William I. Sterett

Gender differences in lower extremity kinematics, kinetics and energy absorption during landing

OBJECTIVE To determine whether gender differences exist in lower extremity joint motions and energy absorption landing strategies between age and skill matched recreational athletes. DESIGN Mixed factor, repeated measures design. BACKGROUND Compared to males, females execute high demand activities in a more erect posture potentially predisposing the anterior cruciate ligament to greater loads and injury. The preferred energy absorption strategy may provide insight for this performance difference. METHODS Inverse dynamic solutions estimated lower extremity joint kinematics, kinetics and energetic profiles for twelve males and nine females performing a 60 cm drop landing. RESULTS Females demonstrated a more erect landing posture and utilized greater hip and ankle joint range of motions and maximum joint angular velocities compared to males. Females also exhibited greater energy absorption and peak powers from the knee extensors and ankle plantar-flexors compared to the males. Examinations of the energy absorption contributions revealed that the knee was the primary shock absorber for both genders, whereas the ankle plantar-flexors muscles was the second largest contributor to energy absorption for the females and the hip extensors muscles for the males. CONCLUSIONS Females may choose to land in a more erect posture to maximize the energy absorption from the joints most proximal to ground contact. RELEVANCE Females may be at a greater risk to anterior cruciate ligament injury during landing due to their energy absorption strategy.

Relationships Between Objective Assessment of Ligament Stability and Subjective Assessment of Symptoms and Function After Anterior Cruciate Ligament Reconstruction

Background Relationships between objective assessment of ligament stability and subjective assessment of symptoms and function after anterior cruciate ligament reconstruction have not been established. Hypothesis Relationships exist between objective and subjective assessments after anterior cruciate ligament reconstruction. Study Design Case series. Methods Patients (N = 202) undergoing anterior cruciate ligament reconstruction with 2-year minimum follow-up were studied. Objective variables of ligament stability at follow-up included instrumented laxity, Lachman examination, and pivot-shift examination. Subjective variables of symptoms at follow-up included pain, swelling, giving way, locking, crepitus, stiffness, and limping. Subjective function at follow-up included walking, squatting, stair climbing, running, cutting, jumping, twisting, activity limitation, sports level, activities of daily living level, work level, knee function, sports participation, Lysholm score, and satisfaction withoutcome. Results Instrumented knee laxity and Lachman examination had no significant (P> .05) relationships with any subjective variables of symptoms and function. Pivot-shift examination had significant associations with satisfaction (P= .03), partial giving way (P= .01), full giving way (P= .01), difficulty cutting (P= .01), difficulty twisting (P= .01), activity limitation (P= .01), overall knee function (P= .03), sports participation (P= .02), and Lysholm score (P= .01). Conclusions The pivot-shift examination may be a better measure of “functional instability” than instrumented knee laxity or Lachman examination after anterior cruciate ligament reconstruction.

Determinants of Patient Satisfaction with Outcome After Anterior Cruciate Ligament Reconstruction

Background: The purpose of this study was to identify the determinants of patient satisfaction with the outcome after reconstruction of the anterior cruciate ligament.Methods: A cohort of 201 patients undergoing primary reconstruction of the anterior cruciate ligament was studied prospectively. All patients were followed for a minimum of two years (mean, 35.9 months). The dependent variable was patient satisfaction with the outcome, graded ordinally on a scale of 1 to 10. Nonparametric univariate analysis and multivariable modeling were performed to identify determinants of satisfaction.Results: The demographic variables were not found to have a significant association (p > 0.05) with patient satisfaction. The variables at surgery demonstrated a significant association (p < 0.05) with patient satisfaction only with respect to the status of the lateral meniscus, the presence of osteophytes, and concurrent plica excision. The objective variables at follow-up revealed that patients were significantly less satisfied (p < 0.05) if they had a flexion contracture, increased laxity of the involved leg on the manual maximum test as measured on a KT-1000 device, an abnormal result on the pivot-shift examination, effusion, or tenderness at the medial joint line or patella. With regard to the subjective symptoms at follow-up, patients were found to be significantly (p < 0.05) less satisfied with the outcome if they had symptoms of pain, swelling, partial giving-way, full giving-way, locking, noise, stiffness, or a limp. Analysis of the subjective function at follow-up demonstrated that patients were significantly less satisfied (p < 0.05) with the outcome if they had a lower level of activity, sports activity, strenuous work, activities of daily living, overall knee function, sports participation, or symptom-free activity; if they were unemployed; or if they had difficulty with walking, squatting, ascending or descending stairs, running, jumping, cutting, or twisting. Patient satisfaction was significantly associated (p < 0.05) with the Lysholm knee score, overall International Knee Documentation Committee (IKDC) knee score, IKDC subjective subscore, IKDC symptoms subscore, and IKDC range-of-motion subscore. The seven independent multivariate determinants (adjusted R 2 = 0.83, p < 0.001) of patient satisfaction included the Lysholm score, overall subjective knee function, IKDC range-of-motion subscale, patellar tenderness, full giving-way, flexion contracture, and swelling.Conclusions: Univariate and multivariate determinants of patient satisfaction with the outcome after reconstruction of the anterior cruciate ligament were established. Although some specific surgical and objective variables were important, subjective variables of symptoms and function had the most robust associations with patient satisfaction. In assessing the outcome of reconstruction from the perspective of patient satisfaction with the outcome, we should emphasize patient-derived subjective assessment of symptoms and function, particularly those involving issues of stiffness, giving-way, swelling, and patellofemoral symptoms.

