Autologous chondrocyte implantation to repair knee cartilage injury: ultrastructural evaluation at 2 years and long-term follow-up including muscle strength measurements

The biomechanical and functional outcomes of autologous chondrocyte implantation for articular cartilage defects of the knee: A systematic review

PURPOSE

Autologous chondrocyte implantation (ACI) is primarily performed in active, young patients to treat knee pain and functional limitations resulting from articular cartilage injury. Nevertheless, the functional outcomes of ACI remain poorly understood. This systematic review aimed to evaluate the biomechanical and functional outcomes of ACI.

METHODS

Ovid MEDLINE, Embase, and Web of Science were systematically searched using the terms 'Knee OR Knee joint AND Autologous chondrocyte implantation OR ACI'. Inclusion and exclusion criteria were used to screen publications by title, abstract, and full text. Study quality and bias were assessed by two reviewers. Means and standard deviations of all collected variables were calculated and presented in the review.

PROSPERO ID

CRD42021238768.

RESULTS

Nineteen articles including 20 ACI cohorts were included. In general, the average range of motion (ROM) improved with clinical (>5°) and statistical significance (p < 0.05) postoperatively: 130.5 ± 14.8° to 136.1 ± 10.2°. Knee strength significantly improved within the first two postoperative years but remained poorer than control groups at final follow-up. No statistical differences were found between ACI and control groups in their ability to perform functional activities like the 6-minute walk test.

CONCLUSION

Knee range of motion generally improved following ACI. Although, some studies reported that knee strengths remained significantly poorer than healthy controls, particularly >2-years postoperatively, implying that longer-term strength training may benefit patients.However, the volume of research and current level of evidence remain low, thus further research is required to better understand the impact of ACI on knee function and guide future rehabilitative protocols.

Functional outcomes after anterior cruciate ligament reconstruction: unravelling the role of time between injury and surgery, time since reconstruction, age, gender, pain, graft type, and concomitant injuries

BACKGROUND

Numerous individual, temporal, injury- and surgery-specific factors impact the functional capacity during rehabilitation, return to sports (RTS), and re-injury prevention after an anterior cruciate ligament (ACL) reconstruction.

PURPOSE

This multicentre cohort study evaluated the isolated and interactive contributions of time between injury and surgery, time since reconstruction, age, gender, pain, graft type, and concomitant injuries as to inertial sensor-assessed motor function after ACL reconstructions in multiple linear mixed model regressions.

METHODS

Anonymized data were retrieved from a nationwide German registry. In this cohort study, patients with an acute unilateral ACL rupture, with or without concomitant ipsilateral knee injuries, and having passed an arthroscopically assisted anatomic reconstruction were included. Potential predictors were age [years], gender/sex, time since reconstruction [days], time between injury and reconstruction [days], concomitant intra-articular injuries (isolated ACL tear, meniscal tear, lateral ligament, unhappy triad), graft type (hamstrings, patellar, or quadriceps tendon autograft), and pain during each measurement (visual analogue scale 0-10 cm). Repeated inertial motion unit-assessments of a comprehensive battery of classic functional RTS test were performed in the course of the rehabilitation and return to sports: Joint position sense/kinesthesia (Angle reproduction error [degrees]), Dynamic Balance Composite score [cm] of the Y-Balance test), drop jumps (Knee displacement [cm]), Vertical hop (Hopping height [mm]), Speedy jumps (Duration [seconds]), Side hops (Number of hops [n]), single leg hop for distance (hopping distance [cm]). Repeated measures multiple linear mixed models investigated the impact and nesting interaction of the potential predictors on the functional outcomes.

RESULTS

Data from 1441 persons (mean age 29.4, SD 11.8 years; 592 female, 849 male) were included. Most had an isolated ACL rupture: n = 938 (65.1%). Minor shares showed lateral ligament involvement: n = 70 (4.9%), meniscal tear: n = 414 (28.7%), or even unhappy triad: n = 15 (1%). Several predictors such as time between injury and reconstruction, time since reconstruction (estimates for n_days ranged from + .05 (i.e., an increase of the hopping distance of 0.05 cm per day since reconstruction occurs) for single leg hop for distance to + 0.17 for vertical hopping height; p < 0.001), age, gender, pain, graft type (patellar tendon graft: estimates between + 0.21 for Y-balance and + 0.48 for vertical hop performance; p < 0.001), and concomitant injuries contribute to the individual courses of functional abilities of the reconstructed side after ACL reconstruction. The unimpaired side was mostly influenced by sex, age, the time between injury and reconstruction (estimates between - 0.0033 (side hops) and + 0.10 (vertical hopping height), p < 0.001)), and time since reconstruction.

CONCLUSIONS

Time since reconstruction, time between injury and reconstruction, age, gender, pain, graft type, and concomitant injuries are not independent but nested interrelating predictors of functional outcomes after anterior cruciate ligament reconstruction. It might not be enough to assess them isolated; the knowledge on their interactive contribution to motor function is helpful for the management of the reconstruction (earlier reconstructions should be preferred) deficit-oriented function-based rehabilitation (time- and function based rehabilitation instead of solely a time- or function based approach) and individualized return to sports strategies.

Contributors to self-report motor function after anterior cruciate ligament reconstruction

Numerous functional factors may interactively contribute to the course of self-report functional abilities after anterior cruciate ligament  (ACL)-reconstruction. This study purposes to identify these predictors using exploratory moderation-mediation models in a cohort study design. Adults with post unilateral ACL reconstruction (hamstring graft) status and who were aiming to return to their pre-injury type and level of sport were included. Our dependent variables were self-reported function, as assessed by the the KOOS subscales sport (SPORT), and activities of daily living (ADL). The independent variables assessed were the KOOS subscale pain and the time since reconstruction [days]. All other variables (sociodemographic, injury-, surgery-, rehabilitation-specific, kinesiophobia (Tampa Scale of Kinesiophobia), and the presence or absence of COVID-19-associated restrictions) were further considered as moderators, mediators, or co-variates. Data from 203 participants (mean 26 years, SD 5 years) were finally modelled. Total variance explanation was 59% (KOOS-SPORT) and 47% (KOOS-ADL). In the initial rehabilitation phase (< 2 weeks after reconstruction), pain was the strongest contributor to self-report function (KOOS-SPORT: coefficient: 0.89; 95%-confidence-interval: 0.51 to 1.2 / KOOS-ADL: 1.1; 0.95 to 1.3). In the early phase (2-6 weeks after reconstruction), time since reconstruction [days] was the major contributor (KOOS-SPORT: 1.1; 0.14 to 2.1 / KOOS-ADL: 1.2; 0.43 to 2.0). Starting with the mid-phases of the rehabilitation, self-report function was no longer explicitly impacted by one or more contributors. The amount of rehabilitation [minutes] is affected by COVID-19-associated restrictions (pre-versus-post: - 672; - 1264 to - 80 for SPORT / - 633; - 1222 to - 45 for ADL) and by the pre-injury activity scale (280; 103 to 455 / 264; 90 to 438). Other hypothesised contributors such as sex/gender or age were not found to mediate the time or pain, rehabilitation dose and self-report function triangle. When self-report function is rated after an ACL reconstruction, the rehabilitation phases (early, mid, late), the potentially COVID-19-associated rehabilitation limitations, and pain intensity should also be considered. As, for example, pain is the strongest contributor to function in the early rehabilitation phase, focussing on the value of the self-report function only may, consequently, not be sufficient to rate bias-free function.

