A prospective randomized clinical study of mosaic osteochondral autologous transplantation versus microfracture for the treatment of osteochondral defects in the knee joint in young athletes

Autologous chondrocyte implantation for full thickness articular cartilage defects of the knee

BACKGROUND

Treatments for managing articular cartilage defects of the knee, including drilling and abrasion arthroplasty, are not always effective. When they are, long-term benefits may not be maintained and osteoarthritis may develop. An alternative is autologous chondrocyte implantation (ACI), the surgical implantation of healthy cartilage cells into the damaged areas.

OBJECTIVES

To determine the efficacy and safety of ACI in people with full thickness articular cartilage defects of the knee.

SEARCH STRATEGY

We searched the Cochrane Bone, Joint and Muscle Trauma Group Specialised Register (3 December 2008), the Cochrane Central Register of Controlled Trials (The Cochrane Library 2008, Issue 4), MEDLINE (1950 to November Week 3 2008), EMBASE (1980 to Week 48 2008), SPORTDiscus (3 December 2008), the WHO International Clinical Trials Registry Platform (4 December 2008), and Current Controlled Trials (3 December 2008).

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing ACI with any other type of treatment (including no treatment or placebo) for symptomatic cartilage defects of the medial or lateral femoral condyle, femoral trochlea or patella.

DATA COLLECTION AND ANALYSIS

Review authors selected studies for inclusion independently. We assessed risk of bias based on adequacy of the randomisation and allocation concealment process, potential for selection bias after allocation and level of masking. We did not pool data due to clinical and methodological heterogeneity.

MAIN RESULTS

Six heterogeneous trials were identified with 431 participants. Methodological flaws of the included trials included incomplete follow-up and inadequate reporting of outcomes. Three trials compared ACI versus mosaicplasty. One reported statistically significant results in favour of ACI at one year in the numbers of people with 'good' or 'excellent' functional results. Conversely, another trial found significant improvement for the mosaicplasty group when assessed using one functional scoring system at two years, but no statistically significant differences based on two other scoring systems. A third trial found no difference between ACI and mosaicplasty, 10 months on average after the surgery.There was no statistically significant difference in functional outcomes at two years in single trials comparing ACI with microfracture or characterised chondrocyte implantation versus microfracture. The results of the sixth trial comparing matrix-guided ACI versus microfracture were undermined by the severe loss to follow-up.

AUTHORS' CONCLUSIONS

There is insufficient evidence to draw conclusions on the use of ACI for treating full thickness articular cartilage defects in the knee. Further good quality randomised controlled trials with long-term functional outcomes are required.

Knee Cartilage Defect Patients Enrolled in Randomized Controlled Trials Are Not Representative of Patients in Orthopedic Practice

OBJECTIVE

Knee cartilage defects represent a socioeconomic burden and may cause lifelong disability. Studies have shown that cartilage defects are detected in approximately 60% of knee arthroscopies. In clinical trials, the majority of these patients are excluded. This study investigates whether patients included in randomized controlled trials (RCTs) represent a selected group compared to general cartilage patients.

DESIGN

Published randomized clinical trials on cartilage repair studies were identified (May 2009) and analyzed to define common inclusion criteria that in turn were applied to all patients submitted to our cartilage repair center during 2008. Patient-administered Lysholm knee score was used to evaluate functional level at referral. In addition, previous surgery and size and localization of cartilage defects were recorded.

RESULTS

Common inclusion criteria in the referred patients and patients included in the published RCTs were single femoral condyle lesion, age range 18 to 40 years, and size of lesion range 3.2 to 4.0 cm(2). Six of 137 referred patients matched all the 7 RCTs. Previous cartilage repair and multiple lesions were associated with decreased Lysholm score (P < 0.002). Lysholm score was independent of age, gender, and time of symptoms from the defect.

CONCLUSION

The heterogeneity of the referred cartilage patients and the variation in inclusion criteria in the RCTs may question whether RCTs actually represent the general cartilage patients. The present study suggests that results from published RCTs may not be representative of the gross cartilage population.

6-year follow-up of 84 patients with cartilage defects in the knee. Knee scores improved but recovery was incomplete

BACKGROUND AND PURPOSE

The natural history of focal cartilage injury is largely unknown. In this study we investigated 6-year outcomes in patients with arthroscopically verified, focal, full-thickness cartilage injuries of the knee.

METHODS

In a previous report (baseline study) of 993 knee arthroscopies, 98 patients were less than 50 years old at baseline and showed grade 3–4 focal cartilage injury, as assessed with the International Cartilage Repair Society (ICRS) scale. In the present study, 84 of the 98 patients completed follow-ups at median 6.1 (5.3–7.8) years after baseline assessments. At baseline, the patients had undergone different types of cartilage repair (n = 34) or had no treatment or only debridement (n = 64) for their cartilage injury. The follow-up included evaluations with the ICRS knee evaluation form, the Lysholm score, and other knee evaluation tests. 68 patients underwent radiographic assessments with weight bearing.

RESULTS

Improvements compared to baseline were noted in the average ICRS functional score, visual analog scale (VAS) pain score, and the patients' rating of the function in the affected knee compared to the contra-lateral knee. However, the average ICRS activity level had decreased from baseline. The average Lysholm score was 76 (SD 21). 19 patients had Kellgren-Lawrence grades 2–3 in the affected knee and 6 patients had grades 2–3 in the contralateral knee. There was a statistically significant difference between affected and contralateral knees.

INTERPRETATION

Patients with arthroscopically diagnosed ICRS grade 3–4 cartilage injuries in the knee may show improvement in knee function over the following 5–8 years, with or without cartilage repair. However, knee function remains substantially affected. Further studies are needed to determine whether cartilage surgery can yield better functional outcomes than non-surgical or less invasive surgical treatments.

Can osteochondral grafting be augmented with microfracture in an extended-size lesion of articular cartilage?

BACKGROUND

Both microfracture and osteochondral autografting procedures have been useful in treating osteochondral lesions.

HYPOTHESIS

Combining microfracture and osteochondral autografting procedures can extend the size of lesions that can be treated with either technique.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Eight adult goats underwent osteochondral autograft transfer of a 4.5-mm femoral trochlea plug into an 8-mm full-thickness chondral defect. Microfracture was performed in the gap region surrounding the autograft. The animals were allowed normal activity until the end of the experiment at 6 months. At harvest, the knees were assessed grossly, and then evaluation was performed by histology, histomorphometry, biochemistry, and biomechanics.

RESULTS

The osteochondral plugs healed well, with integration of the bone and preservation of the chondral cap. The chondral gap between the host site articular cartilage and the transferred plug had decreased from 3 mm at implant to less than 0.1 mm. Histologic analysis demonstrated regions of variable cartilage repair, with integration of the cartilage layer at some sites but incomplete healing at others. Histomorphometry demonstrated filling of the chondral gap to 75% to 85% of the normal volume. Biochemical analysis revealed greater than 90% type II collagen at most sites, with some areas containing 80% type II collagen. Biomechanical indentation testing indicated that the repaired area had variable thickness and stiffness, with a trend of increased stiffness in the bulk graft and decreased softness at the proximal microfracture interface site.

CONCLUSION

The performance of a combined microfracture and osteochondral autograft transfer procedure to resurface a large chondral defect appears promising.

CLINICAL RELEVANCE

This combined technique shows promise for treatment of large chondral defects with a single operative procedure with autogenous tissue that is safe and potentially would have a shorter period of rehabilitation, similar to that of osteochondral transfers and microfracture, in a cost-effective setting.

Chondral resurfacing and high tibial osteotomy in the varus knee: survivorship analysis

BACKGROUND

Active patients with arthritic malalignment of the knee are difficult to manage. Arthroplasty, unicompartmental or total knee replacement, may not be appropriate in patients who desire to remain highly active. High tibial osteotomy has been recommended for the treatment of varus osteoarthritis to decrease pressure on the damaged medial compartment.

PURPOSE

To determine the length of time patients with varus gonarthrosis can avoid knee arthroplasty with chondral resurfacing (microfracture) and medial opening wedge high tibial osteotomy (HTO).

