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Biomedical subjects

J Richard Steadman

Publications and source records attributed to J Richard Steadman.

At least 19 recordsLinked to original sources
PubMed2006

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 ligament-reconstructed 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.

Adolescent↗
PubMed2006

Effects of calcified cartilage on healing of chondral defects treated with microfracture in horses.

BACKGROUND: Microfracture of full-thickness articular defects has been shown to significantly enhance the amount of repair tissue. However, there is a suggestion that leaving calcified cartilage inhibits this repair response. HYPOTHESIS: Removal of the calcified cartilage with retention of subchondral bone enhances the amount of attachment of the repair tissue compared with retention of the calcified cartilage layer. STUDY DESIGN: Controlled laboratory study. METHODS: There were 1-cm(2) articular cartilage defects made in 12 skeletally mature horses on the axial weightbearing portion of both medial femoral condyles. Using a custom measuring device and direct arthroscopic observation of the subchondral bone beneath the calcified cartilage layer, the authors removed the calcified cartilage from 1 defect of each horse. The repair was assessed with arthroscopy, clinical examination, radiographic and magnetic resonance imaging examinations, biopsy at 4 months, gross and histopathologic examinations at 12 months, as well as mRNA and immunohistochemical evaluations. RESULTS: Removal of calcified cartilage with retention of the subchondral bone plate increased the overall repair tissue as assessed by arthroscopic (4 months) and gross evaluation (12 months). An increase in the level of the subchondral bone was also observed with removal of the calcified cartilage layer. The clinical pain, radiographic examinations, magnetic resonance imaging evaluations, histologic character, matrix proteins, or mRNA expression do not appear to differ based on level of defect debridement. CLINICAL RELEVANCE: Removal of the calcified cartilage layer appears to provide optimal amount and attachment of repair tissue. Therefore, close arthroscopic visualization is recommended for debridement of clinical lesions to ensure removal of the calcified cartilage layer.

Animals↗
PubMed2006

A clinical composite score accurately detects meniscal pathology.

PURPOSE: Five common tests were used to diagnose meniscal tears when used as a composite score. We evaluated how effectively the composite examination, when performed in the presence of an anterior cruciate ligament (ACL) injury or degenerative joint disease (DJD), determined the presence of meniscal tears. METHODS: Data were collected prospectively on all patients at our clinic with a primary knee complaint. Independent variables included the presence or absence of the following: (1) a history of "catching" or "locking" as reported by the patient, (2) pain with forced hyperextension, (3) pain with maximum flexion, (4) pain or an audible click with McMurray's maneuver, and (5) joint line tenderness to palpation. Comprehensive patient demographic data were collected including ligamentous examinations and other intra-articular pathologies found at arthroscopy. Composite examination findings were correlated with the presence or absence of meniscal pathology. RESULTS: We evaluated 635 knees in 576 patients for historical and physical findings. Of the knees, 209 underwent arthroscopic surgery and 426 did not. Chi(2) Analysis showed a significant relation between the number of positive diagnostic tests and the presence of meniscal tears (P = .001). Five positive findings on composite examination yielded a positive predictive value of 92.3%. Positive predictive values remained greater than 75% with composite scores of at least 3 in the absence of ACL and DJD pathologies. The presence of an ACL injury decreased the positive predictive value of 5 composite findings to 67%, whereas the presence of DJD increased predictability to 100%. CONCLUSIONS: When all 5 symptoms and signs were positive, there was a 92.3% positive predictive value of finding a meniscal tear. Although positive predictive values decreased with a concomitant ACL injury and increased with DJD, there was a higher rate of false-positive findings (ACL) and false-negative findings (DJD). LEVEL OF EVIDENCE: Level II, development of diagnostic criteria with consecutive patients and gold standard.

Adolescent↗
PubMed2006

Microfracture of the hip in athletes.

