Knee salvage procedures: The indications, techniques and outcomes of large osteochondral allografts

Infected Post-traumatic Bone Defect of the Knee using Bipolar Osteochondral Allograft and 3D Printing: A Case Report

Introduction

Transplantation with fresh cadaveric osteochondral allograft (FOCA) is frequently used in defects of the femoral condyle and tibial plateau to preserve the knee joint. However, the use of FOCA in bipolar lesions remains controversial in cases with bipolar defects and a history of infection.

Case Report

We present a 21-year-old male patient with a massive post-traumatic osteochondral defect of the lateral compartment of the knee and a history of infection, treated by a two-stage approach. In stage 1, infection was eradicated, and joint function recovered with aggressive debridement, polymethyl methacrylate beads, bone cement spacers, and Judet's quadricepsplasty. In stage 2, transplantation was performed with a bipolar FOCA. All treatments were planned using 3D-printed models.

Conclusion

The two-stage approach and 3D planning can increase the chances of transplant success by preparing the future allograft bed and obtaining an optimal match between the cadaveric allograft and the patient's defect in cases with potential contraindications, such as a bipolar lesion in the femoral condyle and tibial plateau and a history of infection. A combined approach may lead to a more beneficial outcome for the patient to preserve joint function and improve quality of life.

Comparison of Outcomes After Primary Versus Salvage Osteochondral Allograft Transplantation for Femoral Condyle Osteochondritis Dissecans Lesions

Background

Osteochondral allograft transplantation (OCAT) allows the restoration of femoral condyle osteochondritis dissecans (OCD) lesions using an osteochondral unit. When OCD lesions are irreparable, or treatments have failed, OCAT is an appropriate approach for revision or salvage surgery. Based on its relative availability, cost-effectiveness, lack of donor site morbidity, and advances in preservation methods, OCAT is also an attractive option for primary surgical treatment for femoral condyle OCD.

Hypothesis

OCAT for large femoral condyle OCD lesions would be highly successful (>90%) based on significant improvements in knee pain and function, with no significant differences between primary and salvage procedure outcomes.

Study Design

Cohort study; Level of evidence, 3.

Methods

Patients were enrolled into a registry for assessing outcomes after OCAT. Those patients who underwent OCAT for femoral condyle OCD and had a minimum of 2-year follow-up were included. Reoperations, treatment failures, and patient-reported outcomes were compared between primary and salvage OCAT cohorts.

Results

A total of 22 consecutive patients were included for analysis, with none lost to the 2-year follow-up (mean, 40.3 months; range, 24-82 months). OCD lesions of the medial femoral condyle (n = 17), lateral femoral condyle (n = 4), or both condyles (n = 1) were analyzed. The mean patient age was 25.3 years (range, 12-50 years), and the mean body mass index was 25.2 kg/m2 (range, 17-42 kg/m2). No statistically significant differences were observed between the primary (n = 11) and salvage (n = 11) OCAT cohorts in patient and surgical characteristics. Also, 91% of patients had successful outcomes at a mean of >3 years after OCAT with 1 revision in the primary OCAT cohort and 1 conversion to total knee arthroplasty in the salvage OCAT cohort. For both primary and salvage OCATs, patient-reported measures of pain and function significantly improved at the 1-year and final follow-up, and >90% of patients reported that they were satisfied and would choose OCAT again for treatment.

Conclusion

Based on the low treatment failure rates in conjunction with statistically significant and clinically meaningful improvements in patient-reported outcomes, OCAT can be considered an appropriate option for both primary and salvage surgical treatment in patients with irreparable OCD lesions of the femoral condyles.

Treatment failures (revision or arthroplasty) after knee osteochondral allograft transplantation with minimum two-year follow-up

BACKGROUND

Knee osteochondral allograft transplantation (OCAT) has been associated with good short- to mid-term outcomes, however, treatment failures occur more frequently than desired. This study used data from a lifelong outcomes registry to analyze knee OCAT treatment failure rates, variables associated with knee OCAT treatment failures, and outcomes after revision or arthroplasty surgery for knee OCAT treatment failures.

METHODS

Patient outcomes were followed after knee OCAT performed using standard preservation (SP) or Missouri Osteochondral Preservation System (MOPS®) allografts. The study population consisted of patients undergoing primary OCAT with ≥ 2-year follow-up. For comparisons, the treatment failure population was defined by patients in the study population with documented treatment failure (revision or arthroplasty) with ≥ 2-year follow-up after failure. Functional graft survival was defined as no further need for revision surgery after primary or revision OCAT.