Towards Tailored Rehabilitation by Implementation of a Novel Musculoskeletal Finite Element Analysis Pipeline

Tissue-level mechanics (e.g., stress and strain) are important factors governing tissue remodeling and development of knee osteoarthritis (KOA), and hence, the success of physical rehabilitation. To date, no clinically feasible analysis toolbox has been introduced and used to inform clinical decision making with subject-specific in-depth joint mechanics of different activities. Herein, we utilized a rapid state-of-the-art electromyography-assisted musculoskeletal finite element analysis toolbox with fibril-reinforced poro(visco)elastic cartilages and menisci to investigate knee mechanics in different activities. Tissue mechanical responses, believed to govern collagen damage, cell death, and fixed charge density loss of proteoglycans, were characterized within 15 patients with KOA while various daily activities and rehabilitation exercises were performed. Results showed more inter-participant variation in joint mechanics during rehabilitation exercises compared to daily activities. Accordingly, the devised workflow may be used for designing subject-specific rehabilitation protocols. Further, results showed the potential to tailor rehabilitation exercises, or assess capacity for daily activity modifications, to optimally load knee tissue, especially when mechanically-induced cartilage degeneration and adaptation are of interest.

Biomechanical Changes of Repair Tissue after Autologous Chondrocyte Implantation at Long-Term Follow-Up

Objective. This study aims to describe biomechanical maturation process of repair tissue after cartilage repair with autologous chondrocyte implantation (ACI) at long-term follow-up. Design. After ACI, 40 patients underwent altogether 60 arthroscopic biomechanical measurements of the repair tissue at various time points during an up to 11-year follow-up period. Of these patients, 30 patients had full-thickness cartilage lesions and 10 had an osteochondritis dissecans (OCD) defect. The mean lesion area was 6.5 cm² (SD 3.2). A relative indentation stiffness value for each individually measured lesion was calculated as a ratio of repair tissue and surrounding cartilage indentation value to enable interindividual comparison. Results. Repair tissue stiffness improved during approximately 5 years after surgery. Most of the increase in stiffness occurred during the first 2 years. The curvilinear correlation between relative stiffness values and the follow-up time was 0.31 (95% CI 0.07-0.52), P = 0.017. The interindividual variation of the stiffness was high. Lesion properties or demographic factors showed no significant correlation to biomechanical outcome. The overall postoperative average relative stiffness was 0.75 (SD 0.47). Conclusions. Our clinical study describes a biomechanical maturation process of cartilage repair that may continue even longer than expected. A substantial increase in tissue stiffness proceeds for the first two years postoperatively. Minor progression proceeds for even longer. In some repairs, the biomechanical result was equal to native cartilage, suggesting hyaline-type repair. The variation in biomechanical results suggests substantial inconsistency in the structural outcome following ACI.

A Rabbit Femoral Condyle Defect Model for Assessment of Osteochondral Tissue Regeneration

Osteochondral tissue repair represents a common clinical need, with multiple approaches in tissue engineering and regenerative medicine being investigated for the repair of defects of articular cartilage and subchondral bone. A full thickness rabbit femoral condyle defect is a clinically relevant model of an articulating and load bearing joint surface for the investigation of osteochondral tissue repair by various cell-, biomolecule-, and biomaterial-based implants. In this protocol, we describe the methodology and 1.5- to 2-h surgical procedure for the generation of a reproducible, full thickness defect for construct implantation in the rabbit medial femoral condyle. Furthermore, we describe a step-by-step procedure for osteochondral tissue collection and the assessment of tissue formation using standardized histological, radiological, mechanical, and biochemical analytical techniques. This protocol illustrates the critical steps for reproducibility and minimally invasive surgery as well as applications to evaluate the efficacy of cartilage and bone tissue engineering implants, with emphasis on the usage of histological and radiological measures of tissue growth. Impact statement Although multiple surgical techniques have been developed for the treatment of osteochondral defects, repairing the tissues to their original state remains an unmet need. Such limitations have thus prompted the development of various constructs for osteochondral tissue regeneration. An in vivo model that is both clinically relevant and economically practical is necessary to evaluate the efficacy of different tissue engineered constructs. In this article, we present a full thickness rabbit femoral condyle defect model and describe the analytical techniques to assess the regeneration of osteochondral tissue.

Cartilage damage at the time of anterior cruciate ligament reconstruction is associated with weaker quadriceps function and lower risk of future ACL injury

PURPOSE

To determine whether articular cartilage damage noted at the time of primary anterior cruciate ligament reconstruction (ACLR) affects the likelihood of achieving ≥ 90% symmetry for isokinetic extension strength at 6 months after surgery or risk of recurrent ACL injury.

METHODS

Five hundred and eight patients underwent primary ACLR and diagnostic arthroscopy. All identified cartilage lesions were graded using the Outerbridge system. All patients underwent isokinetic strength testing. The association between cartilage Outerbridge grade and a ≥ 90% Limb Symmetry Index (LSI) and recurrent ACL injury risk at mean 38.7 month follow-up (SD 31.8) was evaluated via multivariate regression analysis.

RESULTS

Grade 2 or higher damage was present in 394 (77.5%) of patients, grade 3 or higher in 143 (28.1%) and grade 4 in 83 (16.4%) at time of ACLR. Ipsilateral ACLR graft rupture occurred in 31 (6.1%) of patients. Contralateral ACL injury occurred in 19 (3.7%). Patients with grade 2 or higher damage were significantly less likely to meet an LSI goal of ≥ 90% for fast (300°/s) isokinetic extension. There was no association with slow isokinetic extension. Cartilage lesion severity at or beyond grade 2 had a similar effect on isokinetic testing results regardless of compartment involvement or performance of microfracture. Patients with grade 2-4 cartilage damage were less likely to sustain a second ipsilateral ACL injury or a contralateral native ACL injury.

CONCLUSIONS

Cartilage damage seen at time of ACL reconstruction is common and associated with lower likelihood of achieving ≥ 90% symmetry for isokinetic extension strength at 6 months after surgery. However, lower recurrent ACL injury rates are seen in patients with concurrent cartilage damage. These data may inform future clinical decisions regarding operative managment of recurrent ACL injuries.

LEVEL OF EVIDENCE

III.

Rehabilitation before regenerative cartilage knee surgery: a new prehabilitation guideline based on the best available evidence

INTRODUCTION

Focal cartilage defects are an increasingly relevant clinical problem especially in athletes. Cartilage regenerative surgery (CRS) including microfracture and autologous chondrocyte implantation (ACI) to treat such isolated cartilage defects in the knee joint has been well established in the last two decades. In contradiction to high-level evidence concerning the surgical technique, cell-related issues, and clinical results, the knowledge about the optimal rehabilitation process is still sparse although the importance of optimizing the rehabilitation process has recently led to new research focus in this field. The preoperative time frame may be used to start rehabilitation which may fasten the postoperative recovery and optimize clinical outcome ("Prehabilitation"-PREHAB). The aim of this article, therefore, was to review the available literature on prehabilitation concepts and to present a prehabilitation guideline for CRS patients based on the best evidence available.

METHODS

A systemic literature research was conducted on rehabilitation for cartilage regenerative surgery as well as prehabilitation in knee joint procedures. From the available literature a prehabilitation concept was generated and tested in 10 ACI patients.

RESULTS

As the literature search found no studies addressing prehabilitation in CRS patients, an evidence-based PREHAB program has been compiled based on the available evidence from (a) studies addressing postoperative rehabilitation in CRS patients and (b) PREHAB studies on other knee procedures including TKA. This presented prehabilitation guideline has been tested in > 50 CRS patients and was found to be feasible as all of the patients showed a good compliance and were able to perform the protocol as suggested.

CONCLUSION

The presented PREHAB regimen may serve clinicians as a guideline for early rehabilitation of their CRS patients. Obviously, further research is mandatory to quantify its clinical effect and to demonstrate its cost-effectiveness and benefits in surgically treated patients.

