Reliability, validity, and responsiveness of four knee outcome scales for athletic patients

Knee function and pain related to psychological variables in patients with long-term patellofemoral pain syndrome

STUDY DESIGN

Nonexperimental, descriptive study, including 2 independent samples.

OBJECTIVES

To assess the levels of mental distress and self-perceived health in subjects with long-term patellofemoral pain syndrome (PFPS) compared to a group of healthy subjects, and the relationship between knee function and knee pain to these psychological variables.

BACKGROUND

Psychological variables and those describing self-perceived health status have been given little focus in PFPS research.

METHODS AND MEASURES

One group of 25 men and women between 19 and 44 years of age with unilateral long lasting PFPS, and a control group (n = 23) of healthy subjects (age range, 18-44 years) participated in the study. Knee function was assessed with the use of the Cincinnati Knee Rating System (CKRS) and the triple jump test, and knee pain was measured by a visual analogue scale (VAS). Self-perceived health and mental distress were assessed with the Coop-Wonca Chart and the Hopkins Symptoms Checklist-25 (HSCL-25) questionnaire.

RESULTS

The mean (+/- SD) score on the Coop-Wonca Chart was 2.02 +/- 0.73 in the PFPS group, compared to 1.20 +/- 0.53 in the controls (P < .001). HSCL-25 mean (+/- SD) scores were 1.46 +/- 0.47 and 1.08 +/- 0.18 (P < .001) for the PFPS and the control group, respectively. When analyzed with correlation statistics, CKRS and VAS scores were found to correlate to those of the Coop-Wonca Chart and HSCL-25 scores.

CONCLUSION

Levels of mental distress were higher in the group with PFPS than in the control group, while levels of self-perceived health were lower. Our data indicate that the levels of knee pain and knee function correlate closely to the degree of mental distress and self-perceived health in individuals with PFPS.

Weight Discrimination After Anterior Cruciate Ligament Injury: A Pilot Study

OBJECTIVE

To determine whether the ability to discriminate weights remained accurate after anterior cruciate ligament (ACL) injury.

DESIGN

Descriptive case series.

SETTING

Outpatient physical therapy.

PARTICIPANTS

Convenience sample of 10 participants with unilateral ACL injuries (age, 27.1+/-8.2 y) and 8 healthy controls (age, 22.6+/-2.8 y).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Weber fractions, expressed as percentage differences from the standard weight (3.00 kg) that could be reliably detected (75% correct level), were derived from each leg to provide an index of proprioceptive acuity for weight discrimination. Subjective ratings of knee function (Activities of Daily Living Scale of the Knee Outcome Survey) and measurements of quadriceps strength (peak isometric torque).

RESULTS

The ACL group exhibited a reduced acuity to detect differences in weight on the injured, as compared with the uninjured, side as reflected in the increase in Weber fractions (mean, 6.7%+/-2.3% vs 4.8%+/-1.1%, respectively; P = .043). No such difference in acuity between legs was detected in healthy controls (mean right and left, 5.4%+/-1.4% vs 5.7%+/-1.3%, respectively, P = .99).

CONCLUSIONS

Proprioceptive acuity for weight discrimination was significantly reduced after an ACL injury, possibly reflecting deficits in the ability to properly calibrate force signals generated while muscles are actively contracting, as a result of a loss in ligamentous sensory innervation.

Quadriceps strength and the time course of functional recovery after total knee arthroplasty

STUDY DESIGN

Prospective study with repeated measures.

OBJECTIVES

The overall goal of this investigation was to describe the time course of recovery of impairments and function after total knee arthroplasty (TKA), as well as to provide direction for rehabilitation efforts. We hypothesized that quadriceps strength would be more strongly correlated with functional performance than knee flexion range of motion (ROM) or pain at all time periods studied before and after TKA.

BACKGROUND

TKA is a very common surgery, but very little is known regarding the influence of impairments on functional limitations in this population.

METHODS AND MEASURES

Forty subjects who underwent unilateral TKA followed by rehabilitation, including 6 weeks of outpatient physical therapy, were studied. Testing occurred at 5 time periods: preoperatively, and at 1, 2, 3, and 6 months after surgery. Test measures included quadriceps strength, knee ROM, timed up-and-go test, timed stair-climbing test, bodily pain, and general health and knee function questionnaires.