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

From 1995 to 2001, the senior authors performed a medial opening wedge HTO/microfracture in 106 knees (mean age, 52 years; range, 30-71 years). Survivorship was defined as not requiring knee arthroplasty after microfracture and HTO.

RESULTS

At 5 years, survivorship was 97%. At 7 years, survivorship was 91%. Twelve patients proceeded to arthroplasty at a mean of 81 months (range, 19-116 months). Follow-up was obtained for 90% of patients. At most recent follow-up, the mean Lysholm score was 71 (range, 5-100). At 3 years, the mean Lysholm score was 73, Tegner score was 2.8, and patient satisfaction was 7.9. At 5 years, the mean Lysholm score was 73, Tegner score was 3.8, and patient satisfaction was 7.5. At 9 years, the mean Lysholm score was 67, Tegner score was 3.1, and patient satisfaction was 7.5. Patients with medial meniscus injury at surgery were 9.2 times more likely to undergo arthroplasty than patients without (95% confidence interval [CI], 1.4-13.5; P = .015).

CONCLUSION

With 91% survivorship at 7 years, microfracture/HTO seems to contribute to a delay of knee replacement in active patients with varus gonarthrosis. Patients who proceeded to knee arthroplasty after combined HTO/microfracture had a mean delay of 81.3 months.

Articular Cartilage Injury in Athletes

Articular cartilage lesions in the athletic population are observed with increasing frequency and, due to limited intrinsic healing capacity, can lead to progressive pain and functional limitation over time. If left untreated, isolated cartilage lesions can lead to progressive chondropenia or global cartilage loss over time. A chondropenia curve is described to help predict the outcome of cartilage injury based on different lesion and patient characteristics. Nutriceuticals and chondroprotective agents are being investigated as tools to slow the development of chondropenia. Several operative techniques have been described for articular cartilage repair or replacement and, more recently, cartilage regeneration. Rehabilitation guidelines are being developed to meet the needs of these new techniques. Next-generation techniques are currently evaluated to optimize articular cartilage repair biology and to provide a repair cartilage tissue that can withstand the high mechanical loads experienced by the athlete with consistent long-term durability.

The effect of platelet rich plasma combined with microfractures on the treatment of chondral defects: an experimental study in a sheep model

OBJECTIVE

To evaluate the effect of autologous platelet rich plasma (PRP) combined with microfractures on the treatment of chondral defects. The hypothesis of the study was that PRP can enhance cartilage repair after microfractures.

METHODS

A chronic full-thickness chondral lesion of the medial femoral condyle was performed in 15 sheep. Animals were divided into three groups, according to treatment: group 1: microfractures; group 2: microfractures+PRP and fibrin glue gel; group 3: microfractures+liquid-PRP injection. Animals were sacrificed at 6 months after treatment. Macroscopic appearance was evaluated according to International Cartilage Repair Society (ICRS) score; cartilage stiffness was analyzed with an electromechanical indenter (Artscan 200); histological appearance was scored according to a modified O'Driscoll score. Comparison between groups for each outcome was performed with Kruskal-Wallis test, and Tukey's test for pairwise comparisons.

RESULTS

Macroscopic ICRS score of group 2 was significantly better than those of the other groups, and score of group 1 was significantly lower than those of the other groups. Scores of group 1 and 3 were significantly lower than that of normal cartilage. Mean cartilage stiffness of groups 1 and 3 was significantly lower than that of normal cartilage. Histological total scores of group 2 and 3 were significantly better than that of group 1.

CONCLUSIONS

PRP showed a positive effect on cartilage repair and restoration after microfractures. The procedure was more effective when PRP was used as a gel in comparison with liquid intra-articular injection. Histological analysis revealed that none of experimental treatments produced hyaline cartilage.

Treatment of chondral defects in the athlete's knee

PURPOSE

To determine which surgical technique(s) has improved outcomes and enables athletes to return to their preinjury level of sports and which patient and defect factors significantly affect outcomes after cartilage repair or restoration.

METHODS

We conducted a search of multiple medical databases, evaluating studies of articular cartilage repair in athletes.

RESULTS

We identified 11 studies for inclusion (658 subjects). Only 1 randomized clinical trial was identified. All other studies were prospective cohorts, case-control studies, or case series reporting results after either microfracture or autologous chondrocyte implantation (ACI) or osteoarticular transplantation (OATS). Eight different clinical outcomes measures were used. Better clinical outcomes were observed after ACI and OATS versus microfracture. Results after microfracture tended to deteriorate with time. The overall rate of return to preinjury level of sports was 66%. The timing of return to the preinjury level of sports was fastest after OATS and slowest after ACI. Defect size of less than 2 cm(2), preoperative duration of symptoms of less than 18 months, no prior surgical treatment, younger patient age, and higher preinjury and postsurgical level of sports all correlated with improved outcomes after cartilage repair, especially ACI. Results after microfracture were worse with larger defects. The rate of return to sports was generally lower after microfracture versus ACI or OATS, and if a patient was able to return to sports, performance was diminished as well.

CONCLUSIONS

Management of chondral defects in the athlete is complex and multifactorial. There is little high-level evidence to support one procedure over another, although good short-term and midterm outcomes with a fair rate of return to preinjury level of sports can be achieved with cartilage repair and restoration in the athlete.

LEVEL OF EVIDENCE

Level IV, systematic review.

Effectiveness of autologous chondrocyte implantation in cartilage repair of the knee: a systematic review of controlled trials

OBJECTIVE

The relative differences in effectiveness of subchondral stimulation, osteochondral grafts, and autologous chondrocyte implantation (ACI) are still unclear. It is the objective of this study to systematically review the literature on ACI compared to other treatments by clinical outcome and the quality of the repair tissue, including an assessment of the validity of these findings.

METHOD

The online databases PubMed, EMBASE, Cochrane Controlled Trial Register, CENTRAL, CINAHL, and BioMed were searched. Controlled trials comparing ACI with other methods of cartilage repair or placebo were included. Data on clinical outcome and the quality of the repair tissue was abstracted in duplicate. Study validity was assessed by individual components (randomization, blinded outcome assessment, sample size, attrition, percentage biopsies).

RESULTS

Nine studies were included. The internal validity of most of these studies was poor. Studies comparing ACI with subchondral stimulation have a higher quality and show no differences in clinical outcomes, but suggest better results in tissue quality. The high quality evidence comparing ACI with osteochondral grafts shows better clinical outcomes and higher tissue quality after ACI.

CONCLUSION

Among the included studies there is much inconsistency in methodological quality and findings. Regardless of these problems, the absolute differences between groups are fairly small, thus raising questions about their clinical importance. Future studies will be needed to answer the question of benefits of ACI compared to other treatments, and could profit from addressing and avoiding the problems seen in this group. Finally conclusions concerning long-term effects are still difficult.

Clinical experiences with autologous osteochondral mosaicplasty in an athletic population: a 17-year prospective multicenter study

BACKGROUND

Several methods are used to treat focal chondral and osteochondral defects on the weightbearing surfaces of synovial joints. Autologous osteochondral grafting is 1 option used to replace hyaline cartilage in the defect.

HYPOTHESIS

Mosaicplasty is effective in returning elite athletes to participation in sports.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

In 3 institutes, 354 of 383 patients were followed from 2 to 17 years (average, 9.6 years). The results of mosaicplasty were prospectively evaluated at 6 weeks, 3 months, 6 months, and yearly with patient-reported outcomes measures and radiographs.

RESULTS

Slight or moderate degenerative changes (Fairbank grade I or II) were detected preoperatively in 27% of the cases and in 36% of the cases at follow-up. Fairbank grade III changes were observed in 5 cases. An average radiographic deterioration of 0.32 on the Fairbank scale was detected (preoperative, 0.34; postoperative, 0.66). Good to excellent results were found in 91% of femoral mosaicplasties, 86% of tibial, and 74% of patellofemoral; 92% of talar mosaicplasties had similar results (Hannover ankle scoring system). Patellofemoral pain related to graft harvest was observed in 5% of cases. Second-look arthroscopies revealed good, congruent, gliding surfaces of the transplants and acceptable fibrocartilage coverage of donor sites in 16 patients and degenerative changes of the transplants in 5 cases. Histological evaluation revealed good graft incorporation in all 11 cases. Two infections and 3 deep venous thromboses occurred.

