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

Dextran-tryamine hydrogel maintains position and integrity under simulated loading in a human cadaver knee model

Objective

This dextran-tyramine hydrogel is a novel cartilage repair technique, filling focal cartilage defects to provide a cell-free scaffold for subsequent cartilage repair. We aim to asses this techniques' operative feasibility in the knee joint and its ability to maintain position and integrity under expected loading conditions.

Method

Seven fresh-frozen human cadaver legs (age range 55-88) were used to create 30 cartilage defects on the medial and lateral femoral condyles dependent of cartilage quality, starting with 1.0 ​cm2; augmenting to 1.5 ​cm2 and eventually 2.0 ​cm2. The defects were operatively filled with the injectable hydrogel scaffold. The knees were subsequently placed on a continues passive motion machine for 30 ​min of non-load bearing movement, mimicking post-operative rehabilitation. High resolution digital photographs documented the hydrogel scaffold after placement and directly after movement. Three independent observers blinded for the moment compared the photographs on outline attachment, area coverage and hydrogel integrity.

Results

The operative procedure was uncomplicated in all defects, application of the hydrogel was straightforward and comparable to common cartilage repair techniques. No macroscopic iatrogenic damage was observed. The hydrogel scaffold remained predominately unchanged after non-load bearing movement. Outline attachment, area coverage and hydrogel integrity were unaffected in 87%, 93% and 83% of defects respectively. Larger defects appear to be more affected than smaller defects, although not statistically significant (p ​> ​0.05).

Conclusion

The results of this study show operative feasibility of this cell-free hydrogel scaffold for chondral defects of the knee joint. Sustained outline attachment, area coverage and hydrogel integrity were observed after non-load bearing knee movement.

Follow-up Treatment after Cartilage Therapy of the Knee Joint - a Recommendation of the DGOU Clinical Tissue Regeneration Working Group

The first follow-up treatment recommendation from the DGOU's Clinical Tissue Regeneration working group dates back to 2012. New scientific evidence and changed framework conditions made it necessary to update the follow-up treatment recommendations after cartilage therapy.As part of a multi-stage member survey, a consensus was reached which, together with the scientific evidence, provides the basis for the present follow-up treatment recommendation.The decisive criterion for follow-up treatment is still the defect localisation. A distinction is made between femorotibial and patellofemoral defects. In addition, further criteria regarding cartilage defects are now also taken into account (stable cartilage edge, location outside the main stress zone) and the different methods of cartilage therapy (e. g. osteochondral transplantation, minced cartilage) are discussed.The present updated recommendation includes different aspects of follow-up treatment, starting with early perioperative management through to sports clearance and resumption of contact sports after cartilage therapy has taken place.

Quadriceps Dysfunction Following Joint Preservation Surgery: A Review of the Pathophysiologic Basis and Mitigation Strategies

PURPOSE OF REVIEW

To characterize quadriceps muscle dysfunction associated with knee joint preservation surgery, with a focus on its pathophysiology and promising approaches to mitigate its impact on clinical outcomes.

RECENT FINDINGS

Quadriceps dysfunction (QD) associated with knee joint preservation surgery results from a complex interplay of signaling, related to changes within the joint and from those involving the overlying muscular envelope. Despite intensive rehabilitation regimens, QD may persist for many months postoperatively and negatively impact clinical outcomes associated with various surgical procedures. These facts underscore the need for continued investigation into the potential detrimental effects of regional anesthetic and intraoperative tourniquet use on postoperative quadriceps function, with an outward focus on innovation within the field of postoperative rehabilitation. Neuromuscular stimulation, nutritional supplementation, cryotherapy, blood flow restriction (BFR), and open-chain exercises are all potential additions to postoperative regimens. There is compelling literature to suggest that these modalities are efficacious and may diminish the magnitude and duration of postoperative QD. A clear understanding of QD, with respect to its pathophysiology, should guide perioperative treatment and rehabilitation strategies and influence ongoing rehabilitation-based research and innovation. Moreover, clinicians must appreciate the magnitude of QD's effect on diminished clinical outcomes, risk for re-injury and patients' ability (or inability) to return to pre-injury level of activity following knee joint preservation procedures.