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.

Chondral Resurfacing and High Tibial Osteotomy in the Varus Knee

Background Treatment of patients with degenerative knees and varus malalignment presents a difficult clinical problem. Hypothesis Combining a medial opening wedge high tibial osteotomy with the microfracture chondral resurfacing procedure is a viable treatment option. Study Design Retrospective review of prospectively collected data. Methods A group of 38 consecutive patients (mean age, 51.3 years; range, 34 to 72 years; 29 men and 10 women) with varus malalignment and chondral lesions who were treated with chondral resurfacing (an abrasion and microfracture technique) combined with a medial opening wedge high tibial osteotomy. All patients had >5° of varus malalignment. Patients were evaluated preoperatively with the Lysholm and Western Ontario & McMasters Universities Osteoarthritis Index scoring systems and at a minimum of 2 years follow-up. Results Thirty-three of 38 patients (87%) were available for 2-year follow-up (average, 45 months; range, 24 to 80 months). Lysholm scores improved from a preoperative score of 43.5 to 78.0 at follow-up; Western Ontario & McMasters Universities Osteoarthritis Index scores improved from 45.8 to 16.2. The average Tegner score was 5.0. Conclusions Combining a medial opening wedge high tibial osteotomy with the microfracture chondral resurfacing procedure in the varus knee is an effective method of decreasing pain and increasing function at a minimum of 2 years follow-up.

Internal and External Tibial Rotation Strength After Anterior Cruciate Ligament Reconstruction Using Ipsilateral Semitendinosus and Gracilis Tendon Autografts

The internal and external tibial rotation torques of subjects who had undergone anterior cruciate ligament reconstruction using semitendinosus and gracilis tendon grafts were measured to determine whether harvest of the tendons results in weakness of tibial internal and external rotation. Cybex NORM dynamometer examinations were performed to measure internal and external tibial torque at angular velocities of 60, 120, and 180 deg/sec in 23 subjects. The sex-specific average torque data of the reconstructed limbs were compared with those of the contralateral limbs. Relative internal and external torque scores were calculated for each subject by subtracting the peak torque of the reconstructed knee from that of the contralateral knee. These relative scores were averaged and compared with the null hypothesis that each score should be statistically similar to zero. Subjects were evaluated at an average of 51 40 months postoperatively. The mean relative internal torque scores of the reconstructed limbs showed a statistically significant decrease from those of the contralateral limbs at all angular velocities. The mean relative external torque scores of the reconstructed limbs were statistically similar to those of the contralateral limbs at all angular velocities. Subjects who had undergone ligament reconstruction using semitendinosus and gracilis tendons demonstrated internal tibial rotation weakness in their reconstructed knees compared with their contralateral knees at all angular velocities tested. These results suggest that semitendinosus and gracilis tendon harvest causes weakness of internal tibial rotation.

Chondral Resurfacing and High Tibial Osteotomy in the Varus Knee Survivorship Analysis

Background: Active patients with arthritic malalignment of the knee are difficult to manage. Arthroplasty, unicompartmental or total knee replacement, may not be appropriate in patients who desire to remain highly active. High tibial osteotomy has been recommended for the treatment of varus osteoarthritis to decrease pressure on the damaged medial compartment. Purpose: To determine the length of time patients with varus gonarthrosis can avoid knee arthroplasty with chondral resurfacing (microfracture) and medial opening wedge high tibial osteotomy (HTO). Study Design: Case series; Level of evidence, 4. Methods: From 1995 to 2001, the senior authors performed a medial opening wedge HTO/microfracture in 106 knees (mean age, 52 years; range, 30-71 years). Survivorship was defined as not requiring knee arthroplasty after microfracture and HTO. Results: At 5 years, survivorship was 97%. At 7 years, survivorship was 91%. Twelve patients proceeded to arthroplasty at a mean of 81 months (range, 19-116 months). Follow-up was obtained for 90% of patients. At most recent follow-up, the mean Lysholm score was 71 (range, 5-100). At 3 years, the mean Lysholm score was 73, Tegner score was 2.8, and patient satisfaction was 7.9. At 5 years, the mean Lysholm score was 73, Tegner score was 3.8, and patient satisfaction was 7.5. At 9 years, the mean Lysholm score was 67, Tegner score was 3.1, and patient satisfaction was 7.5. Patients with medial meniscus injury at surgery were 9.2 times more likely to undergo arthroplasty than patients without (95% confidence interval [CI], 1.4-13.5; P = .015). Conclusion: With 91% survivorship at 7 years, microfracture/HTO seems to contribute to a delay of knee replacement in active patients with varus gonarthrosis. Patients who proceeded to knee arthroplasty after combined HTO/microfracture had a mean delay of 81.3 months.