Subjects with medial and lateral tibiofemoral articular cartilage defects do not alter compartmental loading during walking

BACKGROUND

Healthy cartilage is essential for optimal joint function. Although, articular cartilage defects are highly prevalent in the active population and hamper joint function, the effect of articular cartilage defects on knee loading is not yet documented. Therefore, the present study compared knee contact forces and pressures between patients with tibiofemoral cartilage defects and healthy controls. Potentially this provides additional insights in movement adaptations and the role of altered loading in the progression from defect towards OA.

METHODS

Experimental gait data collected in 15 patients with isolated cartilage defects (8 medial involvement, 7 lateral-involvement) and 19 healthy asymptomatic controls was processed using a musculoskeletal model to calculate contact forces and pressures. Differences between two patient groups and controls were evaluated using Kruskal-Wallis tests and individually compared using Mann-Whitney-U tests (alpha <0.05).

FINDINGS

The patients with lateral involvement walked significantly slower compared to the healthy controls. No movement adaptations to decrease the loading on the injured condyle were observed. Additionally, the location of loading was not significantly affected.

INTERPRETATION

The current results suggest that isolated cartilage defects do not induce significant changes in the knee joint loading distribution. Consequently, the involved condyle will capture a physiological loading magnitude that should however be distributed over the cartilage surrounding the defect. This may cause local degenerative changes in the cartilage and in combination with inflammatory responses, might play a key role in the progression from articular cartilage defect to a more severe OA phenotype.

Knee Joint Loading in Healthy Adults During Functional Exercises: Implications for Rehabilitation Guidelines

Study Design Controlled laboratory study. Background The inclusion of specific exercises in rehabilitation after knee injury is currently expert based, as a thorough description of the knee contact forces during different exercises is lacking. Objective To quantify knee loading during frequently used activities such as squats, lunges, single-leg hops, walking stairs, standing up, and gait, and to grade knee joint loading during these activities. Methods Three-dimensional motion-analysis data of 15 healthy adults were acquired during 9 standardized activities used in rehabilitation. Experimental motion data were processed using musculoskeletal modeling to calculate contact and shear forces on the different knee compartments (tibiofemoral and patellofemoral). Using repeated-measures analyses of variance, contact and shear forces were compared between compartments and exercises, whereas muscle and average maximum femoral forces were compared only between exercises. Results With the exception of squats, all therapeutic exercises imposed higher forces to the tibiofemoral joint compared to gait. Likewise, patellofemoral forces were greater during all exercises when compared to gait. Greater compartmental contact forces were accompanied by greater compartmental shear forces. Furthermore, force distribution over the medial and lateral compartments varied between exercises. With increased knee flexion, more force was imposed on the posterior portion of the condyles. Conclusion These results suggest that with careful selection of exercises, forces on an injured zone of the joint can be reduced, as the force distribution differs strongly between exercises. Based on the results, a graded exercise program for progressive knee joint loading during rehabilitation can be conceptualized. J Orthop Sports Phys Ther 2018;48(3):162-173. Epub 6 Jan 2018. doi:10.2519/jospt.2018.7459.

Quadriceps Strength in Patients With Isolated Cartilage Defects of the Knee: Results of Isokinetic Strength Measurements and Their Correlation With Clinical and Functional Results

Background:

Recent studies have found a significant deficit of maximum quadriceps strength after autologous chondrocyte implantation (ACI) of the knee. However, it is unclear whether muscular strength deficits in patients with cartilage damage exist prior to operative treatment.

Purpose:

To isokinetically test maximum quadriceps muscle strength and quantify the impact of possible strength deficits on functional and clinical test results.

Study Design:

Cross-sectional study; Level of evidence, 3.

Methods:

To identify clinically relevant muscular strength deficits, 24 patients (5 females, 19 males; mean age, 34.5 years; body mass index, 25.9 kg/m²) with isolated cartilage defects (mean onset, 5.05 years; SD, 7.8 years) in the knee joint underwent isokinetic strength measurements. Maximal quadriceps strength was recorded in 3 different testing modes: pure concentric contraction (flexors and extensors alternating work; con1), concentric-eccentric (only the extensors work concentrically and eccentrically; con2), and eccentric contraction in the alternating mode (ecc). Results were compared for functional performance (single-leg hop test), pain scales (visual analog scale [VAS], numeric rating scale [NRS]), self-reported questionnaires (International Knee Documentation Committee [IKDC], Knee Injury and Osteoarthritis Outcome Scale [KOOS]), and defect size (cm²).

Results:

Compared with the uninjured leg, significantly lower quadriceps strength was detected in the injured leg in all isokinetic working modes (con1 difference, 27.76 N·m [SD 17.47; P = .003]; con2 difference, 21.45 N·m [SD, 18.45; P =.025]; ecc difference, 29.48 N·m [SD, 21.51; P = .001]), with the largest deficits found for eccentric muscle performance. Moderate negative correlations were observed for the subjective pain scales NRS and VAS. The results of the IKDC and KOOS questionnaires showed low, nonsignificant correlations with findings in the isokinetic measurement. Moreover, defect sizes (mean, 3.13 cm²) were of no importance regarding the prediction of the strength deficit. The quadriceps strength deficit between the injured and the uninjured leg was best predicted by the results of the single-leg hop test.

Conclusion:

Patients with isolated cartilage defects of the knee joint have significant deficits in quadriceps muscle strength of the injured leg compared with the uninjured leg. The single-leg hop test may be used to predict quadriceps strength deficits. Future research should address whether preoperative strength training in patients with cartilage defects of the knee could be effective and should be taken into consideration in addition to surgical treatment.

Long-Term Outcomes after Autologous Chondrocyte Implantation: A Systematic Review at Mean Follow-Up of 11.4 Years

OBJECTIVE

Autologous chondrocyte implantation (ACI) has not been proven to be durable over the long-term. The purpose of this systematic review was (1) to evaluate activity level and knee function, (2) to evaluate reoperation and failure rates, and (3) to analyze risk factors for reoperation and failure of ACI at minimum long-term follow-up.

DESIGN

A comprehensive review was performed for studies with long-term outcomes after ACI for cartilage defect repair. Studies reported outcome scores such as Tegner score, Lysholm score, and International Knee Documentation Society (IKDC) score along with rates of failure and reoperation. Modified Coleman Methodology Scores were calculated to assess study methodological quality.

RESULTS

Nine studies with a total of 771 patients with a mean age of 33.4 ± 2.5 years, mean defect size of 5.9 ± 1.6 cm(2), and mean follow-up of 11.4 years were included. Tegner score, Lysholm score, and IKDC score change from preoperative to final follow-up was 1.1 (95% CI 0.8-1.4, P < 0.001), 24.9 points (95% CI 18.8-31, P < 0.001), and 16.5 points (95% CI 5.4-27.5, P < 0.01), respectively. The mean failure and reoperation rates were 18% and 37%, respectively. Increased age and lesion size (>4.5 cm(2)) were significantly correlated with increased risk of reoperation and failure.

CONCLUSIONS

Overall, ACI demonstrated successful outcomes in 82% of patients over the long-term. Increased patient age and lesion size greater than 4.5 cm(2) were risk factors for a higher reoperation and failure rate. Nonetheless, this review is limited by heterogeneity in surgical technique, and lesion and patient characteristics.

Long-term Outcomes After Osteochondral Autograft Transfer: A Systematic Review at Mean Follow-up of 10.2 Years

PURPOSE

To evaluate (1) activity level and knee function, (2) reoperation and failure rates, and (3) risk factors for reoperation and failure of osteochondral autograft transfer (OAT) at minimum long-term follow-up.

METHODS

A comprehensive review was performed for long-term outcomes after OAT. Studies reported on activity-based outcomes (Tegner Activity Scale) and clinical outcomes (Lysholm score and International Knee Documentation Committee score). Reoperation and failure rates, as defined by the publishing authors, were recorded for each study. Modified Coleman Methodology Scores were calculated to assess study methodological quality.