Berberine encapsulated in exosomes derived from platelet-rich plasma promotes chondrogenic differentiation of the Bone Marrow Mesenchymal Stem Cells via the Wnt/β-catenin pathway

Cartilage regenerative medicine, wherein the stem cells from adults exert a crucial role, has high potential in the treatment of defective articular cartilage. Recently, Bone marrow mesenchymal stem cells (BMSCs) are being increasingly recognized as an alternative source of adult stem cells, which are capable of differentiating into several cell types (e.g., adipocytes, chondrocytes, and osteoblasts). However, their proliferative properties and tendency to dedifferentiate restrict their use in clinical settings. Recently, a possible bioactive material PRP-exos (exosomes derived from platelet-rich plasma), has emerged, which can effectively facilitate the differentiation and proliferation of cells. Recent studies have reported that berberine (Ber), known to have anti-inflammatory properties, plays a role in osteogenesis. Since biological molecules are used in combinations, we attempted to assess the effect of Exos-Ber (PRP-exos in combination with Ber) on the chondrogenic differentiation of BMSCs in vitro. In this study, Exos-Ber was observed to promote the proliferation of BMSCs and cause their chondrogenic differentiation in vitro. Additionally, Exos-Ber could promote the migration of BMSCs and increase the protein expression of the chondrogenic genes (Collagen II, SOX9, Aggrecan). After treatment with Exos-Ber, significant induction of β-catenin expression was observed, which could be repressed successfully by adding β-catenin inhibitor XAV-939. Interestingly, the repression of the Wnt/β-catenin axis also resulted in reduced gene expression levels of Collagen II, SOX9, and Aggrecan. These observations indicated that Exos-Ber facilitated the differentiation of chondrogenic BMSCs by modulating the Wnt/β-catenin axis, which offers innovative insights into the reconstruction of cartilage.

Rehabilitation Variability Following Osteochondral Autograft and Allograft Transplantation of the Knee

OBJECTIVE

The aim of this study is to assess the variability of postoperative rehabilitation protocols used by orthopedic surgery residency programs for osteochondral autograft transplantation (OAT) and osteochondral allograft transplantation (OCA) of the knee.

DESIGN

Online postoperative OAT and OCA rehabilitation protocols from US orthopedic programs and the scientific literature were reviewed. A custom scoring rubric was developed to analyze each protocol for the presence of discrete rehabilitation modalities and the timing of each intervention.

RESULTS

A total of 16 programs (10.3%) from 155 US academic orthopedic programs published online protocols and a total of 35 protocols were analyzed. Twenty-one protocols (88%) recommended immediate postoperative bracing following OAT and 17 protocols (100%) recommended immediate postoperative bracing following OCA. The average time protocols permitted weight-bearing as tolerated (WBAT) was 5.2 weeks (range = 0-8 weeks) following OAT and 6.2 weeks (range = 0-8 weeks) following OCA. There was considerable variation in the inclusion and timing of strength, proprioception, agility, and pivoting exercises. Following OAT, 2 protocols (8%) recommended functional testing as criteria for return to sport at an average time of 12.0 weeks (range = 12-24 weeks). Following OCA, 1 protocol (6%) recommended functional testing as criteria for return to sport at an average time of 12.0 weeks (range = 12-24 weeks).

CONCLUSION

A minority of US academic orthopedic programs publish OAT and OCA rehabilitation protocols online. Among the protocols currently available, there is significant variability in the inclusion of specific rehabilitation components and timing of many modalities. Evidence-based standardization of elements of postoperative rehabilitation may help improve patient care and subsequent outcomes.

Timing of postoperative weightbearing in the treatment of traumatic chondral injuries of the knee in athletes - A systematic review of current concepts in clinical practice

BACKGROUND

Surgery aims to stimulate healing and enable a safe return to sport in athletes with symptomatic cartilage lesions of the knee. Timing of postoperative weightbearing is crucial, balancing a stimulation of the healing and avoiding reinjury.To explore current concepts of timing to partial and full weightbearing and rate of return to sport in athletes after articular cartilage surgery of the knee.Systematic Review of studies with level of evidence I-III.

METHODS

Four databases (Pubmed, Web of Science, Scopus and Embase) were searched using a predetermined keyword strategy. Two independent reviewers screened results according to inclusion and exclusion criteria. Modified Coleman Methodology Score (mCMS) was used for the quality assessment.

RESULTS

5294 records were found. Data from ten studies was extracted after duplicate removal, title and abstract screening and full-text evaluation. Eight of the ten studies included a detailed rehabilitation protocol, including 336 out of a total athletic population of 401. 62% began partial weightbearing (PWB) 1-2 weeks postoperatively, while 38% began within 3-4 weeks. The studies that had a later PWB all returned to full weightbearing (FWB) within 6-8 weeks. One study with early PWB returned to early FWB, while the other two returned 10-12 weeks postoperatively. "Return to Sport" (RTS) was the most common reported outcome measure, with most studies reporting RTS at 80% or higher.