RESULTS

A total of 262 patients (n = 136 males; 51.9%) were analyzed. SP grafts were used for 59 cases and MOPS grafts were used for 203 cases. Treatment failure was documented in 61 cases (23.3%). MOPS grafts were 3.3 times more likely to be associated with functional graft survival. SP grafts, older patient age, higher BMI, tibiofemoral bipolar OCAT and non-adherence to the postoperative rehabilitation protocol were significantly associated with treatment failure.

CONCLUSIONS

Knee OCAT resulted in functional graft survival at short- to mid-term follow-up in the majority (70-88%) of cases. In addition, revision of primary OCAT resulted in functional graft survival for at least 2 years after revision surgery in the majority (66%) of patients.

LEVEL OF EVIDENCE

2, prospective cohort study.

Young Age and Concomitant or Prior Bony Realignment Procedures are Associated with Decreased Risk of Failure of Osteochondral Allograft Transplantation in the Knee: A Nationwide Database Study

OBJECTIVE

Osteochondral allograft (OCA) transplantation is a restorative surgical option for large, full-thickness chondral or osteochondral defects in the knee. Variability in outcomes reporting has led to a broad range of graft survival rates. Using rate of salvage surgery following OCA as a failure metric, the purpose of this study was to analyze the incidence and risk factors for failure in a nationwide cohort.

DESIGN

The M151Ortho PearlDiver database was queried for patients aged 20 to 59 who underwent primary OCA between 2010 and 2020. Patients with prior cartilage procedures or arthroplasty were excluded. Kaplan-Meier survival analysis was performed to characterize cumulative rate of salvage surgery, defined as any patient subsequently undergoing revision OCA, autologous chondrocyte implantation (ACI), osteochondral autograft transfer system (OATS), unicompartmental knee arthroplasty (UKA), or total knee arthroplasty (TKA). Multivariable logistic regression was used to determine the effect of several variables on odds of salvage surgery.

RESULTS

Around 6,391 patients met inclusion criteria. Cumulative 5-year salvage rate was 1.71%, with 68.8% in the first 2 years. Age 20 to 29 and concomitant or prior bony realignment procedures were associated with significantly decreased rate of salvage surgery (age-adjusted odds ratio [aOR] = 0.49, 95% confidence interval [CI], 0.24-0.99, P = 0.046; realignment-aOR = 0.24, 95% CI, 0.04-0.75, P = 0.046).

CONCLUSIONS

In the largest OCA cohort studied to date, less than 2% of patients required salvage surgery. Young age and bony realignment were protective. These findings suggest that OCA in the knee is a durable cartilage-restoration procedure, especially in young patients with corrected alignment.

Return to Play After Knee Articular Cartilage Restoration: Surgical Options, Rehabilitation Protocols, and Performance Outcomes

PURPOSE OF REVIEW

Numerous cartilage restoration techniques have proven to be effective in the treatment of articular cartilage defects. The ultimate goal of these procedures is to improve pain and function, thereby increasing the likelihood of a patient's return to physical activity. Postoperative rehabilitation is a key component for a successful and expedient return to activities. The purpose of this article is to review the current literature regarding common surgical options, rehabilitation protocols, and performance outcomes after operative treatment of articular cartilage defects.

RECENT FINDINGS

Studies have demonstrated improved short- to long-term outcomes in a majority of techniques. However, the clinical benefits of microfracture are short-lived, which has led to the use of alternative procedures. Rehabilitation protocols are not standardized, but emphasis has been placed on bracing, weightbearing, early continuous passive range of motion, and strengthening to improve function. There is growing evidence to suggest that accelerated rehabilitation after matrix-induced autologous chondrocyte implantation may result in superior outcomes compared to delayed rehabilitation. Overall, most techniques result in satisfactory rates of return to play, though existing comparative studies typically include patients with heterogeneous pathology, complicating effective synthesis of outcomes data. In appropriately selected patients, cartilage restoration procedures after articular cartilage injury result in favorable patient-reported clinical outcomes and high rates of return to play. While studies emphasize the critical role that rehabilitation plays with respect to outcomes after surgery, there are substantial inconsistencies in protocols across techniques.