CONCLUSION

Despite a higher rate of preoperative osteoarthritic changes in the athletic patients, clinical outcomes of mosaicplasty in this group demonstrated a success rate similar to that of less athletic patients. Higher motivation resulted in better subjective evaluation. Slight deterioration in results occurred during the 9.6-year follow-up; thus, autologous osteochondral mosaicplasty may be a useful alternative for the treatment of 1.0- to 4.0-cm(2) focal chondral and osteochondral lesions in competitive athletes.

Advances in Tissue Engineering Techniques for Articular Cartilage Repair

The limited repair potential of human articular cartilage contributes to development of debilitating osteoarthritis and remains a great clinical challenge. This has led to evolution of cartilage treatment strategies from palliative to either reconstructive or reparative methods in an attempt to delay or "bridge the gap" to joint replacement. Further development of tissue engineering-based cartilage repair methods have been pursued to provide a more functional biological tissue. Currently, tissue engineering of articular cartilage has three cornerstones; a cell population capable of proliferation and differentiation into mature chondrocytes, a scaffold that can host these cells, provide a suitable environment for cellular functioning and serve as a sustained-release delivery vehicle of chondrogenic growth factors and thirdly, signaling molecules and growth factors that stimulate the cellular response and the production of a hyaline extracellular matrix (ECM). The aim of this review is to summarize advances in each of these three fields of tissue engineering with specific relevance to surgical techniques and technical notes.

Cell carriers as the next generation of cell therapy for cartilage repair: a review of the matrix-induced autologous chondrocyte implantation procedure

BACKGROUND

Since the first patient was implanted with autologous cultured chondrocytes more than 20 years ago, new variations of cell therapies for cartilage repair have appeared. Autologous chondrocyte implantation, a first-generation cell therapy, uses suspended autologous cultured chondrocytes in combination with a periosteal patch. Collagen-covered autologous cultured chondrocyte implantation, a second-generation cell therapy, uses suspended cultured chondrocytes with a collagen type I/III membrane. Today's demand for transarthroscopic procedures has resulted in the development of third-generation cell therapies that deliver autologous cultured chondrocytes using cell carriers or cell-seeded scaffolds.

PURPOSE

To review the current evidence of the matrix-induced autologous chondrocyte implantation procedure, the most widely used carrier system to date. Also discussed are the characteristics of type I/III collagen membranes, behavior of cells associated with the membrane, surgical technique, rehabilitation, clinical outcomes, and quality of repair tissue.

STUDY DESIGN

Systematic review.

METHODS

Relevant publications were identified by searching Medline from its inception (1949) to December 2007; peer-reviewed publications of preclinical and clinical cell behavior, manufacturing process, surgical technique, and rehabilitation protocols were identified. Preclinical and clinical studies were included if they contained primary data and used a type I/III collagen membrane.

RESULTS

Data from these studies demonstrate that patients treated with matrix-induced autologous chondrocyte implantation have an overall improvement in clinical outcomes. Reduced visual analog scale pain levels (range, 1.7-5.32 points) and improvements in the modified Cincinnati (range, 3.8-34.2 points), Lysholm-Gillquist (range, 23.09-47.6 points), Tegner-Lysholm (range, 1.39-3.9 points), and International Knee Documentation Classification scale (P <.05) were observed. Patients had good-quality (hyaline-like) repair tissue as assessed by arthroscopic evaluation (including International Cartilage Repair Society score), magnetic resonance imaging, and histology, as well as a low incidence of postoperative complications.

CONCLUSION

The findings suggest that matrix-induced autologous chondrocyte implantation is a promising third-generation cell therapy for the repair of symptomatic, full-thickness articular cartilage defects.

A prospective, randomized clinical study of osteochondral autologous transplantation versus microfracture for the treatment of osteochondritis dissecans in the knee joint in children

PURPOSE

The aim of this study was to compare the outcomes of the arthroscopic mosaic-type osteochondral autologous transplantation (OAT) and microfracture (MF) procedures for the treatment of osteochondritis dissecans (OCD) defects of the femoral condyles of the knee joint in children under the age of 18 years.

TYPE OF STUDY

Prospective, randomized clinical study.

METHODS

Between 2001 and 2005, a total of 50 children with a mean age of 14.3 years (12 to 18) and with symptomatic lesions of the OCD in the femoral condyle of the knee were randomized to undergo either the OAT or the MF procedure. Only those children with grade 3 or 4 (OCD) in the medial or lateral femoral condyle (according to International Cartilage Repair Society, ICRS) were included in the study. Forty-seven patients (94%) were available for follow-up. There were 25 patients in the OAT group and 22 patients in the MF group. The mean duration of symptoms was 23.54+/-4.24 months and the mean follow-up was 4.2 years (range from 3 to 6 y), and none of the children had prior surgical interventions to the affected knee. Children were evaluated using ICRS score, x-rays, magnetic resonance imaging, and second-look arthroscopies.

RESULTS

After 1 year, both groups had significant clinical improvement (P<0.05) and the ICRS functional and objective assessment showed that 23 of 25 (92%) patients had excellent or good results after OAT compared with 19 of 22 (86%) after MF (NS), but 19 of 23 (83%) after OAT and only 12 of 19 (63%) after MF procedure maintained excellent or good results after 4.2 years (range from 3 to 6 y). The MF group showed significant deterioration over the 4.2 years follow-up (P<0.05), but still had significant clinical improvement compared with pretreatment evaluation (P=0.004). There were 9 of 22 (41%) failures in the MF group, and none in the OAT group. Magnetic resonance imaging evaluation according to the ICRS evaluation system showed excellent or good repairs in 19 of 21 patients (91%) after OAT compared with 10 of 18 (56%) after MF.

CONCLUSIONS

At an average of 4.2 years follow-up, our prospective, randomized, clinical study in children under the age of 18 years has shown significant superiority of the mosaic-type OAT over MF for the treatment of osteochondritis dissecans defects in the knee. However, our study has shown that both MF and OAT give encouraging clinical results for children under the age of 18 years.

LEVEL OF EVIDENCE

Level 1: randomized controlled trial, significant difference.

Transcriptional profiling and biochemical analysis of mechanically induced cartilaginous tissues in a rat model

OBJECTIVE

To characterize patterns of molecular expression that lead to cartilage formation in vivo in a postnatal setting, by profiling messenger RNA expression across the time course of mechanically induced chondrogenesis.

METHODS

Retired breeder Sprague-Dawley rats underwent a noncritical-sized transverse femoral osteotomy. Experimental animals (n = 45) were subjected to bending stimulation (60 degrees cyclic motion in the sagittal plane for 15 minutes/day) of the osteotomy gap beginning on day 10 after the operation. Control animals (n = 32) experienced continuous rigid fixation. Messenger RNA isolated on days 10, 17, 24, and 38 after surgery was analyzed using a microarray containing 608 genes involved in skeletal development, tissue differentiation, fracture healing, and mechanotransduction. The glycosaminoglycan (GAG) content in the stimulated tissues was compared with that in native articular cartilage as a means of assessing the progression of chondrogenic development of the tissues.

RESULTS

The majority of the 100 genes that were differentially expressed were up-regulated in response to mechanical stimulation. Many of these genes are associated with articular cartilage development and maintenance, diarthrodial joint development, cell adhesion, extracellular matrix synthesis, signal transduction, and skeletal development. Quantitative real-time polymerase chain reaction results were consistent with the microarray findings. The GAG content of the stimulated tissues increased over time and was no different from that of articular cartilage on day 38 after surgery.

CONCLUSION

Our findings indicate that mechanical stimulation causes up-regulation of genes that are principally involved in joint cavity morphogenesis and critical to articular cartilage function. Further study of this type of stimulation may identify key signaling events required for postnatal hyaline cartilage formation.

