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PubMed1990

Maximal peak torque as a predictor of peak angular impulse and average power of thigh muscles--an isometric and isokinetic study.

The aim of this study was to determine whether isometric and isokinetic peak torque (PT) of hamstring and quadriceps muscles (speed of movement 0 degrees, 60 degrees, and 180 degrees/sec) is a valid predictor of peak angular impulse (PAI) and average power (AP) (180 degrees/sec) in 20 patients after an injury to the lateral collateral ligament (LCL) of the knee. At every test speed the Pearson product moment (r) and the Spearman rank (rs) correlation coefficients between the PT and PAI were highly significant for both muscle groups in the uninjured (r = .71-.96, rs = .76-.96) as well as in the injured (r = .70-.96, rs = .78-.98) knees. The results were the same between the PT and AP (uninjured knee: r = .83-.98, rs = .78-.95; injured knee; r = .64-.97, rs = .74-.96). In both knees and in both muscle groups the correlation coefficients increased towards the highest speed of the isokinetic movement, obviously since the PAI and AP were registered at that speed. In conclusion, concerning LCL insufficient or uninjured knees, the PAI or AP analysis may offer little additional information about thigh muscle function to that attained by more simple measurement, the PT analysis.

Adult↗

PubMed1995

Anthropometric estimation of thigh muscle cross-sectional area.

The purpose of this investigation was to derive and validate circumference and skinfold equations for estimating the anatomical cross-sectional area (CSA) of the quadriceps, hamstrings, and total thigh muscles. Forty-three adult male (mean age +/- SD = 25 +/- 5 yr) volunteers underwent magnetic resonance imaging (MRI) to determine the CSA of the thigh muscles at the midfemur level as well as midthigh circumference and anterior thigh skinfold assessment. Multiple regression analyses were used to derive equations for predicting quadriceps, hamstrings, and total thigh muscle CSA of the dominant limb from the anthropometric dimensions on a random sample of 30 of the subjects. Cross-validation (CV) analyses were performed for each equation on: (a) the nondominant thigh of the derivation group (N = 30); (b) the dominant thigh of the CV group (N = 13); and (c) the nondominant thigh of the CV group (N = 13). The CV total error values for the quadriceps, hamstrings, and total thigh muscle CSA ranged from 5.4 to 14.4, 3.3 to 5.5, and 10.0 to 25.4 cm2, respectively. The anthropometric equations are recommended for one-time estimates of muscle CSA values in healthy, well-nourished young adult males when more sophisticated procedures are not available.

Adult↗

PubMed1990

Nonoperative treatment of acute knee ligament injuries. A review with special reference to indications and methods.

Nonoperative treatment has received little attention in the numerous scientific reports on knee ligament injuries. Great controversy still exists concerning the proper treatment of a knee with a ruptured ligament, especially the anterior cruciate ligament. However, according to the studies of the authors and an extensive review of the literature the indications for conservative management can be established to be all grade I and II sprains (partial tears) of knee ligaments as well as an isolated grade III sprain (complete tear) of the posterior cruciate ligament. In addition, an isolated complete rupture of an anterior cruciate, or medial or lateral collateral ligament may be treated nonoperatively in an older sedentary person. Other injuries obviously call for an operative approach at the acute stage. Nonoperative therapy protocols must be based on the knowledge of the biological phenomenon occurring during connective tissue healing process. In the first phase of ligament healing the injured knee needs 2 to 3 weeks immobilisation for undisturbed fibroblast invasion and proliferation of collagen fibres. This is achieved by immobilising the knee in a rehabilitative knee brace locked in 40 to 45 degrees of flexion. Thereafter, a gradually increasing controlled mobilisation is allowed in the brace to avoid the deleterious effects of immobilisation to cartilage, bone, muscles, tendons and ligaments, and to enhance the orientation of collagen fibres to the stress lines of the healing ligament. After 4 to 8 weeks the goal for rehabilitation is rapid and full recovery to work and sports. A functional knee brace may be used at this phase to give extra protection before final strengthening of the injured ligament. During the mobilisation and muscle training of the therapy protocol various specific techniques can be used for strengthening of the hamstring and quadriceps muscles, including isometric, isotonic, isokinetic and eccentric exercises with or without resistive equipments. In addition, electrical stimulation may help prevent muscle wasting due to immobilisation, and continuous passive motion may be used to correct persistent extension or flexion deficit. Normally, jogging is allowed approximately 3 to 6 months after the injury, and an athlete is generally able to return to full activity and competitive sports after 6 to 12 months. Quite frequently the whole question of successful rehabilitation after a knee ligamentous injury is more motivational rather than methodological and is thus often independent of attending physician's or physiotherapist's skill or will. Therefore, one of the most important things during rehabilitation is to motivate and encourage the patient for longstanding, intensive work.