CONCLUSION

There is no clear evidence that the timing of weightbearing (WB) affects the outcome and return to sport in athletes after surgery for focal full-thickness cartilage lesions of the knee. On the other hand, there seems to be no adverse effects in adopting an early WB strategy, currently defined differently by different authors. Further studies directly comparing the timing of WB for specific surgical procedures in athletes and with relevant control groups is recommended. There is a need for a consensus in regard to more exactly defining "early" vs "late" weightbearing in relation to a universal and precisely defined state of healing.

Rehabilitation Variability Following Femoral Condyle and Patellofemoral Microfracture Surgery of the Knee

OBJECTIVE

To assess the variability of postoperative rehabilitation protocols used by orthopedic surgery residency programs for microfracture of femoral condyle and patellofemoral lesions of the knee.

DESIGN

Online postoperative microfracture rehabilitation protocols from US orthopedic programs and the scientific literature were reviewed. A custom scoring rubric was developed to analyze each protocol for the presence of discrete rehabilitation modalities and the timing of each intervention.

RESULTS

A total of 18 programs (11.6%) from 155 US academic orthopedic programs' published online protocols and a total of 44 protocols were analyzed. Seventeen protocols (56.7%) recommended immediate postoperative bracing for femoral condyle lesions and 17 (89.5%) recommended immediate postoperative bracing for patellofemoral lesions. The average time to permitting weight-bearing as tolerated (WBAT) was 6.1 weeks (range, 0-8) for femoral condyle lesions and 3.7 weeks (range, 0-8 weeks) for patellofemoral lesions. There was considerable variation in the inclusion and timing of strength, proprioception, agility, and pivoting exercises. For femoral condyle lesions, 10 protocols (33.3%) recommended functional testing prior to return to sport at an average of 23.3 weeks postoperatively (range, 12-32 weeks). For patellofemoral lesions, 4 protocols (20.0%) recommended functional testing for return to sport at an average of 21.0 weeks postoperatively (range, 12-32 weeks).

CONCLUSION

A minority of US academic orthopedic programs publish microfracture rehabilitation protocols online. Among the protocols currently available, there is significant variability in the inclusion of specific rehabilitation components and timing of many modalities. Evidence-based standardization of elements of postoperative rehabilitation may help improve patient care and subsequent outcomes.

A Comparison of Neuromuscular Electrical Stimulation Parameters for Postoperative Quadriceps Strength in Patients After Knee Surgery: A Systematic Review

CONTEXT

Postoperative quadriceps strength weakness after knee surgery is a persistent issue patients and health care providers encounter.

OBJECTIVE

To investigate the effect of neuromuscular electrical stimulation (NMES) parameters on quadriceps strength after knee surgery.

DATA SOURCES

CINAHL, MEDLINE, SPORTDiscus, and PubMed were systematically searched in December 2018.

STUDY SELECTION

Studies were excluded if they did not assess quadriceps strength or if they failed to report the NMES parameters or quadriceps strength values. Additionally, studies that applied NMES to numerous muscle groups or simultaneously with other modalities/treatments were excluded. Study quality was assessed with the Physiotherapy Evidence Database (PEDro) scale for randomized controlled trials.

STUDY DESIGN

Systematic review.

LEVEL OF EVIDENCE

Level 1.

DATA EXTRACTION

Treatment parameters for each NMES treatment was extracted for comparison. Quadriceps strength means and standard deviations were extracted and utilized to calculate Hedge g effect sizes with 95% CIs.

RESULTS

Eight RCTs were included with an average Physiotherapy Evidence Database scale score of 5 ± 2. Hedge g effect sizes ranged from small (-0.37; 95% CI, -1.00 to 0.25) to large (1.13; 95% CI, 0.49 to 1.77). Based on the Strength of Recommendation Taxonomy Quality of Evidence table, the majority of the studies included were low quality RCTs categorized as level 2: limited quality patient-oriented evidence.