RESULTS

Ten studies with a total of 610 patients with an average age of 27.0 years at the time of surgery and a mean follow-up of 10.2 years were included. The mean defect size was 2.6 cm(2) (range, 0.9 to 20.0 cm(2)). The mean duration of symptoms before surgery was 4.8 years. From preoperative to final follow-up, International Knee Documentation Committee scores and Lysholm scores improved significantly by 42.4 (95% confidence interval [CI], 31.8 to 53.1, P < .001) and 21.1 (95% CI, 12.2 to 30.0, P < .01), respectively. Tegner score did not improve significantly (0.76, 95% CI, -0.83 to 2.36, P = .35). Overall failure rate was 28% and reoperation rate was 19%. Increased age, previous surgery, and defect size positively correlated with increased risk of failure. Concomitant surgical procedures negatively correlated with failure rate.

CONCLUSIONS

Overall, OAT showed successful outcomes in 72% of patients at long-term follow-up. Increased age, previous surgery, and defect size correlated positively with failure rate, whereas success improved with concomitant surgical procedures. Nonetheless, this systematic review is limited by heterogeneity in a surgical technique, lesion and patient characteristics, and reporting of nonstandardized outcome measures.

LEVEL OF EVIDENCE

Level IV, systematic review of Level I-IV studies.

A conceptual framework for a sports knee injury performance profile (SKIPP) and return to activity criteria (RTAC)

Injuries to the knee, including intra-articular fractures, ligamentous ruptures, and meniscal and articular cartilage lesions, are commonplace within sports. Despite advancements in surgical techniques and enhanced rehabilitation, athletes returning to cutting, pivoting, and jumping sports after a knee injury are at greater risk of sustaining a second injury. The clinical utility of objective criteria presents a decision-making challenge to ensure athletes are fully rehabilitated and safe to return to sport. A system centered on specific indicators that can be used to develop a comprehensive profile to monitor rehabilitation progression and to establish return to activity criteria is recommended to clear athletes to begin a progressive and systematic approach to activities and sports. Integration of a sports knee injury performance profile with return to activity criteria can guide clinicians in facilitating an athlete's safe return to sport, prevention of subsequent injury, and life-long knee joint health.

Significantly worse isokinetic hamstring-quadriceps ratio in patellofemoral compared to condylar defects 4 years after autologous chondrocyte implantation

PURPOSE

Detailed biomechanical analysis including isokinetic muscle strength measurements after autologous chondrocyte implantation (ACI) are still rare, but might be of crucial importance for long-term outcomes. The present prospective study was performed to evaluate whether defect location had any influence on clinical and biomechanical outcomes 4 years after ACI.

METHODS

Forty-four patients with full-thickness cartilage defects ICRS grade III B and C underwent ACI and were assigned to two groups, the femoral condyle group or the patellofemoral joint group. Clinical scores were gathered preoperatively and 6, 12 and 48 months after implantation using the International Knee Documentation Committee (IKDC) score and the International Cartilage Repair Society (ICRS) form. Isokinetic strength measurements were performed 48 months postoperatively comparing healthy and operated knee joint of each patient.

RESULTS

Clinical scores (ICRS, IKDC) showed continuous significant (p < 0.05) improvement over the study period for both groups. Isokinetic muscle strength measurements showed significantly reduced maximum strength capacities for the operated knee joint compared to the healthy knee in both groups (p < 0.05). Hamstring-quadriceps ratios of the operated extremity revealed a significant change in physiological muscle balancing (ratios >1.0) based on significantly impaired extensor muscle strength in the patellofemoral joint group.

CONCLUSION

All patients showed significant strength deficits on the operated extremity 4 years after ACI. Furthermore, the patellofemoral compartment in particular showed significantly worse hamstring-quadriceps ratios compared to condylar defects. Consequently, more efforts should be made to restore muscular strength especially of the quadriceps and the rehabilitation protocol should be adjusted accordingly.

LEVEL OF EVIDENCE

II.

Prospective clinical and radiologic evaluation of patellofemoral matrix-induced autologous chondrocyte implantation

BACKGROUND

While matrix-induced autologous chondrocyte implantation (MACI) has demonstrated encouraging outcomes in the treatment of knee chondral defects, there remains little available research specifically investigating its use in the patellofemoral joint.

PURPOSE

To prospectively evaluate the clinical and radiologic outcome of MACI in the patellofemoral joint.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

In 47 consecutive patients undergoing patellofemoral MACI, clinical (Knee injury and Osteoarthritis Outcome Score, 36-Item Short Form Health Survey, visual analog scale for pain, 6-minute walk test, knee range of motion, and strength assessment) and magnetic resonance imaging (MRI) assessments were undertaken before and 3, 12, and 24 months after surgery. The MRI was performed to assess graft infill and determine an overall MRI composite score. Results were analyzed according to (1) the patient sample overall and (2) after stratification into 4 subgroups per implant location (patella or trochlea) as well as whether or not adjunct tibial tubercle transfer for patellofemoral malalignment was required.

RESULTS

The overall patient sample, as well as each of the 4 procedural subgroups, demonstrated clinically and statistically significant (P < .05) improvements over time for all clinical scores. Graft infill and the MRI composite score also demonstrated statistically significant (P < .05) improvements over time, with no evidence of a main effect for procedure group or interaction between procedure group and time. At 24 months after surgery, 40.4% (n = 19) of patients exhibited complete graft infill comparable with the adjacent native cartilage, with a further 6.4% (n = 3) demonstrating a hypertrophic graft. A further 31.9% (n = 15) of patients exhibited 50% to 100% tissue infill, and 17% (n = 8) demonstrated <50% tissue infill. Two patients (4.3%) demonstrated graft failure. At 24 months after surgery, 85% (n = 40) of patients were satisfied with the results of their MACI surgery.

CONCLUSION

These results demonstrate that MACI provides improved clinical and radiologic outcomes to 24 months in patients undergoing treatment specifically for articular cartilage defects on the patella or trochlea, with and without concurrent realignment of the extensor mechanism if required.

Functional outcomes after surgical management of articular cartilage lesions in the knee: a systematic literature review to guide postoperative rehabilitation

STUDY DESIGN

Systematic literature review.

OBJECTIVE

To systematically review the literature relative to muscle performance, knee joint biomechanics, and performance-based functional outcomes following articular cartilage repair and restoration surgical procedures in the knee.

BACKGROUND

Articular cartilage injuries are associated with functional limitations, poor quality of life, and the potential for long-term disability. This review systematically evaluates evidence related to muscle performance, joint biomechanics, and performance-based functional outcomes following articular cartilage procedures, and discusses their implications for rehabilitation.

METHODS

The online databases of PubMed (MEDLINE), CINAHL, SPORTDiscus, and Scopus were searched (inception to September 2013). Studies pertaining to muscle performance, knee joint biomechanics, and performance-based measures of function following articular cartilage procedure in the knee were included.

RESULTS

Sixteen articles met the specified inclusion criteria. Seven studies evaluated muscle performance, all showing persistent deficits in quadriceps femoris muscle strength for up to 7 years postprocedure. Quadriceps femoris strength deficits of greater than 20% were noted in 33% and 26% of individuals at 1 and 2 years following microfracture and autologous chondrocyte implantation (ACI), respectively. Two studies evaluated knee mechanics post-ACI, showing persistent deficits in knee kinematics and kinetics for up to 12 months postprocedure compared to uninjured individuals. Seven studies showed improved functional capacity (6-minute walk test) over time, and 3 studies showed persistent performance deficits during higher-level activities (single-leg hop test) for up to 6 years postprocedure. Five studies comparing weight-bearing protocols (accelerated versus traditional/current practice) following ACI found few differences between the groups in function and gait mechanics; however, persistent gait alterations were observed in both groups compared to uninjured individuals.