Biomechanical Phenomena↗

PubMedDate not supplied

Muscle flexibility as a risk factor for developing muscle injuries in male professional soccer players. A prospective study.

BACKGROUND: Muscular tightness is frequently postulated as an intrinsic risk factor for the development of a muscle injury. However, very little prospective data exist to prove this. HYPOTHESIS: Increased muscle tightness identifies a soccer player at risk for a subsequent musculoskeletal lesion. STUDY DESIGN: Prospective cohort study. METHODS: We examined 146 male professional soccer players before the 1999-2000 Belgian soccer competition. None of the players had a history of muscle injury in the lower extremities in the previous 2 years. The flexibility of the hamstring, quadriceps, adductor, and calf muscles of these players was measured goniometrically before the start of the season. All of the examined players were monitored throughout the season to register subsequent injuries. RESULTS: Players with a hamstring (N = 31) or quadriceps (N = 13) muscle injury were found to have significantly lower flexibility in these muscles before their injury compared with the uninjured group. No significant differences in muscle flexibility were found between players who sustained an adductor muscle injury (N = 13) or a calf muscle injury (N = 10) and the uninjured group. CONCLUSIONS: These results indicate that soccer players with an increased tightness of the hamstring or quadriceps muscles have a statistically higher risk for a subsequent musculoskeletal lesion. CLINICAL SIGNIFICANCE: Preseason hamstring and quadriceps muscle flexibility testing can identify male soccer players at risk of developing hamstring and quadriceps muscle injuries.

Athletic Injuries↗

PubMed2005

A novel combination of methods to assess sarcopenia and muscle performance in mice.

A novel combination of assays was developed to assess sarcopenia and muscle performance. Three techniques were tested to assess muscle function both during and upon termination of treatments designed to induce sarcopenia. In unsuspended (US) and hindlimb suspended (HS) mice, a Hindlimb Exertion Force Test (HEFT), cage wheel running, and in vitro muscle electrophysiology were performed. Twelve-week old, mature male C57BL/6J mice were HS (n = 24) for two weeks, or served as US controls (n = 26). Both groups were subjected to a HEFT on day 13; that is, the maximum force exerted against a beam force transducer (2 lb. linear range, Transducer Techniques, Temecula CA) following applied tail shock stimulus (0.15 mA, 300 msec). This test primarily evaluated the hindlimb muscles used for an escape response (i.e., hamstrings, quadriceps and calf muscles). Mice (n = 10-11/group) were given voluntary access to running wheels for 7 days post treatment to evaluate muscle endurance. On day 13, HS mice showed a mean 18.9% (p = 0.002) decrease in the maximum force exerted compared to US mice. After 7 days of wheel running, HS running distance tended to decrease (13.2%, p = 0.084). HS mice ran an average of 2.0 km/day less than US control mice, with similar running patterns: distance declined on day 2 following completion of HS but increased steadily thereafter. With in vitro testing, the maximum soleus tetanus response decreased by 31.8% (p = 0.01) with HS, in agreement with the changes observed by the other assays. These three assays, combined, appear to provide effective and complementary ways to measure muscle performance and functional differences.