RESULTS

Subjects experienced significant worsening of knee ROM, quadriceps strength, and performance on functional tests 1 month after surgery. Quadriceps strength went through the greatest decline of all the physical measures assessed and never matched the strength of the uninvolved limb. All measures underwent significant improvements following the 1-month test. Quadriceps strength was the most highly correlated measure associated with functional performance at all testing sessions.

CONCLUSIONS

Functional measures underwent an expected decline early after TKA, but recovery was more rapid than anticipated and long-term outcomes were better than previously reported in the literature. The high correlation between quadriceps strength and functional performance suggests that improved postoperative quadriceps strengthening could be important to enhance the potential benefits of TKA.

A modular prosthesis for patellofemoral arthroplasty: design and initial results

This study was designed to determine if a new and modular prosthesis for patellofemoral arthroplasty would produce results at least as good as those reported for other designs, while simultaneously eliminating the risks of patellar revision should total knee arthroplasty be needed in the future. Another issue was its suitability for the older patient with isolated patellofemoral arthritis in order to avoid destruction of the normal femoro-tibial compartments involved in total knee arthroplasty. Finally, I sought information about the safety and longevity of this prosthesis when used for patellofemoral arthroplasty in severely disabled patients too young to be considered for total knee replacement. From a cohort of 16 patients (8 studied retrospectively and 8 prospectively), aged 26 to 81 years, and followed up for 2.75-6.25 years, 15 (94%) rated their results excellent or good using the Activities of Daily Living Scale. These results are better than previously reported for other prosthetic designs. To date, no patient in this study group has required conversion to a total knee arthroplasty. The design has proven safe for use in both the older and younger patient, but longer followup will be needed to assess greater longevity.

LEVEL OF EVIDENCE

Therapeutic Study, Level IV-8 (case series--no, or historical control group). See the Guidelines for Authors for a complete description of levels of evidence.

Outcome instruments for patellofemoral arthroplasty

Although there are numerous patient outcome instruments available, the most reliable and valid instruments for evaluating patient outcomes after patellofemoral arthroplasty have not been identified. In this article, we review and evaluate the psychometric properties and practical considerations of administering general health instruments (Medical Outcomes Study (MOS) Short Form-36 and Short Form-12), knee scales (Knee Society Clinical Rating System, Knee Outcome Survey, International Knee Documentation Committee form, Knee Injury and Osteoarthritis Outcome Score) and a disease specific scale (Western Ontario and McMaster Universities Osteoarthritis Index) for patellofemoral arthroplasty outcome assessment. Based on our review of the literature, we recommend the Short Form-36 and Knee Injury and Osteoarthritis Outcome Score for evaluation of patellofemoral arthroplasty outcomes and provide recommendations for implementation of these instruments in a clinical setting.

Early results with a total patellofemoral joint replacement arthroplasty prosthesis

This report concerns a new prosthesis for total patellofemoral joint replacement. Patients severely disabled due to isolated patellofemoral arthritis in whom all other treatment options had been tried and failed, or were not indicated, became candidates for this surgery. Fifteen patients met these criteria and were followed an average of 3.75 years (range: 2.25-5.5 years). Using the Activities of Daily Living Scale, 14 of 15 patients (93%) had excellent (85%-100%) or good (75%-84%) results, and 1 was fair (65%-74%).

Control of frontal plane knee laxity during gait in patients with medial compartment knee osteoarthritis

OBJECTIVE

Patients with medial compartment knee osteoarthritis (OA) adopt an abnormal gait pattern, and often develop frontal plane laxity at the knee. The purpose of this study was to quantify the extent of frontal plane knee joint laxity in patients with medial knee OA and genu varum and to assess the effect of joint laxity on knee joint kinetics, kinematics and muscle activity during gait.

DESIGN

Twelve subjects with genu varum and medial compartment knee osteoarthritis (OA group) and 12 age-matched uninjured subjects underwent stress radiography to determine the presence and magnitude of frontal plane laxity. All subjects also went through gait analysis with surface electromyography of the medial and lateral quadriceps, hamstrings, and gastrocnemius to calculate knee joint kinematics and kinetics and co-contraction levels during gait.