Revision Lateral Femoral Condyle Osteochondral Allograft Transplantation With the Snowman Technique After Failed Previous Oblong Osteochondral Allograft

Osteochondral allograft transplantation provides components of both cartilage and subchondral bone and can be used in large and multifocal defects where autologous procedures are limited by donor-site morbidity. Osteochondral allograft transplantation is particularly appealing in the management of failed cartilage repair, as larger defects and subchondral bone involvement are often present, and the use of multiple overlapping plugs might be considered. The described technique provides our preoperative workup and reproducible surgical approach for patients who have undergone previous osteochondral transplantation with graft failure and are young, active patients who would not be otherwise suited for a knee arthroplasty procedure.

The Biomimetics of Mg2+-Concentration-Resolved Microenvironment for Bone and Cartilage Repairing Materials Design

With the increase in population aging, the tendency of osteochondral injury will be accelerated, and repairing materials are increasingly needed for the optimization of the regenerative processes in bone and cartilage recovery. The local environment of the injury sites and the deficiency of Mg2+ retards the repairing period via inhibiting the progenitor osteogenesis and chondrogenesis cells’ recruitment, proliferation, and differentiation, which results in the sluggish progress in the osteochondral repairing materials design. In this article, we elucidate the Mg2+-concentration specified effect on the cell proliferation, osteochondral gene expression, and differentiation of modeling chondrocytes (extracted from New Zealand white rabbit) and osteoblasts (MC3T3-E1). The concentration of Mg2+ in the culture medium affects the proliferation, chondrogenesis, and osteogenesis: (i) Appropriate concentrations of Mg2+ promote the proliferation of chondrocytes (1.25−10.0 mM) and MC3T3-E1 cells (2.5−30.0 mM); (ii) the optimal concentration of Mg2+ that promotes the gene expression of noncalcified cartilage is 15 mM, calcified cartilage 10 mM, and subchondral bone 5 mM, respectively; (iii) overdosed Mg2+ leads to the inhibition of cell activity for either chondrocytes (>20 mM) or osteoblasts (>30 mM). The biomimetic elucidation for orchestrating the allocation of gradient concentration of Mg2+ in accordance of the physiological condition is crucial for designing the accurate microenvironment in osteochondral injury defects for optimization of bone and cartilage repairing materials in the future.

Osteochondral Allografts for Large Osteochondral Lesions of the Knee Joint: Indications, Surgical Techniques and Results

The main indications for osteochondral allografts (OCA) transplantation of the knee are the following: Symptomatic full-thickness cartilage lesions greater than 3 cm²; deep lesions with subchondral damage; and revision techniques when a previous surgical procedure has failed. Dowel and shell techniques are the two most commonly used for OCA transplantation. The dowel technique is appropriate in most cartilage lesions; however, geometrically irregular lesions may need the shell technique. Factors related to better outcomes after OCA transplantation are the following: unipolar lesions; patients younger than 30 years; traumatic lesions; and when the treatment is carried out within 12 months from the onset of symptoms. A systematic review found a survivorship rate of 89% at 5 years. Other systematic review showed a mean failure rate of 25% at 12 years with a reoperation rate of 36%. Seventy-two per cent of the failures were conversion to total knee arthroplasty (TKA) (68%) or unicompartmental knee arthroplasty (UKA) (4%). Twenty-eight per cent of failures were graft removal, graft fixation, and graft revision. In this systematic review, patellofemoral lesions (83%) had a higher reoperation rate than lesions affecting the tibial plateau or the femoral condyles. Overall, OCA transplantation showed a successful result in 75% of patients at 12 years follow-up.

Bipolar Cartilage Lesions of the Knee: A Systematic Review of Techniques, Outcomes, and Complications

OBJECTIVE

The purpose of this systematic review was to determine (1) treatment options for bipolar cartilage lesions of the knee, (2) patient-reported outcomes following various surgical treatments, and (3) complication and failure rates following surgery.

DESIGN

A literature search of PubMed, the Cochrane Library, and CINHAL was performed using PRISMA guidelines. Patients were included if they had bipolar cartilage lesions of the knee treated surgically. Lesion characteristics, surgical technique, patient-reported outcomes, complication rates, failure rates, and survivorship were recorded.

RESULTS

Fourteen studies yielded 301 knees treated surgically. Patient age ranged from 15 to 74 years. Surgical techniques included 138 autologous chondrocyte implantation (ACI), 156 osteochondral allograft transplantation (OCA), and 7 osteochondral autograft transfer system (OATS). Seven studies reported a concomitant procedure rate that ranged from 0% to 88%. Eight studies reported that both reciprocal lesions received surgical treatment, while 6 studies did not specify. Lesion size ranged from 1 to 41 cm². All reported postoperative improvements in patient-reported outcomes, but the measures were very heterogeneous. There were no major complications and the rate of minor complications ranged from 0% to 50%. Survivorship ranged from 40% to 100% for OCA, 76% to 95% for ACI, and 100% for the 1 study evaluating OATS.