Animals↗

PubMed2000

Assessment of neuromuscular response characteristics at the knee following a functional perturbation.

Previous research indicates that both the extent and timing of muscular activation at the knee can be influenced by muscle activity state, joint angle, weight-bearing status and trunk position. However, little research to date has evaluated protective neuromuscular response times and activation patterns to an imposed perturbation with the knee joint in a functional, weight-bearing stance. Hence, we designed a lower extremity perturbation device to produce a sudden, forward and either internal or external rotation moment of the trunk and femur relative to the weight-bearing tibia. Surface electromyography (EMG) recorded long latency reflex times of the medial and lateral quadriceps, hamstring and gastrocnemius muscles in 64 intercollegiate lacrosse and soccer players in response to both internal and external rotation perturbation. We found the gastrocnemius fired significantly faster that the hamstring, which in turn fired significantly faster than the quadriceps. There was also a significant difference in activation times of the medial and lateral hamstring not found for the quadriceps or gastrocnemius muscles. Our findings confirmed that reactive neuromuscular responses following this functional perturbation differ markedly from those previously reported using seated, partial weight-bearing and/or uni-planar models under relaxed conditions.

Adult↗

PubMed2004

Thigh-muscles strength training, dance exercise, dynamometry, and anthropometry in professional ballerinas.

The purpose of the present study was to assess the effects of 12 weeks of quadriceps and hamstring strength training on torque levels after a dance exercise and on selected anthropometric parameters. The sample consisted of 22 (ages, 25 +/- 1.3 years) full-time professional ballerinas who were randomly assigned into experimental (n = 12) and control (n = 10) groups. A dance routine designed to cause fatigue within 5 minutes, isokinetic dynamometry, and anthropometric assessments were conducted before and after strength training in both groups. Before strength training, the dance routine resulted in significant reductions of hamstring (p < 0.001) and quadriceps (p < 0.001) peak torques in both subject groups. However, after strength training, only control subjects demonstrated such torque decrements (p < 0.001) after the dance routine. Furthermore, the experimental group revealed greater knee extension (119 vs. 138 N.m; p < 0.001) and flexion (60 vs. 69 N.m; p < 0.001) torques, smaller sum of skinfolds (33.6 vs. 27.8 mm; p < 0.01), more fat-free mass (37.7 vs. 39.4 kg; p < 0.05), but unchanged body mass (p > 0.05) and thigh circumferences (p > 0.05). A negative relationship (p < 0.001) was found between initial strength levels and improvements measured at the end of the 12-week program. These results suggest that supplementary strength training for hamstring and quadriceps muscles is beneficial to professional ballerinas and their dancing; weaker individuals are more likely to benefit from such regimens than their stronger counterparts, whereas increases in thigh-muscle strength do not alter selected aesthetic components.

Adult↗

PubMed2000

Accuracy of muscle moment arms estimated from MRI-based musculoskeletal models of the lower extremity.

OBJECTIVE: Biomechanical models that compute the lengths and moment arms of soft tissues are broadly applicable to the treatment of movement abnormalities and the planning of orthopaedic surgical procedures. The goals of this study were to: (i) develop methods to construct subject-specific biomechanical models from magnetic resonance (MR) images, (ii) create models of three lower-extremity cadaveric specimens, and (iii) quantify the accuracy of muscle-tendon lengths and moment arms estimated using these models. MATERIALS AND METHODS: Models describing the paths of the medial hamstrings and psoas muscles for a wide range of body positions were developed from MR images in one joint configuration by defining kinematic models of the hip and knee, and by specifying "wrapping surfaces" that simulate interactions between the muscles and underlying structures. Our methods for constructing these models were evaluated by comparing hip and knee flexion moment arms estimated from models of three specimens to the moment arms determined experimentally on the same specimens. Because a muscle's moment arm determines its change in length with joint rotation, these comparisons also tested the accuracy with which the models could estimate muscle-tendon lengths over a range of hip and knee motions. RESULTS: Errors in the moment arms calculated with the models, averaged over functional ranges of hip and knee flexion, were less than 4 mm (within 10% of experimental values). CONCLUSION: The combination of MR imaging and graphics-based musculoskeletal modeling provides an accurate and efficient means of estimating muscle-tendon lengths and moment arms in vivo.