RESULTS

The OA group showed significantly greater knee instability (P = 0.002), medial joint laxity (P = 0.001), greater medial quadriceps-medial gastrocnemius (VMMG) co-contraction (P = 0.043), and greater knee adduction moments (P = 0.019) than the control group. Medial joint laxity contributed significantly to the variance in both VMMG and the knee adduction moment during early stance.

CONCLUSION

The presence of medial laxity in patients with knee OA is likely contributing to the altered gait patterns observed in those with medial knee OA. Greater medial co-contraction and knee adduction moments bodes poorly for the long-term integrity of the articular cartilage, suggesting that medial joint laxity should be a focus of interventions aimed at slowing the progression of disease in individuals with medial compartment knee OA.

Les grilles d'évaluations dans la ligamentoplastie du LCA

INTRODUCTION

Recently, results of surgery for anterior cruciate ligament (ACL) have been systematically assessed. Several scales have been developed, but for most rigorous validation is lacking.

METHODOLOGY

We reviewed reports of published scales for ACL surgery and compared their psychometric properties. We searched the MedLine and Cochrane databases with the key words anterior cruciate ligament, surgery, and rating score. A scale was reviewed if its reliability, validity, and responsiveness were reported at least once.

RESULTS

We reviewed four scales (Lysholm and Tegner, Cincinnati, IKDC, and Koos). Test-retest reliability was good, except for the IKDC. For all scales, construct validity could not been ascertained. Responsiveness was acceptable and of the same magnitude for the Lysholm and Tegner, and Cincinnati scales.

CONCLUSION

None of the scales had sufficient psychometric properties and all seemed too complicated for routine use. Validation of a simple scale is needed. Psychometric properties of the last version of the IKDC (IKDC 2000) and the Cincinnati scales should be studied.

Reliability, validity, and responsiveness of the Lysholm knee scale for various chondral disorders of the knee

BACKGROUND

The Lysholm knee scale is a condition-specific outcome measure that was originally designed to assess ligament injuries of the knee. The purpose of this study was to determine the psychometric properties of the Lysholm knee scale for various chondral disorders of the knee.

METHODS

Test-retest reliability, internal consistency, content validity, criterion validity, construct validity, and responsiveness to change were determined for the Lysholm knee scale within subsets of an overall study population of 1657 patients with chondral disorders of the knee. The study population was a heterogeneous group of patients with various types of traumatic and degenerative chondral lesions, including isolated lesions and those associated with meniscal and ligament injuries.

RESULTS

The overall Lysholm knee scale and six of the eight domains had acceptable test-retest reliability (intraclass correlation coefficient = 0.91) and internal consistency (Cronbach alpha = 0.65). The overall Lysholm knee scale demonstrated acceptable floor (0%) and ceiling (0.7%) effects; however, the floor effects for the domain of squatting and the ceiling effects for the domains of limp, instability, support, and locking were unacceptable (>30%). There was acceptable criterion validity with significant (p < 0.05) correlations between the overall Lysholm knee scale and the physical functioning, role-physical, and bodily pain domains of the Short Form-12 scale; the pain, stiffness, and function domains of the Western Ontario and McMaster Universities Osteoarthritis Index; and the Tegner activity scale. The overall Lysholm knee scale had acceptable construct validity, with all nine hypotheses demonstrating significance (p < 0.05), and it had acceptable responsiveness to change (effect size, 1.16; standardized response mean, 1.10), with large effects (> or = 0.80) for the domains of pain, limping, swelling, and squatting and a small effect (> or = 0.20) for the domain of instability.

CONCLUSIONS

The Lysholm knee scale demonstrated overall acceptable psychometric performance for outcomes assessment of various chondral disorders of the knee, although some domains demonstrated suboptimal performance. Psychometric testing of other condition-specific knee instruments in patients with chondral disorders of the knee would be helpful to allow for comparison of psychometric properties.

Get up and go test in patients with knee osteoarthritis

OBJECTIVE

To determine the reliability, minimum detectable change (MDC), and validity of the Get Up and Go (GUG) test.

DESIGN

Repeated-measures test-retest for reliability. Correlational study for validity.