CONCLUSION

Significant quadriceps femoris strength deficits, gait deviations, and functional deficits persist for 5 to 7 years following ACI and microfracture surgical procedures. Future research regarding rehabilitation interventions to help mitigate these deficits is warranted. Level of Evidence Prognosis, level 2a-.

Clinical rehabilitation guidelines for matrix-induced autologous chondrocyte implantation on the tibiofemoral joint

Autologous chondrocyte implantation (ACI) has become an established technique for the repair of full-thickness chondral defects in the knee. Matrix-induced ACI (MACI) is the third and current generation of this surgical technique, and, while postoperative rehabilitation following MACI aims to restore normal function in each patient as quickly as possible by facilitating a healing response without overloading the repair site, current published guidelines appear conservative, varied, potentially outdated, and often based on earlier ACI surgical techniques. This article reviews the existing evidence-based literature pertaining to cell loading and postoperative rehabilitation following generations of ACI. Based on this information, in combination with the technical benefits provided by third-generation MACI in comparison to its surgical predecessors, we present a rehabilitation protocol for patients undergoing MACI in the tibiofemoral joint that has now been implemented for several years by our institution in patients with MACI, with good clinical outcomes.

Is gender influencing the biomechanical results after autologous chondrocyte implantation?

PURPOSE

The influence of gender on the biomechanical outcome after autologous chondrocyte implantation (ACI) including isokinetic muscle strength measurements has not been investigated. The present prospective study was performed to evaluate gender-specific differences in the biomechanical function 48 months after ACI.

METHODS

Fifty-two patients (mean age 35.6 ± 8.5 years) that met our inclusion criteria, underwent ACI with Bioseed C(®) and were evaluated with the KOOS score preoperatively, 6, 12 and 48 months after surgery. At final follow-up, 44 out of the 52 patients underwent biomechanical evaluation with isokinetic strength measurements of both knees. All data were evaluated separately for men and women and compared for each time interval using the Mann-Whitney U test.

RESULTS

Clinical scores improved significantly over the whole study period (p < 0.05). Male patients demonstrated significantly better scores during the follow-up in the KOOS score (p < 0.05). Isokinetic strength measurements after 48 months revealed a significant strength deficit of the treated knee in all test modes compared to the healthy extremity (p < 0.05). Furthermore, male patients achieved significantly higher strength values compared to female patients (p < 0.05).

CONCLUSIONS

ACI is a viable treatment option for full-thickness chondral defects in the knee of both genders. Isokinetic muscle strength measures are significantly worse in women (p < 0.05), but physiological and may play a role for the explanation of gender-specific results after ACI.

Long-term outcomes after first-generation autologous chondrocyte implantation for cartilage defects of the knee

BACKGROUND

Autologous chondrocyte implantation (ACI) represents an established surgical therapy for large cartilage defects of the knee joint. Although various studies report satisfying midterm results, little is known about long-term outcomes.

PURPOSE

To evaluate long-term clinical and magnetic resonance imaging (MRI) outcomes after ACI.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

Between January 1997 and June 2001, a total of 86 patients were treated with ACI for isolated cartilage defects of the knee. The mean patient age at the time of surgery was 33.3 ± 10.2 years, and the mean defect size was 6.5 ± 4.0 cm(2). Thirty-four defects were located on the medial femoral condyle and 13 on the lateral femoral condyle, while 6 patients were treated for cartilage defects of the trochlear groove and 17 for patellar lesions. At a mean follow-up of 10.9 ± 1.1 years, 70 patients (follow-up rate, 82%) treated for 82 full-thickness cartilage defects of the knee were available for an evaluation of knee function using standard instruments, while 59 of these patients were additionally evaluated by 1.5-T MRI to quantify the magnetic resonance observation of cartilage repair tissue (MOCART) score. Clinical function at follow-up was assessed by means of the Lysholm score, the International Knee Documentation Committee (IKDC) score, and the Knee injury and Osteoarthritis Outcome Score (KOOS). Patient activity was assessed by the Tegner score. In addition, pain on a visual analog scale (VAS) and patient satisfaction were evaluated separately.

RESULTS

At follow-up, 77% reported being "satisfied" or "very satisfied." The mean IKDC score at follow-up was 74.0 ± 17.3. The mean Lysholm score improved from 42.0 ± 22.5 before surgery to 71.0 ± 17.4 at follow-up (P < .01). The mean pain score on the VAS decreased from 7.2 ± 1.9 preoperatively to 2.1 ± 2.1 postoperatively. The mean MOCART score was 44.9 ± 23.6. Defect-associated bone marrow edema was found in 78% of the cases. Nevertheless, no correlation between the MOCART score and clinical outcome (IKDC score) could be found (Pearson coefficient, r = 0.173).

CONCLUSION

First-generation ACI leads to satisfying clinical results in terms of patient satisfaction, reduction of pain, and improvement in knee function. Nevertheless, full restoration of knee function cannot be achieved. Although MRI reveals lesions in the majority of the cases and the overall MOCART score seems moderate, this could not be correlated with long-term clinical outcomes.

Microfracture technique versus osteochondral autologous transplantation mosaicplasty in patients with articular chondral lesions of the knee: a prospective randomized trial with long-term follow-up

PURPOSE

To compare long-term functional and radiological outcome following microfracture technique (MF) versus osteochondral autologous transplantation (OAT) mosaicplasty for treating focal chondral lesions of the knee.

METHODS

Twenty-five patients (mean age 32.3 years, SD 7.7) with a full-thickness (International Cartilage Repair Society grade 3 or 4) chondral lesion of the articulating surface of the femur were randomized to either MF (n = 11) or OAT mosaicplasty (n = 14). At a median follow-up of 9.8 years (range 4.9-11.4), the patients were evaluated using Lysholm score (n = 25), Knee Injury and Osteoarthritis Outcome Score (KOOS, n = 25), isokinetic quadriceps measurement and hamstring strength measurement (n = 22) and standing radiographs (n = 23).

RESULTS

There were no significant differences in Lysholm score, KOOS, isokinetic muscle strength or radiographic osteoarthritis between MF-treated patients and OAT mosaicplasty-treated patients at follow-up. Mean Lysholm score at follow-up was 69.7 [95% confidence interval (CI), 55.1-84.4] for the MF group and 62.6 (95% CI, 52.6-72.6) for the OAT mosaicplasty group.

CONCLUSION

At long-term follow-up, there were no significant differences between patients treated with MF and patients treated with OAT mosaicplasty in patient-reported outcomes, muscle strength or radiological outcome.

LEVEL OF EVIDENCE

Therapeutic study, Level II.

A comparison of the responsiveness of 4 commonly used patient-reported outcome instruments at 5 years after matrix-induced autologous chondrocyte implantation

BACKGROUND

Patient-reported outcome (PRO) instruments are employed to assess outcomes after matrix-induced autologous chondrocyte implantation (MACI), although the PRO most responsive to change after surgery remains unknown.

PURPOSE

To compare the responsiveness of 4 commonly used PRO instruments at 5 years after MACI.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

The Knee Injury and Osteoarthritis Outcome Score (KOOS), the Lysholm score, the Tegner activity scale, and the 36-item Short Form Health Survey (SF-36) were administered to 104 patients before and at 5 years after MACI knee surgery. The Self-administered Patient Satisfaction Scale was employed at 5 years to investigate each patient's overall level of satisfaction as well as satisfaction with relieving pain and improving the ability to perform daily activities, partake in recreational activities, and participate in sport. The effect size (ES) and standardized response mean (SRM) were used to compare PRO responsiveness. A receiver operating characteristic (ROC) curve analysis was performed to evaluate the extent to which PRO changes were associated with satisfaction. The minimal clinically important difference (MCID) according to the criterion of patient satisfaction was identified as the PRO instrument change score maximizing classification accuracy.