CONCLUSIONS

Bipolar cartilage lesions of the knee typically involve a large surface area and are most commonly treated with ACI or OCA, while OATS may be an option for smaller lesions. Improvements in mid-term patient-reported outcomes were reported for all surgical procedures and they can be performed safely with a low rate of major complications.

Multiple Lesion Matrix-Induced Chondrocyte Implantation Procedure in a Collegiate Football Athlete: A Case Report

CASE

A 21-year-old male division I collegiate athlete presented for right knee pain, effusion, and mechanical symptoms. The patient was found to have 2.4 × 2-cm medial patellar facet, 1 × 0.8-cm central trochlea, and 2.5 × 3-cm lateral femoral condyle articular cartilage defects on arthroscopy. The patient was treated with a matrix-induced autologous chondrocyte implantation (MACI) procedure for all 3 lesions. At 9 months postoperatively, the patient returned to full American football activities and remains asymptomatic 16 months postoperatively.

CONCLUSION

Multiple lesions and lesions involving the patellofemoral joint can be treated with a MACI procedure with short-term promising results in high-demand athletes.

Cartilage Restoration of Bipolar Lesions Within the Patellofemoral Joint Delays Need for Arthroplasty: A Systematic Review of Rates of Failure

Purpose

The purpose of the present review is to systematically review the available literature for failure rates and complications of cartilage restoration of bipolar chondral defects in the patellofemoral (PF) joint to assess the ability to treat these lesions without arthroplasty.

Methods

PubMed and MEDLINE databases were queried between 2000 to 2020 using the keywords "osteochondral" and "knee" and "microfracture," "autologous chondrocyte implantation (ACI)," or "transplantation." Patient selection included patients with bipolar chondral lesions of the patellofemoral joint that were treated with cartilage restoration procedures. Treatment of PF joints were reviewed for surgical indications/technique, rates of failure, defect characteristics, and time to failure. For the purposes of this study, failure was defined by each individual author on their respective studies.

Results

After screening 1,295 articles, there were 8 publications analyzed quantitatively and 10 articles analyzed both quantitatively and qualitatively. A total of 249 knees involved bipolar lesions of the patellofemoral joint. The weighted average age was 36.5 ± 10.4 years, and weighted average follow-up was 89.0 ± 31.7 months. There were failures in 0% to 50% of cases, revision procedures in 0% to 10% of cases, conversion to arthroplasty in in 0% to 50% of cases, and unsatisfactory outcome without revision in 0% to 8.3% of cases. The range in average failure rate was 0% to 50.0% (I² = 68.0%), whereas the range in average time to failure was 2.9 to 6.8 years (I² = 79.0%).

Conclusion

From the available data, established cartilage restoration procedures may provide favorable patient-reported function, avoidance of secondary surgery, and joint preservation in at least 80% of patients at short- to mid-term follow-up.

Level of Evidence

Level IV, systematic review of Level IV studies.

Fresh Osteochondral Allograft Transplants in the Knee: Bipolar and Beyond

Knee patients who have sustained chondral and osteochondral lesions suffer from debilitating pain, which can ultimately lead to posttraumatic osteoarthritis and whole-joint disease. Older, nonactive patients are traditionally steered toward total knee arthroplasty (TKA), but younger, active patients are not good candidates for TKA based on implant longevity, complications, morbidity, and risk for revision, such that treatment strategies at restoring missing hyaline cartilage and bone are highly desired for this patient population. Over the past four decades, fresh osteochondral allograft (OCA) transplantation has been developed as a treatment method for large (> 2.5 cm²) focal full-thickness articular cartilage lesions. This article documents our own institutional OCA journey since 2016 through enhanced graft preservation techniques (the Missouri Osteochondral Preservation System, or MOPS), technical improvements in surgical techniques, use of bone marrow aspirate concentrate, bioabsorbable pins and nails, and prescribed and monitored patient-specific rehabilitation protocols. Further follow-up with documentation of long-term outcomes will provide insight for continued optimization for future applications for OCA transplantation, potentially including a broader spectrum of patients appropriate for this treatment. Ongoing translational research is necessary to blaze the trail in further optimizing this treatment option for patients.