SETTING

Institutional practice.

PARTICIPANTS

Convenience sample of 130 people, 105 with knee osteoarthritis (OA) (80 women; mean age, 62+/-9 y) and 25 healthy controls (21 women; mean age, 57+/-8 y).

INTERVENTIONS

Not applicable. Main outcome measures Western Ontario and McMaster Universities Osteoarthritis Index, the Activity of Daily Living Scale of the Knee Outcome Survey, and the 8 scales of the Medical Outcomes Study 36-Item Short-Form Health Survey.

RESULTS

Intratester and intertester reliability was.95 (95% confidence interval [CI],.72-.98) and.98 (95% CI,.94-.99), respectively. The MDC, based on measurements by a single tester and between testers, was 1.5 and 1.2 seconds, respectively. Time to perform the GUG test was longer for persons with knee OA than it was for the controls (mean difference, 3.3s; 95% CI, 1.8-4.9). Correlations between the GUG test and measures of physical function did not differ significantly from correlations between the GUG test and measures that do not specifically evaluate physical function.

CONCLUSIONS

The GUG test is reliable and has an MDC that is adequate for clinical use. Validity of the GUG test as a single measure of physical function was not supported. Further research should include testing a battery of performance-based measures of physical function.

Knee rating scales

In the past 2 decades, outcome assessment following knee surgery has focused increasingly on the patient's perspective. While traditional measures of outcome, including physical examination, imaging studies, and measures of knee laxity are complementary, questionnaires have become more important in determining the value of a procedure. Reliability, validity, and responsiveness are all important measurement qualities for health-related quality of life instruments. There are several questionnaires available, both for active patients with disorders of the knee, as well as for older patients with degenerative conditions. Activity level is also an important prognostic variable for patients with disorders of the knee. Clinical researchers should also use a validated activity rating scale to evaluate what patients are doing, in addition to how they are doing.

Quadriceps strength and volitional activation before and after total knee arthroplasty for osteoarthritis

INTRODUCTION

Patients with osteoarthritis (OA) of the knee have quadriceps weakness and arthrogenous muscle inhibition (AMI). While total knee arthroplasty (TKA) reliably reduces pain and improves function in patients with knee OA, quadriceps weakness persists after surgery. The purpose of this investigation was to assess contributions of AMI to quadriceps weakness before and after TKA and to assess the effect of pain on AMI.

METHODS

Twenty-eight patients with unilateral, end-stage, primary knee OA were tested an average of 10 days before and 26 days after TKA. The mean age at time of operation was 63 years (range 49-82 years). Measurements on the involved and uninvolved knees were performed using the burst-superimposition technique, where supramaximal electrical stimulation is superimposed on a voluntary contraction. Knee pain during contraction was measured using a numeric rating scale.

RESULTS

The involved quadriceps were significantly weaker than the uninvolved prior to TKA (p<0.05). Quadriceps strength decreased by 60% (p<0.001) and activation decreased 17% (p<0.001) after TKA. Changes in muscle activation accounted for 65% of the variability in the change in quadriceps strength (r(2)=0.65) (p<0.001). Knee pain during muscle contraction accounted for a small, but significant portion of the change in voluntary activation (r(2)=0.22) (p=0.006).

DISCUSSION

Exercise regimens that emphasize strong muscle contraction and clinical tools that facilitate muscle activation like biofeedback and neuromuscular electrical stimulation may be necessary to reverse the quadriceps activation failure and weakness in the patients with knee OA that worsens after TKA. The failure of current rehabilitation regimens to directly address activation deficits within the first months after surgery may explain the persistent quadriceps weakness in patients after TKA.

A comparison of two time intervals for test-retest reliability of health status instruments

Studies of test-retest reliability for health-related quality of life instruments have used varying intervals between test administrations. There is no evidence available to aid in the selection of the time interval between questionnaire administrations for a study of test-retest reliability for health status instruments. We compared the test-retest reliability at 2 days and 2 weeks for four knee-rating scales and the eight domains of the SF-36. Seventy patients with disorders of the knee who were in a stable state were randomly allocated to repeat the questionnaires at either 2 days or 2 weeks. There were no statistically significant differences in the test-retest reliability (intraclass correlation coefficient and limits of agreement statistics) for the two time intervals.