Biomechanical Phenomena↗

PubMed1999

Increasing muscle mass in spinal cord injured persons with a functional electrical stimulation exercise program.

OBJECTIVE: To determine the magnitude of changes in muscle mass and lower extremity body composition that could be induced with a regular regimen of functional electrical stimulation (FES)-induced lower-extremity cycling, as well as the distribution of changes in muscle mass among the thigh muscles in persons with spinal cord injury (SCI). STUDY DESIGN: Thirteen men with neurologically complete motor sensory SCI underwent a 3-phase, FES-induced, ergometry exercise program: phase 1, quadriceps strengthening: phase 2, progressive sequential stimulation to achieve a rhythmic pedaling motion (surface electrodes placed over the quadriceps, hamstrings, and gluteal muscles); phase 3, FES-induced cycling for 30 minutes. Participants moved from one phase to the next when they met the objectives for the current phase. MEASURES: Computed tomography of legs to assess muscle cross-sectional area and proportion of muscle and adipose tissue. Scans were done at baseline (before subjects started the program), at first follow-up, typically after 65.4+/-5.6 (SD) weekly sessions, and at second follow-up, typically after 98.1+/-9.1 sessions. RESULTS: Increases in cross-sectional areas were found in the following muscles: rectus femoris (31%, p<.001). sartorius (22%, p<.025), adductor magnus-hamstrings (26%, p<.001), vastus lateralis (39%, p = .001), vastus medialis-intermedius (31%, p = .025). Cross-sectional area of adductor longus and gracilis muscles did not change. The ratio of muscle to adipose tissue increased significantly in thighs and calves. There was no correlation among the total number of exercise sessions and the magnitude of muscle hypertrophy. CONCLUSIONS: Muscle cross-sectional area and the muscle to adipose tissue ratio of the lower extremities increased during a regular regimen of 2.3 FES-induced lower extremity cycling sessions weekly. The distribution of changes was related to the proximity of muscles to the stimulating electrodes.

Adipose Tissue↗

PubMed1987

Musculoskeletal profile of male collegiate soccer players.

Twenty-five collegiate soccer players were evaluated for lower extremity flexibility and muscle strength at the end of preseason training and before the onset of the collegiate soccer season on two successive seasons. The purpose of the evaluation was to determine whether symmetry was present in their legs and whether deficits in flexibility or strength would affect the susceptibility to hamstring or groin muscle strain injuries. The mean (+/- SE) flexibility of the dominant leg for hip abduction was 41 degrees +/- 1.2 degree; for hip flexion, 76 degrees +/- 1.9 degree; for hip extension, 174 degrees +/- 0.7 degree; and for ankle dorsiflexion, 33 degrees +/- 1.3 degree. The mean (+/- SE) isokinetic torque of the dominant leg (tested at 30 degrees per second) for knee extension was 214 +/- 8 newton meters and for flexion was 128 +/- 4 newton meters, while isometric strength for hip flexion was 315 +/- 8 newtons and for ankle plantar flexion was 1721 +/- 58 newtons. No significant differences were found between the dominant and nondominant legs in flexibility or strength. During this study no hamstring or groin strain injuries occurred. The lack of leg muscle strain injuries appeared to be directly related to the initiation of a controlled warmup and stretching program and underlines the importance of this in injury prevention. Interestingly, more than 50% (13 of 25) of the players were found to have significant deficits in one or more specific muscle groups. Two athletes sustained low back strain injuries and one athlete had a knee sprain injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2005

Morning warming-up exercise--effects on musculoskeletal fitness in construction workers.