CONCLUSION

Because of inconsistent evidence among studies, grade B evidence exists to support the use of NMES to aid in the recovery of quadriceps strength after knee surgery. Based on the parameters utilized by studies demonstrating optimal treatment effects, it is recommended to implement NMES treatment during the first 2 postoperative weeks at a frequency of ≥50 Hz, at maximum tolerable intensity, with a biphasic current, with large electrodes and a duty cycle ratio of 1:2 to 1:3 (2- to 3-second ramp).

Autologous chondrocyte implantation in the knee: systematic review and economic evaluation

BACKGROUND

The surfaces of the bones in the knee are covered with articular cartilage, a rubber-like substance that is very smooth, allowing frictionless movement in the joint and acting as a shock absorber. The cells that form the cartilage are called chondrocytes. Natural cartilage is called hyaline cartilage. Articular cartilage has very little capacity for self-repair, so damage may be permanent. Various methods have been used to try to repair cartilage. Autologous chondrocyte implantation (ACI) involves laboratory culture of cartilage-producing cells from the knee and then implanting them into the chondral defect.

OBJECTIVE

To assess the clinical effectiveness and cost-effectiveness of ACI in chondral defects in the knee, compared with microfracture (MF).

DATA SOURCES

A broad search was done in MEDLINE, EMBASE, The Cochrane Library, NHS Economic Evaluation Database and Web of Science, for studies published since the last Health Technology Assessment review.

REVIEW METHODS

Systematic review of recent reviews, trials, long-term observational studies and economic evaluations of the use of ACI and MF for repairing symptomatic articular cartilage defects of the knee. A new economic model was constructed. Submissions from two manufacturers and the ACTIVE (Autologous Chondrocyte Transplantation/Implantation Versus Existing Treatment) trial group were reviewed. Survival analysis was based on long-term observational studies.

RESULTS

Four randomised controlled trials (RCTs) published since the last appraisal provided evidence on the efficacy of ACI. The SUMMIT (Superiority of Matrix-induced autologous chondrocyte implant versus Microfracture for Treatment of symptomatic articular cartilage defects) trial compared matrix-applied chondrocyte implantation (MACI^®) against MF. The TIG/ACT/01/2000 (TIG/ACT) trial compared ACI with characterised chondrocytes against MF. The ACTIVE trial compared several forms of ACI against standard treatments, mainly MF. In the SUMMIT trial, improvements in knee injury and osteoarthritis outcome scores (KOOSs), and the proportion of responders, were greater in the MACI group than in the MF group. In the TIG/ACT trial there was improvement in the KOOS at 60 months, but no difference between ACI and MF overall. Patients with onset of symptoms < 3 years' duration did better with ACI. Results from ACTIVE have not yet been published. Survival analysis suggests that long-term results are better with ACI than with MF. Economic modelling suggested that ACI was cost-effective compared with MF across a range of scenarios.

LIMITATIONS

The main limitation is the lack of RCT data beyond 5 years of follow-up. A second is that the techniques of ACI are evolving, so long-term data come from trials using forms of ACI that are now superseded. In the modelling, we therefore assumed that durability of cartilage repair as seen in studies of older forms of ACI could be applied in modelling of newer forms. A third is that the high list prices of chondrocytes are reduced by confidential discounting. The main research needs are for longer-term follow-up and for trials of the next generation of ACI.

CONCLUSIONS

The evidence base for ACI has improved since the last appraisal by the National Institute for Health and Care Excellence. In most analyses, the incremental cost-effectiveness ratios for ACI compared with MF appear to be within a range usually considered acceptable. Research is needed into long-term results of new forms of ACI.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42014013083.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Comparative efficacy of cartilage repair procedures in the knee: a network meta-analysis

PURPOSE

While numerous randomized controlled trials have compared surgical treatments for cartilage defects of the knee, the comparative efficacy of these treatments is still poorly understood. The goal of this network meta-analysis was to synthesize these randomized data into a comprehensive model allowing pairwise comparisons of all treatment options and treatment rankings based on multiple measures of efficacy. We hypothesized that advanced chondral procedures would have improved outcomes when compared to microfracture.

METHODS

The MEDLINE, COCHRANE and EMBASE databases were searched systematically up to January 2015. The primary outcome was re-operation measured at 2, 5 and 10 years. Secondary outcomes included Tegner and Lysholm scores, the presence of hyaline cartilage on post-operative biopsy and graft hypertrophy. A random-effects network meta-analysis was performed, and the results are presented as odds ratios and mean differences with 95 % CIs. We ranked the comparative effects of all treatments with surface under the cumulative ranking probabilities.