Most studies addressing treatment of chondral injuries have involved the knee. Various techniques have been used in the knee. Microfracture has shown excellent results in the knee. Chondral injuries of the hip are common in athletes with labral tears and femoroacetabular impingement. The microfracture technique is now being used in the hip joint. Indications include full-thickness cartilage loss or unstable flap on a weight-bearing surface. An important contraindication is the patients unwillingness to follow the postoperative protocol and rehabilitation plan. The microfracture technique in the hip is similar to that in the knee. Postoperatively, patients use a continuous passive motion and are flat foot (20 lbs.) weightbearing for 8 weeks. Early results following microfracture in the hip have been encouraging.

Acetabulum↗
PubMed2006

A minimally invasive technique ("healing response") to treat proximal ACL injuries in skeletally immature athletes.

This study documents outcomes of athletically active, skeletally immature patients with proximal anterior cruciate ligament (ACL) tears treated with a non-reconstructive technique to promote healing ("healing response"). Between 1992 and 1998, 13 skeletally immature athletes with proximal ACL tears underwent a healing response procedure. Patients with previous ACL injury, other concurrent ligament pathology, and/or complete mid-substance ACL tears were excluded. Average preoperative KT-1000 arthrometer manual maximum difference for all patients was 5 mm (range: 3-10 mm). Preoperatively, all patients had a 1+ or 2+ pivot shift, and all patients reported knee function as abnormal or severely abnormal. Patients were followed prospectively with clinical examinations, KT-1000 testing, and subjective questionnaires. Three (23%) patients had a re-injury 30 to 55 months after the healing response and underwent subsequent ACL reconstruction. Subjective follow-up on the remaining 10 patients at an average of 69 months (range: 26-113 months) postoperatively indicated no patients experienced pain or giving way, and all considered their knee function normal. Average Lysholm score was 96, Tegner score was 8.5 (range: 7-10), and patient satisfaction at follow-up was 9.9 (1=very dissatisfied and 10=very satisfied). Clinical examination at least one year postoperatively was performed on 7 of 10 patients at 35 months (range: 12-63 months). Five patients had a negative pivot shift and 2 had a 1+ pivot shift. KT-1000 measurements improved to 2 mm (range: 0-3 mm). In the athletically active, skeletally immature patient, the healing response procedure can restore stability and knee function, with proper patient selection. In this study group, patients were very satisfied with the procedure and returned to a high level of sports and activities.

Activities of Daily Living↗
PubMed2006

Healing of a surgically created partial detachment of the posterior cruciate ligament using marrow stimulation: an experimental study in dogs.

The inability of intra-articular (cruciate) ligaments to generate a substantive reparative response may preclude the primary surgical repair of such lesions. A marrow stimulation technique that provides access to a fibrin scaffold, cytokines, and mesenchymal stem cells has been shown to be successful in generating a repair response in articular cartilage. We hypothesized that a similar approach may be effective in initiating and supporting a healing response in cruciate ligament injuries. The ability to treat cruciate ligament injuries by primary repair may have significant advantages over the more extensive reconstructive procedures currently advocated. Bilateral subtotal (75% of width) lacerations were made in the proximal aspect of the posterior cruciate ligament (PCL) in 10 adult mongrel dogs. A marrow stimulation technique in which small holes were made through the femoral origin of the PCL into the marrow cavity immediately adjacent to the lesion was performed in one limb. The contralateral limb served as the non-stimulated control. Twelve weeks after surgery the extent of healing and the histological character of the repair tissue in both groups were compared. Marrow stimulation resulted in a statistically significant (P<.05) improvement in the healing of subtotal lacerations made in the PCL. The marrow-stimulated repair tissue was more cellular and had a more organized extracellular matrix than the repair tissue in the non-stimulated group. Our hypothesis was confirmed. Marrow stimulation can induce a "healing response" in intra-articular (cruciate) ligaments. This technique may have clinical applications in primary surgical repair of these structures.

Animals↗
PubMed2006

Reliability, validity, and responsiveness of the Lysholm knee score and Tegner activity scale for patients with meniscal injury of the knee.