The aim of the present study was to evaluate the effects on muscle stretchability, joint flexibility, muscle strength and endurance in construction workers of a 3-month period of a 10-min morning warming-up exercise (MWU), performed at the building site every working day. Thirty construction workers participated in the program. Seventeen construction workers at other building sites served as controls. Muscle stretchability, joint flexibility, muscle strength and endurance were measured before and after the program. Significant increase of thoracic and lower back mobility, increase of hamstring and thigh muscle stretchability were seen in the MWU group. A significant difference in back muscle endurance was found due to decreased endurance in the controls. Muscular strength was not influenced by the MWU. The results indicate that a short dose of morning warming-up exercise could be beneficial for increasing or maintaining joint and muscle flexibility and muscle endurance for workers exposed to manual material handling and strenuous working positions.

Adult↗

PubMed1991

Viral persistence during the developmental phase of Coxsackievirus B1-induced murine polymyositis.

Mice infected with coxsackievirus B1 (CVB1) develop a chronic hindquarter muscle weakness which resembles human polymyositis. In this study, we used in situ hybridization to screen for persistent viral RNA in hamstring and quadriceps muscles from mice that displayed various degrees of clinical weakness. At 28 to 31 days postinfection, when chronic myositis is well developed but infectious virus can no longer be recovered, persistent CVB1 RNA was found in hindquarter skeletal muscle of all 12 infected animals examined. Persistent CVB1 showed a multifocal distribution within muscle and was associated with three different histopathology patterns (HPPs). These three HPPs (HPP-1, HPP-2, and HPP-3) represent potentially different stages in the mechanism of persistence. They are based on the pattern of grains, the location of hybridization signal within the muscle, and the accompanying histopathology. In HPP-1, virus persisted in nonnecrotic muscle fibers and was not directly associated with foci of inflammatory cells. HPP-2 consisted of virus contained within necrotic myocytes that were surrounded by inflammatory cells. HPP-3 was rare and showed virus inside infiltrating mononuclear cells in a region where muscle tissue had been extensively destroyed. Persistent CVB1 occurred more frequently in severely diseased animals and in tissue sections displaying intense inflammation. Moreover, HPP-2 showed a stronger association with tissue inflammation and hindquarter weakness than did HPP-1. These data demonstrate that CVB1 persists in skeletal muscle for at least 28 to 31 days postinfection and support the concept that this persistence plays a role in the development of murine polymyositis.

Animals↗

PubMed1997

Neural and muscular electric activity in the cat's knee. Changes when the anterior cruciate ligament is transected.

We studied the response of the normal and unstable knee to passive motion and anterior tibial displacement in the cat. 6 cats were anesthetized and the deep level of anesthesia was controlled by electroencephalograms. We recorded electric activity in the articular nerves (posterior PAN and medial MAN) and periarticular muscles (quadriceps and hamstring), while performing passive flexion, extension, internal and external rotation. We then produced anterior displacement of the tibia at 30 degrees and 90 degrees of flexion, as in the Lachman and the anterior drawer maneuvers. The anterior cruciate ligament was surgically sectioned and the same series of passive displacements was performed. We observed statistically significant increased activity in the MAN, the PAN and the quadriceps muscle during knee flexion, in the MAN during extension, and in the PAN and hamstring during external rotation with the knee 90 degrees flexed. Anterior cruciate transection caused anterior displacement of the tibia during stress. This produced a significant increase in the MAN activity and a significant decrease in the hamstring electric activity at 30 degrees and 90 degrees of flexion, as in Lachman and anterior drawer maneuvers. We conclude that electric activity in the articular nerves and periarticular muscles, in response to passive motion and anterior tibial displacement, is altered in the cat's knee after anterior cruciate transection. This suggests that various patterns of periarticular muscle reaction in the anterior cruciate-deficient knee may be related to the unconscious perception of abnormal motion.