Cartilage Injury in the Knee: Assessment and Treatment Options

Cartilage injuries in the knee are common and can occur in isolation or in combination with limb malalignment, meniscus, ligament, and bone deficiencies. Each of these problems must be addressed to achieve a successful outcome for any cartilage restoration procedure. If nonsurgical management fails, surgical treatment is largely based on the size and location of the cartilage defect. Preservation of the patient's native cartilage is preferred if an osteochondral fragment can be salvaged. Chondroplasty and osteochondral autograft transfer are typically used to treat small (<2 cm) cartilage defects. Microfracture has not been shown to be superior to chondroplasty alone and has potential adverse effects, including cyst and intralesional osteophyte formation. Osteochondral allograft transfer and matrix-induced autologous chondrocyte implantation are often used for larger cartilage defects. Particulated juvenile allograft cartilage is another treatment option for cartilage lesions that has good to excellent short-term results but long-term outcomes are lacking.

Arthroscopic Chondral Defect Repair With Extracellular Matrix Scaffold and Bone Marrow Aspirate Concentrate

Chondral defects of the knee are prevalent and often encountered during arthroscopic procedures. Despite the limited healing potential of chondral defects, several treatment options have been proposed. However, microfracture, osteochondral autograft (or allograft) transfer, autologous chondrocyte implantation, and matrix-induced autologous chondrocyte implantation are all associated with their respective shortcomings. As such, the optimal treatment for chondral defects of the knee remains unclear. Recently, many authors have advocated treating chondral defects with biological therapies and scaffold-based treatments. Bone marrow aspirate concentrate, a cell-based injection, has gained particular attention because of its differentiation capacity and potential role in tissue regeneration. In addition, scaffold cartilage treatments have emerged and reached clinical practice. BioCartilage is one form of scaffold, which consists of extracellular matrix, and has been claimed to promote the regeneration of hyaline-like cartilage. This article presents our technique of arthroscopic chondral defect repair using BMAC and BioCartilage.

Preservation of Knee Articular Cartilage

Hyaline articular cartilage is critical for the normal functioning of the knee joint. Untreated focal cartilage defects have the potential to rapidly progress to diffuse osteoarthritis. Over the last several decades, a variety of interventions aiming at preserving articular cartilage and preventing osteoarthritis have been investigated. Reparative cartilage procedures, such as microfracture, penetrate the subchondral bone plate in effort to fill focal cartilage defects with marrow elements and stimulate fibrocartilaginous repair. In contrast, restorative cartilage procedures aim to replace the defective articular surface with autologous or allogeneic hyaline cartilage. This review focuses on the preservation of articular cartilage, and discusses the current reparative and restorative surgical techniques available for treating focal cartilage defects.

Clinical Outcomes of Multifocal Osteochondral Allograft Transplantation of the Knee: An Analysis of Overlapping Grafts and Multifocal Lesions

BACKGROUND

There is a paucity of literature regarding the outcomes of adjacent-plug osteochondral allograft transplantation (OCA) for irregular or ovoid lesions and multifocal OCA for multicompartmental, focal lesions.

PURPOSE

To quantify the survival of multiplug OCA for larger, high-grade chondral lesions with the "snowman" technique versus that of multicompartmental or bipolar OCA.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

All patients who underwent primary, multiplug OCA for large unicondylar, multicompartmental (eg, bipolar patellofemoral and condylar, bicondylar), or bipolar chondral defects (ie, patellofemoral) with a minimum 2-year follow-up by a single surgeon from April 1, 2003, to April 1, 2015, were analyzed. Failure was defined as revision OCA, conversion to arthroplasty, or gross appearance of graft degeneration on second-look arthroscopic surgery.

RESULTS

Twenty-six patients (28 knees) were identified, with 22 patients (24 knees; 50% female; mean age, 31.9 ± 9.1 years) having at least 2-year clinical follow-up (85.7%). Nine patients (9 knees) underwent isolated, condylar OCA with the snowman technique and had a mean follow-up of 7.4 ± 3.6 years (range, 1.38-11.14 years), while 13 additional patients (15 knees) underwent multifocal OCA and had a mean follow-up of 6.4 ± 3.9 years (range, 2.07-12.38 years). Reoperations were common, with 44.4% (n = 4) of the snowman group and 20.0% (n = 3) of the multifocal group undergoing at least 1 reoperation. There were 3 failures (33.3%) in the snowman group at a mean 7.7 ± 5.5 years and 1 failure (6.7%) in the multifocal group at 4.5 ± 0.0 years, with all undergoing secondary total knee arthroplasty. Patients who underwent snowman OCA demonstrated significant postoperative improvement in the Knee injury and Osteoarthritis Outcome Score (KOOS) pain subscore and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) overall score ( P < .05 for both). Patients who underwent multifocal OCA demonstrated significant improvement in the International Knee Documentation Committee score; KOOS symptoms, activities of daily living, sport, and quality of life subscores; WOMAC stiffness, function, and overall subscores; and 12-Item Short Form Health Survey physical component summary score ( P < .05 for all).