RESULTS

The most responsive PRO measures were the KOOS sport/recreation (ES, 1.63; SRM, 1.43) and quality of life (QOL) (ES, 1.37; SRM, 1.18) subscales. The least responsive were the SF-36 mental component summary (MCS) (ES, 0.38; SRM, 0.40) and the Tegner activity scale (ES, 0.91; SRM, 0.59). Of the 104 patients, 54 (51.9%) reported being "very satisfied," 38 (36.5%) "somewhat satisfied," 8 (7.7%) "somewhat dissatisfied," and 4 (3.9%) "very dissatisfied." A ROC curve analysis was performed using "very satisfied" as the responder criterion. The strongest association was between the change in KOOS sport/recreation with satisfaction in improving the ability to perform recreational activities (area under the curve, 0.756; 95% confidence interval, 0.663-0.849), and the change score maximizing prediction accuracy (MCID) was 40 (sensitivity, 69%; specificity, 76%).

CONCLUSION

The KOOS sport/recreation and QOL subscales were the most responsive PRO measures and were most predictive of satisfaction. This information will provide a guide as to the improvements required in pertinent PRO measures to produce a satisfied patient, while allowing researchers to better structure trials in these patients using the most relevant PRO instruments.

Continuous passive motion following cartilage surgery: does a common protocol exist?

Continuous passive motion (CPM) devices have the potential to improve the histological content as well as the rate and volume of chondrogenesis in repair tissue following chondral injury. However, clinical evidence is lacking to support broad implementation of CPM following cartilage restoration procedures. We searched PubMed, CINAHL, SPORTDiscus, and Cochrane for such terms as knee, continuous passive motion, CPM, ACI, ACT, autologous chondrocyte implantation, autologous chondrocyte transplantation, microfracture, marrow-stimulation technique, mosaicplasty, osteochondral autograft, and osteochondral allograft. Inclusion criteria were all English-language studies of human subjects, evidence levels I to IV, reporting the use of CPM following cartilage repair or restoration surgery in the knee. One hundred and seven studies met inclusion criteria. Sixty-three studies reported the use of CPM following autologous chondrocyte implantation; 28 reported the use of CPM following microfracture; 13 reported the use of CPM following osteochondral autograft; and 15 reported the use of CPM following osteochondral allograft (several studies reported > 1 type of cartilage procedure, which explains why the sum of all studies reporting a particular procedure [119] is greater than the number of studies included in the review [107]). Of the 5723 patients included, 60.8% were treated with autologous chondrocyte implantation, 23.1% were treated with microfracture, 6.4% were treated with osteochondral autograft, and 9.7% were treated with osteochondral allograft. Of the 6612 total defects, 5043 (76.3%) were tibiofemoral and 1569 (23.7%) were patellofemoral. Most reports of CPM use after cartilage restoration procedures did not include specific information on how it was implemented. Overall, the description of CPM protocols in published knee articular cartilage surgery studies was disappointing. The majority of studies did not describe common variables such as the duration of CPM therapy, the initiation of CPM therapy, and the initial range of motion used. The most commonly prescribed parameters within a CPM regimen are initiated on the first postoperative day, with an initial range-of-motion of 0 to 30 degrees and a frequency of 1 cycle per minute, and for 6 to 8 hours daily over 6 weeks. The lack of consistent standardized reporting of postoperative CPM protocols provides an impetus to researchers and clinicians to more clearly define and describe their use following knee articular surgery.

Generating cartilage repair from pluripotent stem cells

The treatment of degeneration and injury of articular cartilage has been very challenging for scientists and surgeons. As an avascular and hypocellular tissue, cartilage has a very limited capacity for self-repair. Chondrocytes are the only cell type in cartilage, in which they are surrounded by the extracellular matrix that they secrete and assemble. Autologous chondrocyte implantation for cartilage defects has achieved good results, but the limited resources and complexity of the procedure have hindered wider application. Stem cells form an alternative to chondrocytes as a source of chondrogenic cells due to their ability to proliferate extensively while retaining the potential for differentiation. Adult stem cells such as mesenchymal stem cells have been differentiated into chondrocytes, but the limitations in their proliferative ability and the heterogeneous cell population hinder their adoption as a prime alternative source for generating chondrocytes. Human embryonic stem cells (hESCs) are attractive as candidates for cell replacement therapy because of their unlimited self-renewal and ability for differentiation into mesodermal derivatives as well as other lineages. In this review, we focus on current protocols for chondrogenic differentiation of ESCs, in particular the chemically defined culture system developed in our lab that could potentially be adapted for clinical application.

The feasibility of a 3-month active rehabilitation program for patients with knee full-thickness articular cartilage lesions: the Oslo Cartilage Active Rehabilitation and Education Study

STUDY DESIGN

Case series.

OBJECTIVES

To evaluate the feasibility of an active rehabilitation program for patients with knee full-thickness articular cartilage lesions.

BACKGROUND

No studies have yet evaluated the effect of active rehabilitation in patients with knee full-thickness articular cartilage lesions or compared the effects of active rehabilitation to those of surgical interventions. As an initial step, the feasibility of such a program needs to be described.

METHODS

Forty-eight patients with a knee full-thickness articular cartilage lesion and a Lysholm score below 75 participated in a 3-month active rehabilitation program consisting of cardiovascular training, knee and hip progressive resistance training, and neuromuscular training. Feasibility was determined by monitoring adherence to the program, clinical changes in knee function, load progression, and adverse events. Patients were tested before and after completing the rehabilitation program by using patient-reported outcomes (Knee injury and Osteoarthritis Outcome Score, International Knee Documentation Committee Subjective Knee Evaluation Form 2000) and isokinetic muscle strength and hop tests. To monitor adherence, load progression, and adverse events, patients responded to an online survey and kept training diaries.

RESULTS

The average adherence rate to the rehabilitation program was 83%. Four patients (9%) showed adverse events, as they could not perform the exercises due to pain and effusion. Significant and clinically meaningful improvement was found, based on changes on the International Knee Documentation Committee Subjective Knee Evaluation Form 2000, the Knee injury and Osteoarthritis Outcome Score quality of life subscale, isokinetic muscle strength, and hop performance (P<.05), with small to large effect sizes (standardized response mean, 0.3-1.22).

CONCLUSION

The combination of a high adherence rate, clinically meaningful changes, and positive load progression and the occurrence of only a few adverse events support the potential usefulness of this program for patients with knee full-thickness cartilage lesions. This study was registered with the public trial registry ClinicalTrials.gov (NCT00885729).

LEVEL OF EVIDENCE

Therapy, level 4.

Second-generation arthroscopic autologous chondrocyte implantation for the treatment of degenerative cartilage lesions

PURPOSE

Degenerative cartilage lesions present a negative joint environment, which may have a negative effect on the process of cartilage regeneration. The aim of this study is to analyze the clinical outcome obtained with the treatment for isolated degenerative knee cartilage lesions by second-generation arthroscopic autologous chondrocyte implantation (ACI).

METHODS

Fifty-eight consecutive patients affected by focal degenerative chondral lesions of the femoral condyles and trochlea were treated by second-generation arthroscopic ACI. The mean age at surgery was 34.7 ± 9.1 years and the average defect size was 2.3 ± 0.9 cm(2). The patients were prospectively evaluated with IKDC, EQ-VAS, and Tegner scores preoperatively, at 2 and 6 years.