The evidence for surgical repair of articular cartilage in the knee

The complex structure and biomechanical function of articular cartilage make chondral injuries a management challenge. Articular cartilage has limited, if any, capacity to heal and/or regenerate. Although the natural history of articular cartilage lesions has not been clearly studied, significant injuries are believed to progress, resulting in degenerative arthritis of the joint. Changes have been made in surgical techniques in an attempt to better manage these lesions, and a large industry has been built around arthroscopic and open surgical procedures for managing cartilage repair. However, there is limited evidence that any intervention significantly alters the natural history of these lesions. Randomized trials have been done to examine the outcomes of common restoration procedures performed in the United States today, such as microfracture, osteochondral autograft transfer, and autologous chondrocyte implantation. Because the natural history of articular cartilage lesions has not been defined, we can assess the utility of surgical interventions only by comparing methods.

Augmentation Strategies following the Microfracture Technique for Repair of Focal Chondral Defects

The operative management of focal chondral lesions continues to be problematic for the treating orthopedic surgeon secondary to the limited regenerative capacity of articular cartilage. Although many treatment options are currently available, none fulfills the criteria for an ideal repair solution, including a hyaline repair tissue that completely fills the defect and integrates well with the surrounding normal cartilage. The microfracture technique is an often-utilized, first-line treatment modality for chondral lesions within the knee, resulting in the formation of a fibrocartilaginous repair tissue with inferior biochemical and biomechanical properties compared to normal hyaline cartilage. Although symptomatic improvement has been shown in the short term, concerns about the durability and longevity of the fibrocartilaginous repair have been raised. In response, a number of strategies and techniques for augmentation of the first-generation microfracture procedure have been introduced in an effort to improve repair tissue characteristics and reduce long-term deterioration. Recent experimental approaches utilize modern tissue-engineering technologies including local supplementation of chondrogenic growth factors, hyaluronic acid, or cytokine modulation. Other second-generation microfracture-based techniques use different types of scaffold-guided in situ chondroinduction. The current article presents a comprehensive overview of both the experimental and early clinical results of these developing microfracture augmentation techniques.

Management of articular cartilage defects of the knee

Articular cartilage has a poor intrinsic capacity for healing. The goal of surgical techniques to repair articular cartilage injuries is to achieve the regeneration of organized hyaline cartilage. Microfracture and other bone marrow stimulation techniques involve penetration of the subchondral plate in order to recruit mesenchymal stem cells into the chondral defect. The formation of a stable clot that fills the lesion is of paramount importance to achieve a successful outcome. Mosaicplasty is a viable option with which to address osteochondral lesions of the knee and offers the advantage of transplanting hyaline cartilage. However, limited graft availability and donor site morbidity are concerns. Transplantation of an osteochondral allograft consisting of intact, viable articular cartilage and its underlying subchondral bone offers the ability to address large osteochondral defects of the knee, including those involving an entire compartment. The primary theoretical advantage of autologous chondrocyte implantation is the development of hyaline-like cartilage rather than fibrocartilage in the defect, which presumably leads to better long-term outcomes and longevity of the healing tissue. Use of synthetic scaffolds is a potentially attractive alternative to traditional cartilage procedures as they are readily available and, unlike allogeneic tissue transplants, are associated with no risk of disease transmission. Their efficacy, however, has not been proven clinically.

The subchondral bone in articular cartilage repair: current problems in the surgical management

As the understanding of interactions between articular cartilage and subchondral bone continues to evolve, increased attention is being directed at treatment options for the entire osteochondral unit, rather than focusing on the articular surface only. It is becoming apparent that without support from an intact subchondral bed, any treatment of the surface chondral lesion is likely to fail. This article reviews issues affecting the entire osteochondral unit, such as subchondral changes after marrow-stimulation techniques and meniscectomy or large osteochondral defects created by prosthetic resurfacing techniques. Also discussed are surgical techniques designed to address these issues, including the use of osteochondral allografts, autologous bone grafting, next generation cell-based implants, as well as strategies after failed subchondral repair and problems specific to the ankle joint. Lastly, since this area remains in constant evolution, the requirements for prospective studies needed to evaluate these emerging technologies will be reviewed.

Clinical Outcome and Return to Competition after Microfracture in the Athlete's Knee: An Evidence-Based Systematic Review

Microfracture is frequently used for articular cartilage repair in athletes. This study aimed to define the strength and weaknesses of this minimally invasive cartilage repair technique in the athletic population in an effort to optimize indications, functional outcome, and athletic participation after microfracture in the athlete's knee. A systematic analysis of original studies using microfracture in athletes was performed. Functional outcome was assessed by activity outcome scores, ability to return to sports participation, timing of the return to sport, level of postoperative sports activity, and continuation of athletic competition over time. Thirteen studies describing 821 athletes were included in the analysis with an average follow-up of 42 months. Good or excellent results were reported in 67% of athletes with normal International Knee Documentation Committee (IKDC) scores in 80% and significant increase of Lysholm scores, Tegner activity scores, and Knee injury and Osteoarthritis Outcome Score (KOOS) sports subscales. Return to sports was achieved in 66% at an average of 8 months after surgery, with return to competition at the preinjury level in 67%. Forty-nine percent of athletes continued to compete without change in level of play, while decreasing function was observed in 42% after 2 to 5 years. Athlete's age, preoperative duration of symptoms, level of play, lesion size, and repair tissue morphology affected sports activity after microfracture. Microfracture improves knee function and frequently allows for return to sports at the preinjury level, but deterioration of athletic function occurs in some patients. Several independent factors were identified that can help to optimize the return to athletic competition after microfracture in the athlete's knee.

Results of osteochondral autologous transplantation in the knee

Repair of full thickness defects of articular cartilage in the knee is difficult but important to prevent progression to osteoarthritis. The purpose of this retrospective study was to evaluate the clinical results of Osteochondral Autograft Transplant System (OATS) treatment for articular defects of the knee.Between 1999 and 2005, 15 knees (14 patients) were treated by the OATS technique. Age ranged from 27 to 52 years. Cartilage defects were up to 3.75 cm2. The mean follow-up was 42 months. Knee function was assessed by the Lysholmscore and International Knee Documentation Committee (IKDC) Subjective Knee Form. Six patients scored good or excellent. No patient had knee instability. Twelve of 13 patients returned to sports at an intermediate or high level. The subjective assessment score (0-10) changed from 4.7 before operation to 7.2 afterward (P=0.007). The OATS-technique resulted in a decrease in symptoms in patients with localized articular cartilage defects. We consider the OATS technique to be an appropriate treatment for cartilage defects to prevent progression of symptoms.

Long-term durability of autologous chondrocyte implantation: a multicenter, observational study in US patients

BACKGROUND

Autologous chondrocyte implantation for full-thickness lesions of the distal femur has demonstrated good short- to midterm clinical improvement. However, long-term durability (>5 years) of autologous chondrocyte implantation has not been evaluated in US patients to date.

HYPOTHESIS

Patients who improve from baseline to early follow-up will sustain improvement at later follow-up.

STUDY DESIGN

Case series, Level of evidence, 4.

METHODS

Cartilage Repair Registry patients with full-thickness distal femur lesions who were treated with autologous chondrocyte implantation before December 31, 1996 and had modified overall Cincinnati scores at baseline and 1- to 5-year follow-up scores were re-evaluated at 6- to 10-year follow-up. Autologous chondrocyte implantation durability was determined by comparing early (1-5 years) to long-term (6-10 years) outcomes. Adverse events and treatment failures were recorded. Results Seventy-two patients met eligibility criteria (at baseline: mean age, 37 years; mean lesion size, 5.2 cm(2); and overall condition score, 3.4 points [poor]). Eighty-seven percent of patients (47 of 54) who improved at the earlier follow-up period sustained a mean improvement in overall condition score of 3.8 points from baseline to the later follow-up period (P < .001). From baseline to 10-year follow-up (mean follow-up, 9.2 years), 69% improved, 17% failed, and 12.5% reported no change from baseline. Most failures (75% [9 of 12]) occurred at a mean follow-up of 2.5 years. Thirty patients (42%) had 42 operations after autologous chondrocyte implantation; 24 operations (57%) occurred in patients who met the study definition of failure.