Effect of Functional Bracing on Knee Injury in Skiers With Anterior Cruciate Ligament Reconstruction A Prospective Cohort Study

Background The role of knee bracing in anterior cruciate ligament reconstructions is controversial. Hypothesis Functional bracing will have an effect on subsequent knee injury in skiers with anterior cruciate ligament reconstruction. Study Design Cohort study; Level of evidence, 3. Methods From 1991 to 1997, 11606 skiers at a major destination ski resort underwent preseason knee screening. The anterior cruciate ligamentreconstructed group consisted of 820 skiers who had had an anterior cruciate ligament reconstruction 2 years or more earlier. Of these, 257 skiers selected the use of functional knee brace during skiing. The dependent variable was subsequent knee injury, identified via workers compensation records. Covariates included age, gender, ski occupation, Lachman grade, pivot-shift grade, KT-1000 arthrometer manual maximum displacement, and use of a functional brace. Univariate and multivariate risk factors for subsequent knee injury were determined. Results In this study, 257 skier-employees with anterior cruciate ligament reconstruction wore braces and 563 skier-employees with anterior cruciate ligament reconstruction did not. Braced skiers had significantly higher preseason rates of grade II or higher Lachman and pivot-shift tests (braced, 29% and 22%, respectively; nonbraced, 11% and 10%, respectively;P >. 05). Sixty-one subsequent knee injuries were identified, 51 (8.9 injuries/100 knees/ski season) in the nonbraced group and 10 (4.0 injuries/100 knees/ski season) in the braced group (P=. 009). Nonbraced skiers were 2.74 times more likely to suffer subsequent injury than were braced skiers (odds ratio, 2.74 [confidence interval, 1.2-4.9]). Logistic regression modeling identified nonbracing as a significant independent multivariate risk factor for subsequent knee injury in the high-demand skiers with anterior cruciate ligament reconstruction. Conclusion Because of the increased risk of subsequent knee injury in nonbraced skiers, the authors recommend functional bracing for skiers with anterior cruciate ligament reconstruction. Whether the protective effect of functional bracing can be extrapolated to other high-demand patients is yet to be determined.

Comparative injury rates of uninjured, anterior cruciate ligament-deficient, and reconstructed knees in a skiing population

To evaluate the risks of skiing after anterior cruciate ligament injury with or without reconstruction, we performed a 3-year study of 5646 skiers employed by a large ski resort. All skiers underwent knee ligament examinations before entering the study. The participants were divided into three groups based on whether they had never had an anterior cruciate ligament injury (N 4748), were unilaterally deficient of the ligament (N 138), or had undergone a unilateral reconstruction of the ligament at least 1 year before (N 274). The rates of knee injuries requiring evaluation by a physician or time off work were calculated. The results of the reconstructed knees were further evaluated to determine whether ligament repair with semitendinosus/gracilis or patellar tendon autograft had a higher injury rate. Compared with knees with intact anterior cruciate ligaments, ligament-deficient knees had a 6.2-times higher rate of injuries, and knees in which the ligament had been reconstructed had a 3.1-times higher rate. The differences between each of the three groups were significant. Injuries to ligament-intact knees were less severe, with 13% requiring surgery, while 39% of the injuries in the ligament-deficient and 41% of the injuries in the reconstructed-ligament knees required surgery. The rates of injury for the graft types were not significantly different, but skiers with a semitendinosus/gracilis tendon autograft were significantly more likely to rupture their graft than skiers with a patellar tendon autograft.

The surgical treatment of knee injuries in skiers

Although the overall skin injury incidence continues to decline, knee injuries requiring surgery remain extremely common. Emphasis is placed on the history of the skiers fall in making an accurate diagnosis. This injury pattern is then assessed with the skiers age and activity level in determining the most appropriate surgical procedure. The actual surgical intervention is just a portion of the rehabilitation process in returning a skier back to sport as quickly as possible. The most common injuries requiring surgical intervention include meniscal tears, osteochondral fractures, and ligament tears. Our indications and techniques are described. Early focus on postoperative range of motion is emphasized. Strengthening begins only when full, pain-free range of motion is obtained. Utilizing these principles, our goals have been to complete the rehabilitation process coexistent with healing of the injury.