BACKGROUND: A torn meniscus is one of the most common indications for knee surgery. The purpose of this study was to determine the psychometric properties of the Lysholm knee score and the Tegner activity scale when used for patients with a meniscal injury of the knee. METHODS: Test-retest reliability, content validity, criterion validity, construct validity, and responsiveness to change were determined for the Lysholm score and the Tegner activity scale. Test-retest reliability was measured in a group of 122 patients at least two years after they had undergone surgery for a meniscal lesion. This group completed a follow-up form and then completed it again within four weeks. The other tests were performed in a group of 191 patients who had only a meniscal lesion at the time of the surgery and a group of 477 patients who had a meniscal lesion and other intra-articular lesions. RESULTS: The overall Lysholm score showed acceptable test-retest reliability, floor and ceiling effects, criterion validity, construct validity, and responsiveness to change. There were unacceptable ceiling effects (>30%) for the Lysholm domains of limp, instability, support, and locking. The Tegner activity scale showed acceptable test-retest reliability, floor and ceiling effects, criterion validity, construct validity, and responsiveness to change. CONCLUSIONS: Overall, the Lysholm knee score and the Tegner activity scale demonstrated acceptable psychometric performances as outcome measures for patients with a meniscal injury of the knee. Some domains of the Lysholm score showed suboptimal performance, and the Tegner scale had only a moderate effect size. Psychometric testing of other condition-specific knee instruments for patients with a meniscal lesion of the knee would be helpful to allow comparison of the properties of the various knee instruments.

Humans↗
PubMed2005

Tissue-engineered collagen meniscus implants: 5- to 6-year feasibility study results.

PURPOSE: In this feasibility study, a 5- to 6-year clinical follow-up evaluation was conducted on 8 patients who had undergone reconstruction of 1 injured medial meniscus with a tissue-engineered collagen meniscus implant. The hypothesis was that these patients would show significant clinical improvement over their preoperative status and would have maintained their status determined at the 2-year follow-up evaluation. TYPE OF STUDY: Prospective longitudinal feasibility study follow-up evaluation. METHODS: Eight patients underwent arthroscopic placement of a collagen meniscus implant by a single surgeon to reconstruct and restore the irreparably damaged medial meniscus of 1 knee. All patients returned for clinical, radiographic, magnetic resonance imaging, and arthroscopic examinations an average of 5.8 years (range, 5.5-6.3 y) after collagen meniscus implant placement. RESULTS: Lysholm scores improved significantly (P = .045) from 75 preoperatively to 88 at most recent follow-up evaluation. Average Tegner activity scores improved significantly (P = .001) from 3 to 6. Patient self-assessment improved significantly (P = .046) from 2.4 to 1.9 (1 = normal, 4 = severely abnormal). Pain scores improved from 23 to 11 (0 = no pain, 100 = worst pain). Imaging studies confirmed that the chondral surfaces of the medial compartment had not degenerated further since the placement of the implant 5.8 years earlier. Relook arthroscopy with direct measurement of the newly generated tissue revealed 69% defect filling. Histologic assessment of tissue biopsy specimens from 3 patients showed the presence of fibrocartilage with a uniform extracellular matrix. CONCLUSIONS: The meniscus-like tissue that developed after collagen meniscus implant placement has maintained its structure and functioned without negative effects for more than 5 years. The hypothesis was affirmed that these patients were improved significantly compared with their preoperative status and unchanged compared with 2-year evaluations. LEVEL OF EVIDENCE: Level IV.

Adult↗
PubMed2005

Second-look arthroscopic observations after radiofrequency treatment of partial thickness articular cartilage defects in human knees: report of four cases.