RESULTS

A statistically significant improvement was observed in all scores from the basal evaluation to the final follow-up. The IKDC subjective score improved from 39.3 ± 13.6 to 68.8 ± 22.7 and 68.5 ± 23.9 at the 2- and 6-year follow-ups, respectively, with a significant improvement (P < 0.0005) and stable results over time; the same trend was confirmed by the EQ-VAS and Tegner scores. The worst results were found in patients with a low physical activity level, women, and those having undergone previous surgery, whereas the symptom duration before surgery did not influence the final outcome. The failure rate was 18.5%.

CONCLUSIONS

Despite a significant improvement, the results were lower with respect to the outcome reported in different study populations, and the number of failures was markedly higher, too. Tissue-engineered cartilage implantation is a promising approach for the treatment of degenerative chondral lesions, but graft properties, besides mechanical and biochemical joint environment, have to be improved.

LEVEL OF EVIDENCE

Case series, Level IV.

Isokinetic knee extensor strength deficit following matrix-induced autologous chondrocyte implantation

BACKGROUND

Autologous chondrocyte implantation has become an established technique for addressing knee cartilage defects. Despite reported improvement in pain and regeneration of hyaline-like repair tissue, little has been reported on the recovery of knee strength.

METHODS

Knee strength assessment was undertaken in 60 patients at 5 years following autologous chondrocyte implantation. Using an isokinetic dynamometer, and during isokinetic knee extension and flexion angular velocities of 60°, 90° and 120°/s, the peak torque, torque at 45° of knee flexion and hamstrings/quadriceps ratio was obtained, in both the operated and non-operated limbs. Pain at the time of assessment was obtained. Independent sample t-tests were used to assess differences in the operated and non-operated sides.

FINDINGS

There were no significant differences (p>0.05) between the operated and non-operated legs in the peak knee flexor torque or knee flexor torque at a knee flexion angle of 45°, at all angular velocities (60°, 90° and 120°/s). While the peak knee extensor torque was less in the operated leg at all angular velocities, these differences were not significant (p>0.05). However, a significantly reduced (p<0.05) knee extensor torque at a knee flexion angle of 45°, was observed at all speeds.

INTERPRETATION

While patients had recovered their knee flexor strength, they still demonstrated a reduced knee extensor strength profile at 5 years. This demonstrates that the early supervised rehabilitation phase following autologous chondrocyte implantation is not sufficient to restore long-term knee strength, and ongoing patient advice and rehabilitation is required extending beyond this early period. It is unknown how this prolonged reduction in strength may affect long-term graft outcome.

Matrix-induced autologous chondrocyte implantation (MACI) in the knee

PURPOSE

Matrix-induced autologous chondrocyte implantation (MACI) has been in use for chondral defect repair since 2000, but to date, only little is known about its histological outcomes in the repair of knee cartilage defects. This prospective multicentre study aims to evaluate (1) the quality of the repair tissue obtained from biopsies taken during second-look arthroscopy and (2) the relationship between the histological outcome, the macroscopic appearance of the repair and the patients' functional status.

METHODS

Thirty-three second-look core biopsies from 30 patients treated with MACI were analysed. At the time of biopsy, the surgeon reported the reason for the second-look arthroscopy, the quality of the repair tissue and the patient's functional status on a standardised form. Biopsies together with patient data were sent to our centre to undergo blind histological evaluation and data analysis.

RESULTS

The median overall ICRS II histological score of the examined population was 57 (1st-3rd quartile 41-75). According to the ICRS cartilage repair assessment (CRA) arthroscopic evaluation, 10 biopsies (30%) were classified as normal, 17 (51%) as nearly normal, 4 (12%) as abnormal and 2 (6%) as severely abnormal. The histological outcome was not significantly related either to the macroscopic appearance of the lesion or to the patient's functional status at the time of biopsy.

CONCLUSIONS

In the examined population, the macroscopic appearance of the repair tissue gave an overly favourable impression in comparison with the real histological composition of the tissue, which was possibly still maturing in many cases. The healing process after MACI needs to be better understood through a larger histological study, and a longer follow-up is needed to better clarify the relationship between histology and long-term functional status.

LEVEL OF EVIDENCE

IV.

Cartilage repair in the rabbit knee: mosaic plasty resulted in higher degree of tissue filling but affected subchondral bone more than microfracture technique: a blinded, randomized, controlled, long-term follow-up trial in 88 knees

PURPOSE

Discrepancies and variances in outcome following different surgical techniques for cartilage repair are poorly understood. Successful repair relies on proper tissue filling without initiating degenerative processes in the cartilage-bone unit. Consequently, the objective of the current study was to compare two available techniques for cartilage repair, i.e., microfracture technique and mosaic plasty, regarding tissue filling and subchondral bone changes in an experimental model.

METHODS

A 4-mm pure chondral defect was created in the medial femoral condyle of both knees in New Zealand rabbits, aged 22 weeks. A stereomicroscope was used to optimize the preparation of the defects. In one knee (randomized), the defect was treated with microfracture technique whereas in the other with mosaic plasty. The animals were killed at 12, 24 and 36 weeks after surgery. Defect filling, new bone formation above the level of the tidemark and the density of subchondral mineralized tissue were estimated by histomorphometry.

RESULTS

Mosaic plasty resulted in a significantly 34% higher degree of tissue filling than microfracture technique at 36 weeks, SD of mean difference being 34%. Mosaic plasty resulted in significantly more new bone formation and reduced subchondral mineralized tissue density compared to microfracture technique. The differences between the two techniques were apparent mainly at the long-term follow-up.

CONCLUSION

Tissue filling is a limiting factor regarding microfracture technique when compared to mosaic plasty, whereas mosaic plasty resulted in more bone changes than microfracture technique-the implications of the latter remain to be settled. This study underlines the difficulty in predicting outcome in the single case with any of these two techniques, particularly in a long-term perspective.

Repair of osteochondral lesions in the knee by chondrocyte implantation using the MACI® technique

PURPOSE

Matrix-associated autologous chondrocyte implantation (MACI(®)) is an innovative therapeutic option for the treatment of chondral and osteochondral lesions of the knee.

METHODS

Fifty-three patients (54 knees) with MRI-documented osteochondral lesions were treated with MACI(®). A clinical assessment was performed using VAS score, Lysholm score, and Tegner activity level after an average follow-up of 27 months (SD: 2.3). MRI scans were performed 12 and 24 months after surgery. Seventeen patients were reevaluated after an average time of 59 months (SD: 6.7) after surgery.

RESULTS

Two years after transplantation, Lysholm score increased from a preoperative mean value of 70 (SD: 13.4) to 95 (SD: 6.4); the average VAS score decreased from a preoperative value of 5.2 (SD: 2.9) to 1.9 (SD: 2.1). The difference with respect to Tegner activity level did not prove to be significant. At 1 year, MRI scans documented a completely repaired defect with slight subchondral bone abnormality in 38 cases (70%). Satisfying outcomes were confirmed on 17 patients who were reevaluated 5 years after surgery. At 60 months, MRI scans showed complete integration with the surrounding native cartilage without any sign of detachment or bone marrow edema in 15 cases (88%).

CONCLUSION

The MACI(®) technique is a safe and clinically effective procedure, which has been proven to be valuable in treating osteochondral defects even over the long term.

LEVEL OF EVIDENCE

Therapeutic study, Level III-2 (retrospective cohort study).

Rehabilitation after autologous chondrocyte implantation for isolated cartilage defects of the knee

Autologous chondrocyte implantation for treatment of isolated cartilage defects of the knee has become well established. Although various publications report technical modifications, clinical results, and cell-related issues, little is known about appropriate and optimal rehabilitation after autologous chondrocyte implantation. This article reviews the literature on rehabilitation after autologous chondrocyte implantation and presents a rehabilitation protocol that has been developed considering the best available evidence and has been successfully used for several years in a large number of patients who underwent autologous chondrocyte implantation for cartilage defects of the knee.