RESULTS

Nineteen RCT from 15 separate cohorts including 855 patients were eligible for inclusion. No differences were seen in re-operation rates at 2 years. At 5 years osteochondral autografts (OC Auto) had a lower re-operation rate than microfracture (OR 0.03, 95 % CI 0.00-0.49), and at 10 years OC Auto had a lower re-operation rate than microfracture (OR 0.34, 95 % CI 0.12-0.92), but a higher re-operation rate than second-generation ACI (OR 5.81, 95 % CI 2.33-14.47). No significant differences in Tegner or Lysholm scores were seen at 2 years. Functional outcome data at 5 and 10 years were not available. Hyaline repair tissue was more common with OC Auto (OR 16.13, 95 % CI 2.80-92.91) and 2nd generation ACI (OR 7.69, 95 % CI 1.17-50) than microfracture, though the clinical significance of this is unknown. Second-generation ACI (OR 0.12, 95 % CI 0.02-0.59) and MACI (OR 0.13, 95 % CI 0.03-0.59) had significantly lower rates of graft hypertrophy than first-generation ACI. Second-generation ACI, OC Auto and MACI were the highest ranked treatments (in order) when all outcome measures were included.

CONCLUSIONS

Microfracture and advanced cartilage repair techniques have similar re-operation rates and functional outcomes at 2 years. However, advanced repair techniques provide higher-quality repair tissue and might afford lower re-operation rates at 5 and 10 years.

LEVEL OF EVIDENCE

Meta-analysis studies, Level I.

Quantifying Quadriceps Muscle Strength in Patients With ACL Injury, Focal Cartilage Lesions, and Degenerative Meniscus Tears: Differences and Clinical Implications

Background:

Reduced quadriceps strength influences knee function and increases the risk of knee osteoarthritis. Thus, it is of significant clinical relevance to precisely quantify strength deficits in patients with knee injuries.

Purpose:

To evaluate isokinetic concentric quadriceps muscle strength torque values, assessed both from peak torque and at specific knee flexion joint angles, in patients with anterior cruciate ligament (ACL) injury, focal cartilage lesions, and degenerative meniscus tears.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Data were synthesized from patients included in 3 previously conducted research projects: 2 prospective cohort studies and 1 randomized controlled trial. At the time of inclusion, all patients were candidates for surgery. Isokinetic concentric quadriceps muscle strength measurements (60 deg/s) were performed at baseline (preoperative status) and after a period of progressive supervised exercise therapy (length of rehabilitation period: 5 weeks for ACL injury, 12 weeks for cartilage lesions and degenerative meniscus). Outcome measures were peak torque and torque at specific knee flexion joint angles from 20° to 70°. All patients had unilateral injuries, and side-to-side deficits were calculated. For comparisons between and within groups, we utilized 1-way analysis of variance and paired t tests, respectively.

Results:

In total, 250 patients were included. At baseline, cartilage patients had the most severe deficit (39.7% ± 24.3%; P < .001). Corresponding numbers for ACL and degenerative meniscus subjects were 21.7% (±13.2%) and 20.7% (±16.3%), respectively. At retest, there was significant improvement in all groups (P < .001), with remaining deficits of 24.7% (±18.5%) for cartilage, 16.8% (±13.9%) for ACL, and 3.3% (±17.8%) for degenerative meniscus. Peak torque was consistently measured at 60° of knee flexion, whereas the largest mean deficits were measured at 30° at baseline and 70° at retest for the ACL group, at 70° at baseline and retest for the degenerative meniscus group, and at 60° at baseline and at 50° at retest for the cartilage group.

Conclusion:

This study underlines the importance of including torque at specific knee flexion joint angles from isokinetic assessments to identify the most severe quadriceps muscle strength deficits. Furthermore, it confirms the importance of progressive exercise therapy interventions before potential surgery in patients with knee injuries.

How do leg press exercises comply with limited weight bearing?

OBJECTIVES

To investigate foot loadings in different leg press settings with respect to a possible graduation of weight bearing (WB).

DESIGN

Case series.

SETTINGS

Assessing plantar force values by means of dynamic pedobarography taken place in orthopaedic departments' rehab center.

PARTICIPANTS

15 healthy students (9 men and 6 women, age 23 ± 2, weight 75 ± 6 kg) were recruited as participants from the medical faculty.

MAIN OUTCOME MEASURES

Peak force values from normal gait (referred to as 100%) and single and double leg presses (SLP, DLP) with resistances of 10 kg, 20 kg and 40 kg, obtained with pedobarographic insoles.