CONCLUSION

Patients who underwent unicondylar, multiplug OCA using the snowman technique demonstrated inferior clinical outcomes, higher reoperation rates, and greater failure rates than those who underwent isolated single-graft transplantation. By contrast, multifocal OCA may be a viable knee preservation technique for young, active patients with multicompartmental chondral disease, leading to improved clinical outcomes and low reoperation and failure rates at midterm follow-up.

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.

Autologous Chondrocyte Implantation for Bipolar Chondral Lesions in the Tibiofemoral Compartment

BACKGROUND

Treating bipolar chondral lesions in the tibiofemoral (TF) compartment with cartilage repair procedures is challenging, and a suitable treatment remains unclear.

PURPOSE

To evaluate clinical outcomes after autologous chondrocyte implantation (ACI) for the treatment of bipolar chondral lesions in the TF compartment.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We evaluated 57 patients who underwent ACI for the treatment of symptomatic bipolar chondral lesions in the TF compartment by a single surgeon between October 1995 and June 2014. One patient did not return for follow-up. Thus, 56 patients (58 knees) were included with a minimum of 2 years' follow-up. A mean of 3.1 lesions per knee were treated, representing a mean total surface area of 16.1 cm² (range, 3.2-44.5 cm²) per knee. Bipolar lesions were present in the medial compartment (32 knees) and in the lateral compartment (26 knees). Patients were evaluated with the modified Cincinnati Knee Rating Scale, visual analog scale for pain, Western Ontario and McMaster Universities Osteoarthritis Index, and Short Form-36. Patients also answered questions regarding self-rated knee function and satisfaction with the procedure. Standard radiographs were evaluated with the Kellgren-Lawrence grading system.

RESULTS

The survival rate was 80% at 5 years and 76% at 10 years. A significantly better survival rate was found in patients with the use of a collagen membrane than periosteum (97% vs 61% at 5 years, respectively; P = .0014). Of 46 knees with retained grafts, all functional scores significantly improved postoperatively, with a very high satisfaction rate (91%) at a mean of 8.3 ± 5.1 years (range, 2-20 years) after ACI. At last follow-up, 24 of 46 successful knees were radiographically assessed (mean, 5.5 ± 4.0 years [range, 2.0-18.7 years]) and showed no significant osteoarthritis progression ( P = .3173). Outcomes for 12 patients were considered as failures at a mean of 4.1 years. Of these, 9 patients were converted to partial or total knee arthroplasty at a mean of 4.4 years. Two patients underwent revision ACI at 5 and 17 months. The other 1 patient did not require revision surgery.

CONCLUSION

Our study showed that ACI for the treatment of bipolar chondral lesions in the TF compartment provided successful clinical outcomes in patients with retained grafts and possibly prevented or delayed osteoarthritis progression at midterm to long-term follow-up. A collagen membrane is more encouraging than periosteum for bipolar lesions in the TF compartment. While addressing the predisposing factors affecting cartilage repair, ACI could be an adequate salvage procedure for bipolar chondral lesions in the TF compartment for the relatively young arthritic patient who wishes to avoid arthroplasty.

Osteoarticular Allograft Transplantation of the Trochlear Groove for Trochlear Dysplasia: A Case Report

CASE

A 21-year-old woman with recurrent lateral patellar instability caused by severe trochlear dysplasia and concomitant grade-IV trochlear chondromalacia was treated successfully with osteoarticular allograft transplantation of the entire trochlear groove.

CONCLUSION

The treatment of chronic lateral patellar instability caused by trochlear dysplasia can be challenging. When nonoperative treatment is unsuccessful, a sulcus-deepening trochleoplasty may be indicated. However, contraindications for a trochleoplasty include grade-IV chondromalacia of the patellofemoral joint. Even with this contraindication, an osteoarticular allograft transplant of the trochlear groove can serve as a salvage procedure to improve knee function.

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.

Fresh Osteochondral Allograft Transplantation: Is Graft Storage Time Associated With Clinical Outcomes and Graft Survivorship?

BACKGROUND

Regulatory concerns and the popularity of fresh osteochondral allograft (OCA) transplantation have led to a need for prolonged viable storage of osteochondral grafts. Tissue culture media allow a longer storage time but lead to chondrocyte death within the tissue. The long-term clinical consequence of prolonged storage is unknown.