Repair of focal cartilage defects with scaffold-assisted autologous chondrocyte grafts: clinical and biomechanical results 48 months after transplantation

BACKGROUND

Scaffold-assisted autologous chondrocyte implantation is a clinically effective procedure for cartilage repair, but biomechanical evaluations are still missing.

PURPOSE

This study was conducted to assess the clinical efficacy, including biomechanical analyses, of BioSeed-C treatment for traumatic and degenerative cartilage defects of the knee.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The authors evaluated the midterm clinical and biomechanical outcome of BioSeed-C, a cell-based fibrin-polymer graft for the treatment of cartilage defects. Clinical outcome at 4-year follow-up was assessed in 52 patients with full-thickness cartilage defects, International Cartilage Repair Society (ICRS) stage III and IV. Clinical scoring was performed preoperatively and 48 months after implantation using the Lysholm score, the International Knee Documentation Committee (IKDC) score, the ICRS score, the Knee injury and Osteoarthritis Outcome Score (KOOS), and the Noyes score. Cartilage regeneration was assessed by magnetic resonance imaging (MRI) using the Henderson-Kreuz score. Biomechanical evaluation was performed by isokinetic strength measurements, comparing healthy and operated knee of each patient.

RESULTS

Clinical evaluation showed significant improvement in the Lysholm (from 51.8 preoperatively to 80.7 at 48 months postoperatively), IKDC (from 47.5 to 71.5), ICRS (from 3.8 to 2.0), KOOS (subcategory pain from 62 to 78, symptoms from 68 to 76, activities of daily living from 68 to 85, sports from 19 to 55, and quality of life from 30 to 55), and Noyes (from 31 to 59) scores (P ≤ .001) 48 months after implantation of BioSeed-C compared with the preoperative situation. The MRI evaluations showed moderate to complete defect filling in 43 of 44 treated patients. Two patients without improvement in the clinical and MRI scores received a total knee endoprosthesis after 4 years. Isokinetic evaluation showed significantly reduced maximum strength capacities for knee flexion and extension at the operated knee compared with the healthy knee (P < .05).

CONCLUSION

The clinical outcomes 4 years after graft implantation are good despite a persisting strength deficit. Implanting BioSeed-C is a promising treatment option for cartilage defects of the knee. More emphasis should be put on the rehabilitation of muscular strength.

The use of continuous passive motion following knee cartilage defect surgery: a systematic review

We evaluated the clinical evidence of using continuous passive motion postoperatively after treating articular cartilage lesions of the knee. We hypothesized that postoperatively, the use of continuous passive motion improves the outcomes of cartilage restoration procedures. Multiple medical databases (MEDLINE, EMBASE, CINAHL, PubMed, Sport-Discus, and Cochrane) were searched for Level I through IV evidence with specific study inclusion and exclusion criteria. The following key words were searched: microfracture, mosaicplasty, OATS, ACI, osteochondral autograft, osteochondral allograft, autologous chondrocyte implantation, autologous chondrocyte transplantation, CPM, continuous passive motion, motion therapy, postoperative knee rehabilitation, cartilage, knee. All studies were independently reviewed by the authors and the references were checked for any missed articles. Four Level III studies were identified that met inclusion criteria for our hypothesis. No randomized, controlled studies were identified. A meta-analysis could not be performed as a result of the heterogeneity of the procedures and outcome measures. Definitive conclusions regarding the benefits of continuous passive motion postoperatively in knee cartilage surgery could not be made secondary to this heterogeneity. Continuous passive motion is commonly used postoperatively following cartilage surgery. Unfortunately, the clinical evidence (only 4 studies) to support the use of continuous passive motion is lacking despite an overwhelming abundance of basic science support and the common clinical practice of continuous passive motion implementation postoperatively in knee cartilage restoration procedures. There is a great need for well-conducted, high-level evidence studies to address this void in our literature.

Knee pain and mobility impairments: meniscal and articular cartilage lesions

The Orthopaedic Section of the American Physical Therapy Association presents this fifth set of clinical practice guidelines on knee pain and mobility impairments, linked to the International Classification of Functioning, Disability, and Health (ICF). The purpose of these practice guidelines is to describe evidence-based orthopaedic physical therapy clinical practice and provide recommendations for (1) examination and diagnostic classification based on body functions and body structures, activity limitations, and participation restrictions, (2) interventions provided by physical therapists, (3) and assessment of outcome for common musculoskeletal disorders.

Application of tissue-engineered cartilage with BMP-7 gene to repair knee joint cartilage injury in rabbits

Injured articular cartilage has a poor capacity for spontaneous healing. So far, satisfactory solution to this subsistent problem has not been found, but transgenic therapy may be a promising way. This study aims to evaluate the effectiveness of a tissue-engineered cartilage that was transfected with morphogenetic protein 7 (BMP 7) in repairing the cartilaginous defects of rabbit knee joints. Chondrocytes were transfected with BMP-7 gene (5 x 10(6) cells/ml), inoculated into the collagen-fibrin gel scaffolds, and cultured for 14 days. Then, the scaffolds were implanted onto the created defects (5.0 mm in diameter) in rabbits' knee joints. After 12 weeks, the rabbits were sacrificed and histological sections were evaluated using modified O'Driscoll cartilage scores; In situ hybridization and immunohistochemistry were performed to detect the expression of BMP-7 mRNA and BMP-7 at the implanted site while the content of DNA and GAG was determined as well. A better quality of repairs was observed at the 12th week after implantation when compared to the control group using histological analyses. The content of DNA and specific secretion of GAG in the treatment group is statistically significant different compared with the control group. Gene therapy may be a promising treatment method, but the novel therapy approach needs further studies with respect to a longer follow-up period.

Focal cartilage defects in the knee impair quality of life as much as severe osteoarthritis: a comparison of knee injury and osteoarthritis outcome score in 4 patient categories scheduled for knee surgery

BACKGROUND

Patients with focal cartilage defects in the knee may suffer from both pain and functional impairment. Treatment options are often insufficient. It is not known, however, to what extent their complaints affect quality of life, compared with other knee disorders. Knee Injury and Osteoarthritis Outcome Score (KOOS) is a validated global knee score suitable for comparison of patients with knee complaints attributable to different causes. Hypothesis Complaints because of localized cartilage defects in the knee reduce quality of life measured by KOOS to a different extent than those due to anterior cruciate ligament deficiency and osteoarthritis, when comparing patients within the working population scheduled for surgery.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3. Methods Previously registered KOOS baseline data on patients enrolled in different knee treatment studies were included in the present study; the patients were 18 to 67 years of age (working population) at data registration. The different patient categories were (1) patients with knee osteoarthritis enrolled for knee arthroplasty, (2) patients with knee osteoarthritis enrolled for osteotomies around the knee, (3) patients with focal cartilage lesions enrolled for cartilage repair, and (4) patients with anterior cruciate ligament-deficient knees enrolled for anterior cruciate ligament reconstruction. The KOOS subscale quality of life was the main parameter for comparison of complaints.

RESULTS

At preoperative baseline, patients with focal cartilage defects in the knee scored 27.5 on the KOOS subscale quality of life, not significantly different from the 28.8 and 27.2 in the patients with osteoarthritis enrolled for knee osteotomies and arthroplasties, respectively. For all the subscales of KOOS, the cartilage patients scored significantly lower than the patients with anterior cruciate ligament deficiency.

CONCLUSION

Patients with focal cartilage lesions have major problems with pain and functional impairment. Their complaints are worse than those of patients with anterior cruciate ligament-deficient knees, and quality of life is affected to the same extent as in patients scheduled for knee replacement.