RESULTS

Performing DLP produced foot loadings (N) of 37 ± 15 with 10 kg, 91 ± 29 with 20 kg and 203 ± 27 with 40 kg, equal to 5%, 12% and 26% of full WB. SLP result in force values of 195 ± 32 with 10 kg, 308 ± 34 with 20 kg and 516 ± 45 with 40 kg, corresponding to 25%, 40% and 67% baseline.

CONCLUSIONS

Leg press exercises can be performed in accordance with a given limitation of foot loading. Above mentioned conditions allow a graduation from 5% to 67% of full WB.

Knee cartilage defect: marrow stimulating techniques

Painful chondral defects of the knee are very difficult problems. The incidence of these lesions in the general population is not known since there is likely a high rate of asymptomatic lesions. The rate of lesions found during arthroscopic exam is highly variable, with reports ranging from 11 to 72 % Aroen (Aroen Am J Sports Med 32: 211-5, 2004); Curl(Arthroscopy13: 456-60, 1997); Figueroa(Arthroscopy 23(3):312-5, 2007;); Hjelle(Arthroscopy 18: 730-4, 2002). Examples of current attempts at cartilage restoration include marrow stimulating techniques, ostochondral autografts, osteochondral allografts, and autologous chondrocyte transplantation. Current research in marrow stimulating techniques has been focused on enhancing and guiding the biology of microfracture and other traditional techniques. Modern advances in stem cell biology and biotechnology have provided many avenues for exploration. The purpose of this work is to review current techniques in marrow stimulating techniques as it relates to chondral damage of the knee.

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.

Self-reported knee function can identify athletes who fail return-to-activity criteria up to 1 year after anterior cruciate ligament reconstruction: a delaware-oslo ACL cohort study

STUDY DESIGN

Cohort study, cross-sectional.

OBJECTIVES

To determine if self-reported knee function assessed with the International Knee Documentation Committee 2000 Subjective Knee Form (IKDC 2000) could discriminate between successful and nonsuccessful performance on return-to-activity criteria (RTAC) tests after anterior cruciate ligament (ACL) reconstruction.

BACKGROUND

Selecting appropriate performance-based and patient-reported tests that can detect side-to-side asymmetries, assess global knee function, and determine a participant's readiness to return to activity after ACL reconstruction can be a challenge for rehabilitation specialists. A simple tool or questionnaire to identify athletes with neuromuscular impairments or activity limitations could provide rehabilitation specialists with crucial data pertinent to their patients' current knee function and readiness to return to higher-level activities.

METHODS

One hundred ninety-four level I and level II athletes who underwent ACL reconstruction participated in the study. One hundred fifty-eight athletes at 6 months after ACL reconstruction and 141 of the athletes at 12 months after ACL reconstruction completed a battery of functional tests to determine readiness to return to activity and the IKDC 2000 to determine self-reported knee function. For each athlete, status on the RTAC test battery was dichotomized into "passed" or "failed," and status on the IKDC 2000 scores was dichotomized into "within" or "below" age- and sex-matched normal ranges. Comparisons were made between status on the RTAC test battery and the IKDC 2000 using chi-square tests. Accuracy statistics were also calculated.

RESULTS

Six months after ACL reconstruction, 112 athletes (70.9%) failed RTAC and 76 (48.1%) were classified as having self-reported knee function below normal ranges. Among the 76 participants with IKDC 2000 scores below normal ranges, 69 (90.8%) failed the RTAC test battery (P<.001). However, among the 82 participants whose IKDC 2000 scores were within normal limits at 6 months, only 39 (47.6%) passed the RTAC test battery (P = .74). Twelve months after ACL reconstruction, 67 athletes (47.5%) failed RTAC and 31 (22.0%) had knee function below normal ranges. Among the 31 participants with IKDC 2000 scores below normal ranges, 25 (80.6%) failed the RTAC test battery (P<.001). However, among the 110 participants whose IKDC 2000 scores were within normal limits at 12 months, only 68 (61.8%) passed the RTAC test battery (P = .017).

CONCLUSION

The IKDC 2000 may be a clinically relevant tool to determine the timeliness or necessity of RTAC testing. For scores obtained 6 and 12 months after ACL reconstruction, low IKDC 2000 scores were reasonably indicative of failure on the RTAC test battery, whereas normal IKDC 2000 scores were not predictive of passing scores on the RTAC test battery.