Partial thickness articular cartilage defects in the knee are commonly encountered clinical problems. Recently, use of radiofrequency-based devices for performing arthroscopic chondroplasty has gained popularity. However, published experimental studies using different methods for evaluating the histologic effects of radiofrequency-chondroplasty on surrounding cartilage offer contradictory results. To date, few clinical findings after radiofrequency-based chondroplasty have been reported. We present four patients where follow-up arthroscopy documented partial thickness articular defects treated previously with radiofrequency-based chondroplasty to be completely filled with stable repair tissue. No attempt was made to stimulate cartilage regeneration (ie, abrasion or microfracture) in any of these cases.

Adult↗
PubMed2004

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 degrees 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.

Adult↗
PubMed2004

Gait retraining after anterior cruciate ligament reconstruction.

OBJECTIVES: To examine the effects of 2 gait retraining protocols on the gait patterns of patients with bone-patellar tendon-bone anterior cruciate ligament (ACL) reconstruction. DESIGN: Randomized control, repeated-measures design. SETTING: Private orthopedic center and research facility. PARTICIPANTS: Sixteen patients with bone-patellar tendon-bone ACL reconstruction, randomly subdivided into 2 groups (group 1, n=8; group 2, n=8), and a healthy control group of 8 subjects. INTERVENTION: The 16 subjects with ACL reconstruction were randomly assigned to 2 different gait retraining protocols over a 6-week training interval: (1). a protocol using a predicted stride frequency calculated from the resonant frequency of a force-driven harmonic oscillator (FDHO) model or (2). a protocol using the preferred stride frequency (PSF). MAIN OUTCOME MEASURES: Gait analyses examining the lower-extremity kinematic, kinetic, and energetic gait patterns of each group. RESULTS: Gait retraining with the FDHO model showed improvements in lower-extremity positions, hip and knee extensor angular impulse, and work parameters. Gait retraining with the PSF demonstrated no statistical improvements. The FDHO training protocol facilitated a greater midstance knee range of motion (ROM) and greater rates of improvement for midstance ROM, hip extensor angular impulse, and concentric hip extensor work. CONCLUSIONS: Gait retraining with the resonant frequency of an FDHO model facilitated a greater recovery of gait function compared with training with the PSF.

Adult↗
PubMed2004

Patient satisfaction and outcome after microfracture of the degenerative knee.

Satisfaction and functional outcome was measured in 81 patients who were treated arthroscopically with microfracture for isolated degenerative lesions of the knee. Average patient age was 49 years (range: 40-70 years) and average degenerative lesion measured 229.5 mm2 (range: 25-2000 mm2). Patients were evaluated at average 2.6-year follow-up (range: 2-5 years). All subjective parameters measured (pain, swelling, limping, walking, stairs, sport level, and activities of daily living) demonstrated significant improvement over preoperative status (P<.003). Lysholm score improved from 53.8 to 83.1 (P<.001), and mean Tegner Activity Scale score improved from 2.9 to 4.5 (P<.05). No significant association was noted between Lysholm improvement and gender or age. Significant improvement in mean Lysholm score was noted for lesions in all three knee compartments. Thirteen patients required repeat arthroscopy within 5 years of initial microfracture for lysis of adhesions. Five patients required revision microfracture to a previously treated lesion or total knee arthroplasty at an average of 23 months (range: 5-36 months) from the initial microfracture. Microfracture is an efficacious surgical option for the treatment of degenerative chondral lesions of the knee. The modest rate of failure and need for arthroscopic lysis of adhesions reflects the challenge of joint-sparing arthroscopic surgery in the degenerative knee.

Arthroscopy↗
PubMed2004

Early ACL reconstruction in combined ACL-MCL injuries.