CONCLUSION

Treatment with autologous chondrocyte implantation for large, symptomatic, full-thickness lesions of the distal femur can result in early improvement that is sustained at longer follow-up (up to 10 years) in the majority of patients.

Osteochondral transfer using a transmalleolar approach for arthroscopic management of talus posteromedial lesions

Characterizing osteochondral lesions of the talus has enabled the strategies of surgical management to be better specified. The main technical problem is one of access for arthroscopy instruments to posteromedial lesions. A range of techniques and approaches has been described in ankle arthroscopy in general, and a transmalleolar approach provides reliable and efficient access in these cases. It is frequently used for transchondral drilling, but also enables satisfactory implant positioning in autologous osteochondral mosaicplasty procedures. We report our technique and results on five cases with a minimum 1.2 years' follow-up.

Return to sports participation after articular cartilage repair in the knee: scientific evidence

BACKGROUND

Articular cartilage injury in the athlete's knee presents a difficult clinical challenge. Despite the importance of returning injured athletes to sports, information is limited on whether full sports participation can be successfully achieved after articular cartilage repair in the knee.

HYPOTHESIS

Systematic analysis of athletic participation after articular cartilage repair will demonstrate the efficacy of joint surface restoration in high-demand patients and help to optimize outcomes in athletes with articular cartilage injury of the knee.

STUDY DESIGN

Systematic review.

METHODS

A comprehensive literature review of original studies was performed to provide information about athletic participation after articular cartilage repair. The athlete's ability to perform sports postoperatively was assessed by activity outcome scores, rate of return to sport, timing of the return, level of postoperative sports participation, and the continuation of athletic activity over time.

RESULTS

Twenty studies describing 1363 patients were included in the review, with an average follow-up of 42 months. Return to sports was possible in 73% overall, with highest return rates after osteochondral autograft transplantation. Time to return to sports varied between 7 and 18 months, depending on the cartilage repair technique. Initial return to sports at the preinjury level was possible in 68% and did not significantly vary between surgical techniques. Continued sports participation at the preinjury level was possible in 65%, with the best durability after autologous chondrocyte transplantation. Several factors affected the ability to return to sport: athlete's age, preoperative duration of symptoms, level of play, lesion size, and repair tissue morphology.

CONCLUSION

Articular cartilage repair in the athletic population allows for a high rate of return to sports, often at the preinjury level. Return to sports participation is influenced by several independent factors. The findings provide pertinent information that is helpful for the clinical decision-making process and for the management of the athlete's postoperative expectations.

Second-look arthroscopic findings and clinical outcomes after microfracture for osteochondral lesions of the talus

BACKGROUND

Arthroscopic microfracture is frequently used to repair osteochondral lesions of the talus. However, despite the popularity of this technique, no study has been conducted on cartilage repair after microfracture by second-look arthroscopy.

PURPOSE

The purpose of the present study was to evaluate cartilage repair in osteochondral lesions of the talus by second-look arthroscopy and to compare arthroscopic findings with clinical outcomes 12 months postoperatively.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Second-look arthroscopies were performed in 20 ankles of 19 patients at 12 months postoperatively. Arthroscopic findings were classified using the Ferkel and Cheng staging system, and cartilage repair was assessed using the International Cartilage Repair System (ICRS). Clinical outcomes were evaluated using the American Orthopaedic Foot and Ankle Society (AOFAS) ankle-hindfoot scale.

RESULTS

According to the Ferkel and Cheng staging at second-look arthroscopy, 7 of the 20 ankles (35%) showed incomplete healing (stage D). In terms of ICRS overall repair grades, 8 ankles (40%) were abnormal (grade III). Mean AOFAS scores for Ferkel and Cheng stages A to C (n = 13) and stage D (n = 7) were 88.5 and 82.0 points, and those for ICRS repair grades I and II (n = 12) and grade III (n = 8) were 88.7 and 82.5, respectively. Good correlations were found between AOFAS scores and Ferkel and Cheng stages and ICRS grades. Overall, 90% of ankles achieved an excellent or good AOFAS score of over 80 points.

CONCLUSION

Second-look arthroscopic findings at 12 months postoperatively after microfracture for osteochondral lesions of the talus revealed that 40% of lesions were incompletely healed. Nevertheless, the majority of patients achieved a good clinical outcome. Furthermore, postoperative clinical scores were found to be correlated with ICRS repair grades.

Treatment selection in articular cartilage lesions of the knee: a systematic review

BACKGROUND

Several treatment options are available to repair articular cartilage lesions of the knee; however, evidence-based parameters for treatment selection are lacking.

PURPOSE

To identify parameters for valid treatment selection in the repair of articular cartilage lesions of the knee.

STUDY DESIGN

Systematic review.

METHODS

A systematic search was conducted in the databases EMBASE, MEDLINE, and the Cochrane collaboration. The retrieved articles were screened for relevance on title and abstract followed by a full-text study quality appraisal of the remaining articles. Eventually, a total of 4 randomized controlled trials were included.

RESULTS

Lesion size, activity level, and age were the influencing parameters for the outcome of articular cartilage repair surgery. Lesions greater than 2.5 cm(2) should be treated with sophisticated techniques, such as autologous chondrocyte implantation or osteochondral autologous transplantation, while microfracture is a good first-line treatment option for smaller (<2.5 cm(2)) lesions. Patients who are active show better results after autologous chondrocyte implantation or osteochondral autologous transplantation when compared with microfracture. Younger patients (<30 years) seem to benefit more from any form of cartilage repair surgery compared with those over 30 years of age.

CONCLUSION

Lesion size, activity level, and patient age are factors that should be considered in selecting treatment of articular cartilage lesions of the knee. In addition, these factors are a step toward evidence-based, instead of surgeon-preferred, treatment of articular cartilage lesions of the knee.

Patient profiling in cartilage regeneration: prognostic factors determining success of treatment for cartilage defects

BACKGROUND

Cartilage therapy for focal articular lesions has been implemented for more than a decade, and it is becoming increasingly available. What is still lacking, however, is analysis of patient characteristics to help improve outcome or select patients for specific treatment.

PURPOSE

To analyze the prognostic value of patient age and defect size, age, and location on clinical outcome 3 years after cartilage therapy.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Fifty-five patients (age, 35 +/- 9 years) were randomly selected from a prospective database. Each had a traumatic knee injury, each was treated for a focal cartilage lesion, and each was assessed with the Knee injury and Osteoarthritis Outcome Score (KOOS) 3 years after surgery. Patient characteristics (ie, patient age and defect size, age, and location) were tested for valid inclusion in the regression model. Multiple linear regression was used to determine which variables influenced clinical improvement. Binary KOOS scores were generated on the basis of age-matched healthy patients and assessed in a logistic regression analysis.

RESULTS

Normality tests confirmed normal distribution for each variable (P < .05). Defect size did not influence clinical improvement (P > .05). Clinical outcome regarding the treatment of medial defects was better than that of the lateral defects (10.38-25.26 points for the different KOOS subscales; P < .05). The KOOS improvement from baseline was better for patients > or =30 years compared with patients > or =30 years (7.31-29.24 points for the different KOOS subscales; P < .05). Patients with defects <24 months were more likely to report the age-matched healthy reference KOOS (odds ratio, 1.8-4.0; P < .05).

CONCLUSION

This study illustrates the influence of patient age and defect location and age on clinical outcome 3 years after treatment of a focal cartilage lesion in patients with a traumatic knee injury.

Clinical efficacy of the microfracture technique for articular cartilage repair in the knee: an evidence-based systematic analysis

BACKGROUND

Despite the popularity of microfracture as a first-line treatment for articular cartilage defects in the knee, systematic information on its clinical efficacy for articular cartilage repair and long-term improvement of knee function is not available.

HYPOTHESIS

Systematic analysis of the existing clinical literature of microfracture in the knee can improve the understanding of the advantages and limitations of this cartilage repair technique and can help to optimize its indications and clinical outcomes.

STUDY DESIGN

Systematic review.