HYPOTHESIS

Patients transplanted with OCAs with a shorter storage time would have lower failure rates and better clinical outcomes than those transplanted with OCAs with prolonged storage.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A matched-pair study was performed of 75 patients who received early release grafts (mean storage, 6.3 days [range, 1-14 days]) between 1997 and 2002, matched 1:1 by age, diagnosis, and graft size, with 75 patients who received late release grafts (mean storage time, 20.0 days [range, 16-28 days]) from 2002 to 2008. The mean age was 33.5 years, and the median graft size was 6.3 cm². All patients had a minimum 2-year follow-up. Evaluations included pain, satisfaction, function, failures, and reoperations. Outcome measures included the modified Merle d'Aubigné-Postel (18-point) scale, International Knee Documentation Committee (IKDC) form, and Knee Society function (KS-F) scale. Clinical failure was defined as revision OCA transplantation or conversion to arthroplasty.

RESULTS

Among patients with grafts remaining in situ, the mean follow-up was 11.9 years (range, 2.0-16.8 years) and 7.8 years (range, 2.3-11.1 years) for the early and late release groups, respectively. OCA failure occurred in 25.3% (19/75) of patients in the early release group and 12.0% (9/75) of patients in the late release group ( P = .036). The median time to failure was 3.5 years (range, 1.7-13.8 years) and 2.7 years (range, 0.3-11.1 years) for the early and late release groups, respectively. The 5-year survivorship of OCAs was 85% for the early release group and 90% for the late release group ( P = .321). No differences in postoperative pain and function were noted between the groups. Ninety-one percent of the early release group and 93% of the late release group reported satisfaction with OCA results.

CONCLUSION

The transplantation of OCA tissue with prolonged storage is safe and effective for large osteochondral lesions of the knee and has similar clinical outcomes and satisfaction to the transplantation of early release grafts.

Fresh osteochondral allografts-procurement and tissue donation in Europe

Fresh osteochondral allografts are a well-established treatment for large, full-thickness cartilage defects. The clinical outcome for carefully selected patients is very favorable, especially for the young and active and graft survival up to 25 years has been described in the literature. Furthermore, a high patient satisfaction rate has been reported, but the biggest obstacle to overcome is the availability of tissue for transplantation. Large fresh bone allografts for cartilage damage repair only can be harvested from organ donors following organ removal or cadaveric donors, preferably in the setting of an operation room to minimize possible contamination of the tissue. Apart from the logistic challenges this entails, an experienced recovery team is needed. Furthermore, the public as well as medical staff is much less aware of the possibility and requirements of tissue donation than organ donation and families of deceased are rarely approached for bone and cartilage donation. This review aims to highlight the current situation of organ and tissue donation in Europe with special focus on the processing of bones and possible safety and quality concerns. We analyze what may prevent consent and what might be done to improve the situation of tissue donation.

Osteochondral lesion depth on MRI can help predict the need for a sandwich procedure

PURPOSE

Autologous subchondral bone grafting in combination with autologous chondrocyte implantation (ACI) (sandwich procedure) is a well-accepted procedure for the treatment of osteochondral lesions of the knee. This requires a different surgical technique and preoperative planning compared to ACI alone. In addition, pain from bone marrow donor site locations can be expected and should be part of patient consent and expectations. This study evaluates whether the MRI made as part of the standard preoperative cartilage patient work up has the diagnostic accuracy to predict the need for a sandwich procedure.

METHODS AND MATERIALS

Retrospectively, 185 preoperative MRI scans (PD and T2 sequences) of patients planned for ACI were included. The integrity of the subchondral bone and lamina was scored by four different observers (3 radiologists, and 1 orthopaedic resident). The depth of the defect was measured perpendicular from articulating surface to the bottom of the bony lesion. The area under the curve (AUC) for subchondral defect on MRI (i.e. lamina or bone defect or expert impression), depth measurements and eventual sandwich procedure were calculated. Also inter-observer Kappa values were determined.

RESULTS

The AUCs for lamina (0.74-0.80) and bone defect (0.73-0.79) were fair and inter-observer Kappas ranged from 0.49 to 0.76, indicating a moderate-good inter-observer agreement and moderate prediction of the need for a sandwich procedure based on the presence of lamina and or subchondral bone defect on MRI. However, depth measurements resulted in an AUC of 0.90 (95% CI: 0.84-0.95,) with an optimal cut-off point at 6.5mm depth of the lesion (90% sensitivity, 80% specificity) to predict the need for a sandwich procedure.