Animals↗

PubMed2000

Epidural electric stimulation of posterior structures of the human lumbar spinal cord: 1. muscle twitches - a functional method to define the site of stimulation.

OBJECTIVES: To describe an electrophysiological method for determining the relation between lumbar cord dorsal roots and cathode of epidural electrode for spinal cord stimulation (SCS). MATERIALS AND METHODS: Data has been collected from 13 subjects who have been under evaluation of effectiveness of SCS for control of spasticity. Induced muscle twitches from both quadriceps (Q), adductors (A), hamstrings (H), tibial anterior muscles (TA) and triceps surae muscles (TS) were simultaneously recorded with surface-electrode polyelectromyography (pEMG) and analyzed for amplitudes, latency times and recruitment order. RESULTS: Stimulation of dorsal lumbar cord structures evoked characteristic EMG events during muscle twitch responses. Their amplitudes varied with stimulus strength. Latency times were rather invariable regardless of stimulus strength. Two distinct recruitment orders were demonstrated depending on whether the stimulating cathode was placed over the upper (=response from quadriceps and/or adductor muscles) or the lower (=response from tibialis anterior and triceps surae) lumbar cord segments. The chances to stimulate upper lumbar cord segments are best around the 12th thoracic vertebra. CONCLUSIONS: pEMG recording of muscle twitches enables us to accurately differentiate between upper and lower lumbar cord segments. Furthermore, our findings regarding amplitude, latency and recruitment order strongly suggest that we stimulate posterior roots not posterior columns of the lumbar spinal cord.

Adolescent↗

PubMed1999

Anterior cruciate ligament reconstruction affects proprioception in the cat's knee.

To study the cat's knee after anterior cruciate ligament reconstruction, we compared its neural and muscular activity with that in the normal and the unstable knee. We recorded the electric activity in the articular nerves (posterior -PAN and medial -MAN) and periarticular muscles (quadriceps and hamstring) while performing passive flexion, extension, external and internal rotation, and also anterior translation of the tibia at 30 degrees and 90 degrees of flexion. The same series of maneuvers was performed in the same knees after surgical section of the anterior cruciate ligament and then after anterior cruciate reconstruction. The electric activity recorded in the reconstructed knee was compared to that in the same knee before surgery and in the same unstable knee after anterior cruciate section. We observed that the reconstructed knee, compared to the injured knee, showed a decrease in articular nerves and quadriceps activity while it regained stability. This decrease converged to the recordings in the normal knee. However, differences in MAN, PAN and hamstring activity were still present in the reconstructed knee. This suggests that, although anterior cruciate reconstruction seems beneficial for restoring articular nerve and periarticular muscle activities to a certain degree, proprioception in the reconstructed knee does not match that in the normal knee.

Action Potentials↗

PubMedDate not supplied

[Bilateral diabetic infarction of the thigh adductor muscles in a diabetic female patient-- A case report and review of the literature].

A 30-year-old female complained of lancinating pain in the bilateral thighs for 10 days. The patient had a 22-year history of insulin-dependent diabetes mellitus. Physical examination revealed swelling of the bilateral lower extremities. There was exquisite tenderness on palpation over the medial thighs, with marked increase in pain on hip and knee flexion. Muscle strength of quadriceps, hamstrings, and hip adductor was decreased due to muscle pain. Pedal pulses were palpable bilaterally. Roentogenograms of the left femur revealed calcification of the left femoral arterial wall. Venogram revealed no obstruction with normal drainage. Complete blood cell count showed left shift of the neutrophils, markedly accelerated erythrocyte sedimentation rate, prolonged prothorombin time of 9 sec (normal 11.7 sec), C-reactive protein of 7.3 mg/dl and serum creatine kinase level of 175 IU/L. FBS was 225 mg/dl and Hb A 1 c was 16.4%. An MR imaging of the thighs revealed high signal intensities in the bilateral adductor muscles on T 2-weighted images. The symptoms resolved spontaneously over a three week period. From the course of the illness and MR imaging, the patient was diagnosed having diabetic muscle infarction (DMI), a rare complication of diabetes mellitus. To our knowledge, this is the first reported case of DMI in Japan. Diabetic microangiopathy and hypercoagulability are thought to be responsible for inducing DMI. Because the diagnosis can be made from the characteristic clinical and the typical MR imaging findings, muscle biopsy is not always necessary to obtain the diagnosis of DMI.