METHODS

A comprehensive literature search was performed using established search engines (MEDLINE, EMBASE, CINAHL, Cochrane Central Register of Controlled Trials) to identify original human studies of articular cartilage repair with microfracture. Modified Coleman Methodology Scores were used to analyze the quality of the existing studies. Clinical efficacy of articular cartilage repair was evaluated by systematic analysis of short- and long-term functional outcome scores, macroscopic and microscopic repair cartilage quality, and findings of postoperative magnetic resonance imaging.

RESULTS

Twenty-eight studies describing 3122 patients were included in the review. The average follow-up was 41 months, with only 5 studies reporting follow-up of 5 years or more. Six studies were randomized controlled trials and the mean Coleman Methodology Score was 58 (range, 22-97). Microfracture effectively improved knee function in all studies during the first 24 months after microfracture, but the reports on durability of the initial functional improvement were conflicting. Several factors were identified that affected clinical outcome. Defect fill on magnetic resonance imaging was highly variable and correlated with functional outcome. Macroscopic repair cartilage quality positively affected long-term failure rate, while the influence of histologic repair tissue quality remained inconclusive.

CONCLUSION

This systematic analysis shows that microfracture provides effective short-term functional improvement of knee function but insufficient data are available on its long-term results. Shortcomings of the technique include limited hyaline repair tissue, variable repair cartilage volume, and possible functional deterioration. The quality of the currently available data on micro-fracture is still limited by the variability of results and study designs. Further well-designed studies are needed to determine the long-term efficacy of microfracture and to define its specific clinical indications compared to other cartilage repair techniques.

Formation of cartilage repair tissue in articular cartilage defects pretreated with microfracture and covered with cell-free polymer-based implants

The aim of our study was to evaluate the mid-term outcome of a cell-free polymer-based cartilage repair approach in a sheep cartilage defect model in comparison to microfracture treatment. Cell-free, freeze-dried implants (chondrotissue) made of a poly-glycolic acid (PGA) scaffold and hyaluronan were immersed in autologous serum and used for covering microfractured full-thickness articular cartilage defects of the sheep (n = 4). Defects treated with microfracture only served as controls (n = 4). Six months after implantation, cartilage implants and controls were analyzed by immunohistochemical staining of type II collagen, histological staining of proteoglycans, and histological scoring. Histological analysis showed the formation of a cartilaginous repair tissue rich in proteoglycans. Histological scoring documented significant improvement of repair tissue formation when the defects were covered with the cell-free implant, compared to controls treated with microfracture. Immunohistochemistry showed that the cell-free implant induced cartilaginous repair tissue and type II collagen. Controls treated with microfracture showed marginal formation of a mixed-type repair tissue consisting of cartilaginous tissue and fibro-cartilage. Covering of microfractured defects with the cell-free polymer-based cartilage implant is suggested to be a promising treatment option for cartilage defects and improves the regeneration of articular cartilage.

Multimodal approach in the use of clinical scoring, morphological MRI and biochemical T2-mapping and diffusion-weighted imaging in their ability to assess differences between cartilage repair tissue after microfracture therapy and matrix-associated autologous chondrocyte transplantation: a pilot study

OBJECTIVE

The aim of the present pilot study is to show initial results of a multimodal approach using clinical scoring, morphological magnetic resonance imaging (MRI) and biochemical T2-relaxation and diffusion-weighted imaging (DWI) in their ability to assess differences between cartilage repair tissue after microfracture therapy (MFX) and matrix-associated autologous chondrocyte transplantation (MACT).

METHOD

Twenty patients were cross-sectionally evaluated at different post-operative intervals from 12 to 63 months after MFX and 12-59 months after MACT. The two groups were matched by age (MFX: 36.0+/-10.4 years; MACT: 35.1+/-7.7 years) and post-operative interval (MFX: 32.6+/-16.7 months; MACT: 31.7+/-18.3 months). After clinical evaluation using the Lysholm score, 3T-MRI was performed obtaining the MR observation of cartilage repair tissue (MOCART) score as well as T2-mapping and DWI for multi-parametric MRI. Quantitative T2-relaxation was achieved using a multi-echo spin-echo sequence; semi-quantitative diffusion-quotient (signal intensity without diffusion-weighting divided by signal intensity with diffusion weighting) was prepared by a partially balanced, steady-state gradient-echo pulse sequence.

RESULTS

No differences in Lysholm (P=0.420) or MOCART (P=0.209) score were observed between MFX and MACT. T2-mapping showed lower T2 values after MFX compared to MACT (P=0.039). DWI distinguished between healthy cartilage and cartilage repair tissue in both procedures (MFX: P=0.001; MACT: P=0.007). Correlations were found between the Lysholm and the MOCART score (Pearson: 0.484; P=0.031), between the Lysholm score and DWI (Pearson:-0.557; P=0.011) and a trend between the Lysholm score and T2 (Person: 0.304; P=0.193).

CONCLUSION

Using T2-mapping and DWI, additional information could be gained compared to clinical scoring or morphological MRI. In combination clinical, MR-morphological and MR-biochemical parameters can be seen as a promising multimodal tool in the follow-up of cartilage repair.

Outcomes of microfracture in professional basketball players

Surgical treatment for chondral defects of the knee in competitive running and jumping athletes remains controversial. This study evaluated the performance outcomes of professional basketball players in the National Basketball Association (NBA) who underwent microfracture. Data from 24 professional basketball players from 1997 to 2006 was obtained and analyzed. NBA player efficiency ratings (PER) were calculated for two seasons before and after injury. A control group of 24 players was used for comparison. Study group and control group demographics including age, NBA experience, and minutes per game demonstrated no statistical difference. Mean time to return to an NBA game was 30.0 weeks from the time of surgery. The first season after returning to competition PER and minutes per game decreased by 3.5 (P < 0.01) and 4.9 min (P < 0.05), respectively. The 17 players who continued to play two or more seasons after surgery, the average reduction in their PER and minutes per game was 2.7 (P > 0.05) and 3.0 min (P < 0.26), respectively. A multivariant comparison versus controls demonstrated that power rating during the 2 years after surgery decreased by 3.1 (P < 0.01); while minutes per game decreased by 5.2 (P < 0.001). Twenty-one percent (n = 5 of 24) of the players treated with microfracture did not return to competition in an NBA game. On return to competition player performance and minutes per game are diminished.

TGF-beta3: A potential biological therapy for enhancing chondrogenesis

BACKGROUND

TGF-beta has been proposed to stimulate chondrogenesis through intracellular pathways involving small mothers against decapentaplegic proteins (Smads).

OBJECTIVE

To examine the use of exogenous TGF-beta3 to promote new hyaline cartilage formation.

METHODS

An overview of in vitro and in vivo evidence on the effects of TGF-beta3 on cartilage regeneration.

RESULTS/CONCLUSION

There is robust in vitro evidence suggesting a positive dose- and time-dependent effect of TGF-beta3 on anabolic chondrogenic gene markers such as alpha1-collagen type II and cartilage oligomeric matrix protein in human mesenchymal stem cells. TGF-beta3 cultured with silk elastin-like polymer scaffold carrier exhibits significantly increased glycosaminoglycan and collagen content. In vivo data showed that TGF-beta3 cultured with ovine mesenchymal stem cells in a chitosan scaffold stimulated the growth of hyaline cartilage that was fully integrated into host cartilage tissue of sheep. We highlight the potential for the clinical enhancement of cartilage formation through the use of TGF-beta3 with a suitable dose and scaffold carrier.