Evaluation of the validity of the AOFAS Clinical Rating Systems by correlation to the SF-36

This study evaluates the validity of the AOFAS Clinical Rating Systems by examining their level of correlation to the Medical Outcomes Study Short Form-36 (SF-36) in patients with foot and ankle complaints. The SF-36 is an extensively validated outcomes tool that has been used as a benchmark in examining the validity of outcomes instruments designed for the upper extremity, knee, shoulder, and general orthopaedic conditions. The study sample was 91 patients seen at the foot and ankle clinic of a university-based orthopaedic practice. Patients were administered both the AOFAS Clinical Rating Systems and SF-36 instruments. Pearson correlation coefficients of the AOFAS scores to the SF-36 sub-scales ranged from 0.02 to 0.36 in the overall study population. Correlation was higher for the sub-set of patients with ankle-hindfoot disorders (0.11 to 0.53) than patients with forefoot disorders (-0.05 to 0.25). The low levels of correlation seen in this study suggest poor construct validity of the AOFAS Clinical Rating Systems.

Systematic review of the quality of randomized controlled trials for patellofemoral pain syndrome

STUDY DESIGN

Systematic review of the literature.

OBJECTIVES

To develop a grading scale to judge the quality of randomized clinical trials (RCTs) and conduct a systematic review of the published RCTs that assess nonoperative treatments for patellofemoral pain syndrome (PFPS).

BACKGROUND

Systematic reviews of the quality and usefulness of clinical trials allow for efficient synthesis and dissemination of the literature, which should facilitate clinicians' efforts to incorporate principles of evidence-based practice in the clinical decision-making process.

METHODS AND MEASURES

Using a scale based on criteria in the Cochrane Collaboration Handbook, we sought to critically appraise the methodology used in RCTs related to the nonoperative management of PFPS, synthesize and interpret our results, and report our findings in a user-friendly fashion. A scale to assess the methodological quality of trials was designed and pilot tested for its content and reliability. Published RCTs identified during a literature search were then selected and rated by 6 raters. We used predefined cutoff scores to identify specific weaknesses in the clinical research process that need to be improved in future clinical trials.

RESULTS

The quality scale we developed was demonstrated to be sufficiently reliable to warrant interpretation of the reviewers' findings. The percentage of trials that met a minimum level of quality for each specific criterion ranged from a low of 25% for the adequacy of the description of the randomization procedure to a high of 95% for the description and standardization of the intervention.

CONCLUSIONS

Based on the results of trials exhibiting a sufficient level of quality, treatments that were effective in decreasing pain and improving function in patients with PFPS were acupuncture, quadriceps strengthening, the use of a resistive brace, and the combination of exercises with patellar taping and biofeedback. The use of soft foot orthotics in patients with excessive foot pronation appeared useful in decreasing pain. In addition, at a short-term follow-up, patients who received exercise programs were discharged earlier from physical therapy. Unfortunately, most RCTs reviewed contained qualitative flaws that bring the validity of the results into question, thus diminishing the ability to generalize the results to clinical practice. These flaws were primarily in the areas of randomization procedures, duration of follow-up, control of cointerventions, assurance of blinding, accountability and proper analysis of dropouts, number of subjects, and the relevance of outcomes. Also, given the limited number of high-quality clinical trials, recommendations about supporting or refuting specific treatment approaches may be premature and can only be made with caution.

Evaluation of the construct validity of the DASH questionnaire by correlation to the SF-36

The construct validity of the Disabilities of the Arm, Shoulder, and Hand (DASH) questionnaire was evaluated by examining its correlation to the Medical Outcomes Study Short Form-36 (SF-36). The study sample was 90 patients seen at the upper-extremity clinic of a university-based orthopedic practice. Patients were asked to complete a packet that included the DASH and SF-36 questionnaires. Pearson correlation coefficients of the DASH questionnaire to the SF-36 subscales ranged from -0.36 to -0.62. The DASH questionnaire had fewer ceiling and floor scores than most of the SF-36 subscales. These results support the DASH questionnaire as a valid measure of health status useful in patients with a wide variety of upper-extremity complaints.