Adult↗

PubMed1997

A musculoskeletal model of the knee for evaluating ligament forces during isometric contractions.

A model of the knee in the sagittal plane was developed to study the forces in the ligaments induced by isometric contractions of the extensor and flexor muscles. The geometry of the distal femur was obtained from cadaver data. The tibial plateau and patellar facet were modeled as flat surfaces. Eleven elastic elements were used to describe the mechanical behavior of the anterior and posterior cruciate ligaments (ACL and PCL), the medial and lateral collateral ligaments (MCL and LCL), and the posterior capsule. The model knee was actuated by 11 musculotendinous units, each muscle represented by a Hill-type contractile element, a series-elastic element, and a parallel-elastic element. Tendon was assumed to be elastic. The response of the model to anterior-posterior drawer suggests that the geometrical and mechanical properties of the model ligaments approximate the behavior of real ligaments in the intact knee. Calculations for a simulated quadriceps leg raise indicate further that the two-dimensional model reproduces the response of the three-dimensional knee under similar conditions of loading and constraint. During maximum isometric contractions of the quadriceps, the model ACL is loaded from full extension to 80 degrees C of flexion; the model PCL is loaded at 70 degrees of flexion and greater. For maximum isometric extension, ACL forces in the range 0-20 degrees of flexion depend most heavily upon the force-length properties of the quadriceps. At flexion angles greater than 20 degrees, cruciate ligament forces are determined by the geometry of the articulating surfaces of the bones. During isolated contractions of the hamstrings and gastrocnemius muscles, the model ACL is loaded from full extension to 10 degrees of flexion; the model PCL is loaded at all flexion angles greater than 10 degrees. Isolated contractions of the flexor muscles cannot unload the ACL near full extension, as the behavior of the ACL in this region is governed by the shapes of the bones. At 10 degrees of flexion or greater, the overall pattern of PCL force is explained by the force length properties of the hamstrings and by the geometrical arrangement of the flexor muscles about the knee.

Adult↗

PubMedDate not supplied

Surgical repair of complete proximal hamstring tendon rupture.

BACKGROUND: Complete proximal hamstring tendon rupture is a rare injury associated with significant functional loss. Nonoperative treatment has proven inadequate in returning patients to their previous activity level. PURPOSE: We wanted to describe the outcome of primary surgical repair of the proximal hamstring tendon avulsion. STUDY DESIGN: Retrospective cohort study. METHODS: Between 1994 and 1999, 11 patients (4 women and 7 men) with an average age of 41.5 years (range, 21 to 51) had a diagnosis of complete proximal hamstring tendon rupture based on mechanism of injury, physical examination, and radiographic assessment. All underwent a single operation followed by standard postoperative physical therapy. At the latest follow-up (average, 34 months), patients completed a questionnaire regarding such outcome parameters as pain, function, leg control, stiffness, return to activity, and overall satisfaction. RESULTS: Isokinetic muscle testing revealed an overall average of 91%return of hamstring muscle strength. Ten of 11 patients were satisfied with the result, and 7 of 9 athletically active patients were able to return to sport an average of 6 months (range, 3 to 10) after surgery. No difference between early and late repairs was identified in regard to functional outcome or return to sport. CONCLUSIONS: Satisfactory results can be achieved with both early and late hamstring tendon repairs in a majority of cases with surgical repair.

Adult↗