Osteochondral grafting: effect of graft alignment, material properties, and articular geometry

Osteochondral grafting for cartilage lesions is an attractive surgical procedure; however, the clinical results have not always been successful. Surgical recommendations differ with respect to donor site and graft placement technique. No clear biomechanical analysis of these surgical options has been reported. We hypothesized that differences in graft placement, graft biomechanical properties, and graft topography affect cartilage stresses and strains. A finite element model of articular cartilage and meniscus in a normal knee was constructed. The model was used to analyze the magnitude and the distribution of contact stresses, von Mises stresses, and compressive strains in the intact knee, after creation of an 8-mm diameter osteochondral defect, and after osteochondral grafting of the defect. The effects of graft placement, articular surface topography, and biomechanical properties were evaluated. The osteochondral defect generated minimal changes in peak contact stress (3.6 MPa) relative to the intact condition (3.4 MPa) but significantly increased peak von Mises stress (by 110%) and peak compressive strain (by 63%). A perfectly matched graft restored stresses and strains to near intact conditions. Leaving the graft proud by 0.5 mm generated the greatest increase in local stresses (peak contact stresses = 6.7 MPa). Reducing graft stiffness and curvature of articular surface had lesser effects on local stresses. Graft alignment, graft biomechanical properties, and graft topography all affected cartilage stresses and strains. Contact stresses, von Mises stresses, and compressive strains are biomechanical markers for potential tissue damage and cell death. Leaving the graft proud tends to jeopardize the graft by increasing the stresses and strains on the graft. From a biomechanical perspective, the ideal surgical procedure is a perfectly aligned graft with reasonably matched articular cartilage surface from a lower load-bearing region of the knee.

Chondrocyte death and cartilage degradation after autologous osteochondral transplantation surgery in a rabbit model

BACKGROUND

Autologous osteochondral transplantation surgery requires an impact force on the graft that may cause chondrocyte death and matrix degradation. This study attempted to determine the degree to which this occurs in a rabbit model shortly after the procedure.

HYPOTHESIS

Impaction of a press-fit autologous osteochondral graft in vivo results in chondrocyte necrosis, apoptosis, and matrix degradation at early time points.

STUDY DESIGN

Controlled laboratory study.

METHODS

Twenty New Zealand White rabbits underwent unilateral osteochondral transplantation (OT) surgeries, and 10, bilateral sham surgeries. Fifteen animals were sacrificed at time zero (10 sham-0 limbs, 10 OT-0 limbs), and 15, 4 days after surgery (10 sham-4 limbs, 10 OT-4 limbs). Chondrocyte viability/necrosis was determined with cell vital staining. Chondrocyte apoptosis was determined by TUNEL, Bcl-2, and M30 assays. Cartilage matrix degradation was determined by routine light and polarized light microscopy and COL2-3/4C(short) immunohistochemistry. Statistical analysis was performed with a 2-way analysis of variance (P < .05).

RESULTS

There were significantly fewer viable cells in OT-4 than in sham-4. A similar difference in cell viability was found in OT-0 versus sham-0. There were more TUNEL-positive cells in OT-4 as compared with OT-0, sham-0, and sham-4; however, there was little or no staining of Bcl-2 and M30. Mankin scores were higher in both OT groups versus both sham groups at time zero and day 4. The OT-4 group had positive staining for COL2-3/4C(short) that corresponded with a loss of collagen birefringence at the superficial zone.

CONCLUSION

Osteochondral transplantation procedures performed by tamping a press-fit graft induce chondrocyte necrosis and matrix metalloproteinase-mediated cartilage matrix degradation. However, apoptosis was not found to a major contributor to cell death in this model.

CLINICAL RELEVANCE

Results of osteochondral transplantation procedures may be improved by atraumatic insertion and fixation techniques or by pharmacologic agents that can block these degradative processes.

The effects of early or late treatment of osteochondral defects on joint homoeostasis: an experimental study in rabbits

A 3.5 x 4 mm tubular osteochondral defect was created on the right medial femoral condyles of 51 adult rabbits. In the control group (CG), defects were left untreated. In the early-(ETG) and late-(LTG) treatment groups, defects were treated by an osteoperiosteal graft 1 and 12 weeks, respectively, after the index procedure. Synovial fluid (SF) samples were collected regularly and proteoglycan fragments (PF), total collagen (TC) and collagenase (MMP-1) levels were measured. Rabbits were killed at 4 (early period), 12 (intermediate period), or 24 (late period) weeks postoperatively. Histological examination indicated a more successful healing in both grafting groups than in the CG, but without any difference at any time period between the grafting groups. In the CG, PF, and TC levels in SF increased continuously until the late period, indicating an ongoing degenerative activity in the joints. In contrast, SF marker levels in both grafting groups indicated that normalization in joint metabolism could be achieved-at least partially-after treatment. However, PF levels in the SF showed that the treatment of defects in earlier stages might result in better outcomes since the negative effects were more prominent in chronic stages, presumably due to the more prolonged period of disturbed homeostasis. Thus, histological values and SF marker levels indicated that treatment of osteochondral defects at any time of the disease had a positive effect on healing when compared to no treatment. Early treatment might better assist the recovery of joint homeostasis than late treatment.

Results and performance after microfracture in National Basketball Association athletes

BACKGROUND

Microfracture technique is commonly used to treat symptomatic chondral lesions of the knee. Performance outcomes and attrition rates associated with this injury/surgery in National Basketball Association athletes are unclear.

HYPOTHESIS

National Basketball Association players undergoing microfracture for symptomatic chondral lesions of the knee will have demonstrable differences in performance compared with preinjury and with matched controls.

STUDY DESIGN

Case control study; Level of evidence, 3.

METHODS

We evaluated 24 National Basketball Association players who underwent microfracture between 1997 and 2006. Descriptive data and performance data for the first full season preceding and following the index surgery were collected. Data were obtained from 48 matched controls. Univariate/multivariate statistical methods were used to assess change in performance and return to play.

RESULTS

Thirty-three percent (8 of 24) of National Basketball Association athletes who underwent microfracture surgery never returned to play in the National Basketball Association. Fourteen players returned to play in the National Basketball Association for >1 season. Within-group comparisons revealed that points scored (P = .008) and minutes played (P = .045) were reduced postoperatively. No performance variables were significantly different when averaged over 40 minutes of play. When compared with controls, cases experienced a significant decline in points per game (P = .013). Multiple regression analysis revealed that cases were 8.15 times less likely to remain in the National Basketball Association than controls (P = .005) after the index year.

CONCLUSION

Players undergoing microfracture for knee chondral injuries are at risk for not returning to the National Basketball Association postoperatively. With the exception of points per game, athletes returning exhibited similar performance postoperatively compared with matched controls.

Increased failure rate of autologous chondrocyte implantation after previous treatment with marrow stimulation techniques

BACKGROUND

Marrow stimulation techniques such as drilling or microfracture are first-line treatment options for symptomatic cartilage defects. Common knowledge holds that these treatments do not compromise subsequent cartilage repair procedures with autologous chondrocyte implantation.

HYPOTHESIS

Cartilage defects pretreated with marrow stimulation techniques will have an increased failure rate.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

The first 321 consecutive patients treated at one institution with autologous chondrocyte implantation for full-thickness cartilage defects that reached more than 2 years of follow-up were evaluated by prospectively collected data. Patients were grouped based on whether they had undergone prior treatment with a marrow stimulation technique. Outcomes were classified as complete failure if more than 25% of a grafted defect area had to be removed in later procedures because of persistent symptoms.

RESULTS

There were 522 defects in 321 patients (325 joints) treated with autologous chondrocyte implantation. On average, there were 1.7 lesions per patient. Of these joints, 111 had previously undergone surgery that penetrated the subchondral bone; 214 joints had no prior treatment that affected the subchondral bone and served as controls. Within the marrow stimulation group, there were 29 (26%) failures, compared with 17 (8%) failures in the control group.

CONCLUSION

Defects that had prior treatment affecting the subchondral bone failed at a rate 3 times that of nontreated defects. The failure rates for drilling (28%), abrasion arthroplasty (27%), and microfracture (20%) were not significantly different, possibly because of the lower number of microfracture patients in this cohort (25 of 110 marrow-stimulation procedures). The data demonstrate that marrow stimulation techniques have a strong negative effect on subsequent cartilage repair with autologous chondrocyte implantation and therefore should be used judiciously in larger cartilage defects that could require future treatment with autologous chondrocyte implantation.