This study reports 18 patients with 19 combined ligament injuries with complete anterior cruciate ligament (ACL) tear and a minimum grade II medial collateral ligament (MCL) tear who underwent early reconstruction of the ACL and nonoperative treatment of the MCL. Inclusion criteria included ACL reconstruction performed within 3 weeks of initial injury, no history of antecedent injury to the ipsilateral knee, and 2-year follow-up data. Associated injuries were noted in 11 patients including 6 isolated lateral meniscal tears, 1 isolated medial meniscal tear, 5 combined meniscal tears, 1 chondral injury, and 1 patellar fracture. Subjective minimum 2-year follow-up yielded a mean Lysholm score of 94.5 and a mean Tegner activity score of 8.4. Serial clinical examinations demonstrated good functional outcomes, range of motion, and strength. No patient experienced ACL graft failure or valgus instability or required subsequent surgery for chondral or meniscal damage. One patient required a second surgery for arthrofibrosis. Clinical and functional outcomes in this study were good with low motion complication rates. Based on our data, early surgical reconstruction of the ACL and nonoperative treatment of the MCL in combined injuries is acceptable and results in excellent clinical and functional outcomes.

Adolescent↗
PubMed2004

Comparison of tibial rotation strength in patients' status after anterior cruciate ligament reconstruction with hamstring versus patellar tendon autografts.

OBJECTIVE: To determine if there are tibial rotational strength deficits in individuals treated with a semitendinosus/gracilis or bone-patella tendon-bone (BTB) autografts for ACL reconstruction. DESIGN: Retrospective. SETTING: Clinical practice and nonprofit research site. PATIENTS: 102 subjects--34 treated with BTB autograft, 34 treated with a hamstring autograft, and 34 matched controls--were evaluated at an average of 53.1 +/- 36.0 months postoperatively. MAIN OUTCOME MEASUREMENTS: Isokinetic examination at 60, 120, and 180 degrees/s to assess internal (IT) and external tibial (ET) rotation peak torque of the operated knee and contralateral knee. Internal and external tibial rotation peak torque values were evaluated for differences between gender and surgery type (2 x 3 ANOVA). RESULTS: Contrasts of IT torque across groups revealed that surgery type exhibited a significant main effect (P < 0.0001), but gender did not (P = 0.07), and there was no interaction of surgery and gender (P = 0.64). The hamstring group was weaker in IT rotation compared with the BTB and control groups (P < 0.05). No difference was noted in IT rotation torque between BTB and control groups at all test velocities. Contrasts of ET rotation torque across groups revealed that surgery type exhibited a significant main effect (P < 0.0001), but gender did not (P = 0.48). There was no interaction of surgery and gender (P = 0.98). The BTB group was significantly weaker compared with the hamstring group (P < 0.001) and the control group (P < 0.001) in ET at all test velocities. CONCLUSIONS: Residual strength deficits in IT and ET rotation following hamstring graft and BTB graft ACL reconstruction are apparent.

Analysis of Variance↗
PubMed2004

Mechanisms of compensating for anterior cruciate ligament deficiency during gait.

INTRODUCTION: The quadriceps avoidance gait pattern may not be as common in ACL deficient (ACLd) gait as previously described. PURPOSE: The purpose of this study was to investigate the existence of the quadriceps avoidance pattern in ACL deficient patients and to further identify gait compensations that may exist in this subject pool. METHODS: In the present study, hip, knee, and ankle gait kinematics, and kinetics and thigh EMG profiles were recorded and compared for 16 ACLd and 8 control subjects. RESULTS: The quadriceps avoidance gait pattern was not observed for any of the subjects. Hip, knee, and ankle kinematics and kinetics were not different between groups. However, nine ACLd subjects (group A) demonstrated a normal biphasic knee moment pattern, whereas seven (group B) demonstrated an all knee extensor pattern. This indicates different adaptive mechanisms may be present in ACLd gait. Group A exhibited a hip strategy that increased hip extensor output, decreased knee extensor output, and allowed normal knee kinematics. Group B demonstrated a knee strategy that increased the stiffness of the joint and utilized a flexed knee gait. CONCLUSION: The prevalence of multiple adaptive strategies to compensate for ACL deficiency has several important ramifications. First, an ACLd subject pool with mixed compensating strategies may deter the identification of specific coping mechanisms and account for the confounding results in the literature. Second, the importance of the hip extensors should not be overlooked when studying this population.

Adult↗
PubMed2004

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.

Adult↗
PubMed2003

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.

Adult↗