failed. Gracitelli et al. in a retrospective comparison of patients who received OCA as primary treatment or as a salvage procedure, demonstrates that the outcome of this procedure is minimally influenced by a previous failed treatment and that OCA represents an effective solution for both primary and revision surgery of chondral and osteochondral lesions of the knee. In particular, optimal indications for OCA seem to be revision of previously failed bone marrow stimulation techniques with an impaired subchondral bone plate and primary treatment of large osteochondral defects.