Osteonecrosis of the knee: a review of three disorders

Osteonecrosis of the knee is a debilitating disease that is poorly understood. Originally described as a single disorder, it encompasses three distinct conditions: spontaneous osteonecrosis of the knee (SPONK), secondary osteonecrosis of the knee, and post-arthroscopic osteonecrosis of the knee. This article reviews the current knowledge of these distinct conditions by describing their etiology, pathology, and pathogenesis, as well as their clinical and radiographic presentations. The various treatment options available for each condition are reviewed, with a discussion of their rationale and indications, and a summary of results with various techniques. A thorough understanding of these conditions and their distinguishing features is critical to selecting the best treatment option for an individual patient.

Predictive value of prior injury on career in professional American football is affected by player position

BACKGROUND

The National Football League holds an annual combine where individual teams evaluate college football players The abstract goes here and covers two columns. likely to be drafted for physical skills, review players' medical history and imaging studies, and perform a physical examination.

PURPOSE

The purpose of this study was to test the effect of specific diagnoses and surgical procedures on the likelihood of playing and length of career in the league by position.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

A database for all players reviewed at the annual National Football League Combine by the medical staff of 1 National Football League team from 1987 to 2000 was created, including each player's orthopaedic rating, diagnoses, surgical procedures, number of games played, and number of seasons played in the National Football League. Athletes were grouped by position as follows: offensive backfield, offensive receiver, offensive line, quarterback, tight end, defensive line, defensive secondary, linebacker, and kicker. The percentage of athletes who played in the National Football League was calculated by position for each specific diagnosis and surgery.

RESULTS

The effect of injury on the likelihood of playing in the league varied by position. Anterior cruciate ligament injury significantly lowered the likelihood of playing in the league for defensive linemen (P = .03) and linebackers (P = .04). Meniscal injury significantly reduced the probability of playing (P < .05) and length of career (P = .002) for athletes in the defensive secondary. Shoulder instability had a significant effect on playing in the league for offensive (P = .03) and defensive linemen (P = .02), and shortened the length of career for defensive linemen (P = .016). Spondylolisthesis did not significantly reduce the chance of playing in the league for any position, while a history of spondylolysis had a significant effect for running backs (P = .01). Miscellaneous injuries (eg. acromioclavicular joint, knee medial collateral ligament, carpal fractures) had isolated position-specific effects.

CONCLUSION

The significant injuries and diagnoses appear congruent with the position-specific demands placed on the athletes. This information is useful to physicians and athletic trainers caring for college football athletes as well as those assessing these athletes at the National Football League Combine.

Current and novel approaches to treating chondral lesions

Total joint arthroplasty remains the most effective treatment to relieve pain and restore function in damaged and diseased joints; however, less invasive, more functional solutions are necessary for young, active patients who have chondral defects and are at the early stages of disease. Unfortunately, attempts at providing such a method have provided variable and often unsatisfactory outcomes. Unicondylar knee replacement, for example, is associated with a markedly higher rate of revision when compared with total knee arthroplasty, and there is a distinct probability of disease progression in the remaining joint compartments. Small metallic caps intended for filling the cartilage defects are commercially available, but the clinical follow-up of patients who have undergone this treatment is short. Although not yet in clinical use, synthetic polymeric implant scaffolds, with and without cell-seeding, are also under development. The biomechanical requirements for treating chondral lesions, like those of total knee arthroplasty, are wear and fixation. A lesion-filling implant must carry large joint loads without damaging the opposing tissue. Integration with surrounding cartilage and subchondral bone would enhance load-sharing and load transfer. The challenge of meeting these requirements is difficult, but new forms of computational models and in vitro tests can aid in establishing performance and in rapidly screening possible solutions.

Magnetization transfer contrast and T2 mapping in the evaluation of cartilage repair tissue with 3T MRI

PURPOSE

To use magnetization transfer (MT) imaging in the visualization of healthy articular cartilage and cartilage repair tissue after different cartilage repair procedures, and to assess global as well as zonal values and compare the results to T2-relaxation.

MATERIALS AND METHODS

Thirty-four patients (17 after microfracture [MFX] and 17 after matrix-associated autologous cartilage transplantation [MACT]) were examined with 3T MRI. The MT ratio (MTR) was calculated from measurements with and without MT contrast. T2-values were evaluated using a multiecho, spin-echo approach. Global (full thickness of cartilage) and zonal (deep and superficial aspect) region-of-interest assessment of cartilage repair tissue and normal-appearing cartilage was performed.

RESULTS

In patients after MFX and MACT, the global MTR of cartilage repair tissue was significantly lower compared to healthy cartilage. In contrast, using T2, cartilage repair tissue showed significantly lower T2 values only after MFX, whereas after MACT, global T2 values were comparable to healthy cartilage. For zonal evaluation, MTR and T2 showed a significant stratification within healthy cartilage, and T2 additionally within cartilage repair tissue after MACT.

CONCLUSION

MT imaging is capable and sensitive in the detection of differences between healthy cartilage and areas of cartilage repair and might be an additional tool in biochemical cartilage imaging. For both MTR and T2 mapping, zonal assessment is desirable.

[Autologous osteochondral transplants]

Osteochondral transplantation is a treatment option for restoring lesions of the cartilage surface and the underlying subchondral bone. For this technique, osteochondral cylinders are taken from less loaded regions of the knee joint and brought into the defect. It is based on press-fit implantation of osteochondral cylinders that are harvested from the mediocranial or laterocranial aspect of the patellofemoral joint with subsequent stable bony integration of the transplant. Indications for osteochondral transplantation must consider clinical, radiological, and magnetic resonance aspects, and concomitant pathologies of the joint should be eliminated. Isolated grade III and IV cartilage lesions in the load-bearing area of the medial or lateral femoral condyle are considered to be ideal indications for osteochondral transplantations. Further indications are retropatellar defects and lesions of the medial aspect of the talus. The technique is established for defects from 1 cm2 to 3 cm2. At this time, osteochondral transplantation is the only surgical method to achieve long-term coverage of the defect with hyaline cartilage. Donor site morbidity at the patellofemoral joint needs to be discussed because, particularly after the harvest of several cylinders, pain syndromes can develop. Therefore, the technique should be limited to two cylinders with a maximum diameter of 12 mm and one further cylinder with a smaller diameter.

The microfracture technique for the treatment of full-thickness articular cartilage lesions of the knee: midterm results

PURPOSE

The purpose of this study was to determine the effectiveness of the microfracture technique in the treatment of full-thickness articular cartilage lesions of the knee.

METHODS

In this study the midterm results of 90 patients (47 women and 43 men) with focal full-thickness articular cartilage lesions who had been managed with the microfracture technique are presented. The mean age of our patients was 34.5 years (range, 20 to 58), and 51 right and 39 left knees were treated. All of the articular lesions involved medial femoral condyles.

RESULTS

On the basis of follow-up at a mean of 68 months (range, 24 to 108 months), mean improvements in Lysholm knee scores (from 54.2 to 84.6 points), Tegner activity scale scores (from 2.6 to 5.2 points), and Oxford knee interrogation scores (from 23.1 to 44.8 points) were observed (P < .0001). Moreover, there was a strong and significant correlation between functional results and age younger than 35 years, size of defect less than 2 cm(2), non-weight-bearing surface, and body mass index lower than 25 kg/m(2), respectively (P < .001).

CONCLUSIONS

According to our midterm results, the microfracture technique is quite effective with regard to the improvement of daily activities with a favorable impact on pain relief and better functional results. Furthermore, we found that there was a correlation between functional results and age, size of defect, location of defect, and body mass index as prognostic parameters.

LEVEL OF EVIDENCE

Level IV, therapeutic case series.

[Therapy of articular cartilage lesions]

Lesions of adult articular cartilage do not heal or regenerate. They give rise to the development of osteoarthritis, and surgical treatment is necessary before the initiation of joint degeneration. Various treatment modalities ranging from microfracture to autologous mosaicplasty and autologous chondrocyte transplantation are available. Commonly they are distinguished by the presence or absence of cell transplantation. The treatment choice depends on size, depth, and location of the lesion; therefore exact classification is mandatory. The surgical procedure aims to reconstruct a physiological distribution of the biomechanical forces by surface restoration. Additional joint pathologies such as mechanical axis deviation, meniscal defects, and ligament insufficiencies threaten the surgical success and must be addressed simultaneously.