CONCLUSION

Ours is the first study examining MRI as a diagnostic tool in predicting the need for a sandwich procedure. Our results show that the integrity of the subchondral layer on MRI has a moderate role in predicting the need for an eventual autologous bone graft to augment ACI whereas in our cohort a depth of the lesion above 6.5mm accurately predicts the need for a sandwich procedure. This can aid in optimising the preoperative planning and patient consent.

Immunology and cartilage regeneration

The intrinsic regenerative capacity of avascular cartilage is limited. Cartilage injuries result in chronic, non-healing lesions requiring surgical management. Frequently, these surgical techniques make use of allogeneic cells and tissues. This review discusses the immune status of these materials. Cartilage allografts, often used in orthopedic and plastic surgeries, have rarely provoked a significant immune response. In whole cartilage transplants, the dense matrix produced by chondrocytes inhibits lymphocyte migration, preventing immune detection rendering them "antigen sequestered." It is unclear whether isolated chondrocytes are immune-privileged; chondrocytes express immune inhibitory B7 molecules, indicating that they have some ability to modulate immune reactions. Allogeneic cartilage grafts often involve a bony portion often retaining immunogenic cells and proteins-to facilitate good surgical attachment and concern that this may enhance inflammation and immune rejection. However, studies of failed cartilage grafts have not found immune responses to be a contributing factor. Meniscus allografts, which also retain a bony portion, raise similar concerns as cartilage allografts. Despite this, the plugs improved patient outcomes, indicating that the immunological effects were not clinically significant. Finally, allogeneic mesenchymal stromal cells (MSCs) also are being investigated as a treatment for cartilage damage. MSCs have been demonstrated to have unique immunomodulatory properties including their ability to reduce immune cell infiltration and to modulate inflammation. In summary, the immunogenic properties of cartilage vary with the type of allograft used: Cartilage allografts demonstrate active immune-suppressive mechanisms as evidenced by lack of allograft rejection, while MSC allografts appear to be safe for transplantation.

Impact of storage conditions on electromechanical, histological and histochemical properties of osteochondral allografts

BACKGROUND

Osteochondral allograft transplantation has a good clinical outcome, however, there is still debate on optimization of allograft storage protocol. Storage temperature and nutrient medium composition are the most critical factors for sustained biological activity of grafts before implantation. In this study, we performed a time-dependent in vitro experiment to investigate the effect of various storage conditions on electromechanical, histological and histochemical properties of articular cartilage.

METHODS

Osteochondral grafts derived from goat femoral condyles were frozen at -70 °C or stored at 4 °C and 37 °C in the medium supplemented with or without insulin-like growth factor-1 (IGF-1). After 14 and 28 days the cartilage samples were quantitatively analysed for electromechanical properties, glycosaminoglycan distribution, histological structure, chondrocyte viability and apoptosis. The results were compared between the experimental groups and correlations among different evaluation methods were determined.

RESULTS

Storage at -70 °C and 37 °C significantly deteriorated cartilage electromechanical, histological and histochemical properties. Storage at 4 °C maintained the electromechanical quantitative parameter (QP) and glycosaminoglycan expression near the normal levels for 14 days. Although hypothermic storage revealed reduced chondrocyte viability and increased apoptosis, these parameters were superior compared with the storage at -70 °C and 37 °C. IGF-1 supplementation improved the electromechanical QP, chondrocyte viability and histological properties at 37 °C, but the effect lasted only 14 days. Electromechanical properties correlated with the histological grading score (r = 0.673, p < 0.001), chondrocyte viability (r = -0.654, p < 0.001) and apoptosis (r = 0.416, p < 0.02). In addition, apoptosis correlated with glycosaminoglycan distribution (r = -0.644, p < 0.001) and the histological grading score (r = 0.493, p = 0.006).

CONCLUSIONS

Our results indicate that quality of allografts is better preserved at currently established 4 °C storage temperature. Storage at -70 °C or at 37 °C is unable to maintain cartilage function and metabolic activity. IGF-1 supplementation at 37 °C can enhance chondrocyte viability and improve electromechanical and histological properties of the cartilage, but the impact persists only 14 days. The correlations between cartilage electromechanical quantitative parameter (QP) and metabolic activity were detected. Our findings indicate that non-destructive assessment of cartilage by Arthro-BST is a simple and reliable method to evaluate allograft quality, and could be routinely used before implantation.