[Use of the anatomical cemented femoral stem SAS I: mid-term results]. / Zkusenosti s cementovaným anatomicky tvarovaným dríkem SAS I - strednedobé výsledky.

PURPOSE OF THE STUDY In view of increasing interest in a relationship between the surface of an implant and its behaviour and longevity in total hip arthroplasty (THA), the aim of this study is to present the clinical and radiographic results, as well as complications, of hip replacement surgery using the cemented femoral stem SAS I. MATERIAL AND METHODS A total of 298 cemented femoral stems SAS I were implanted in 275 patients at our department between 1996 and 2005. The patient average age was 72.1 years, with the range from 64 to 92 years. The pre-operative diagnoses were as follows: primary osteoarthritis in 179 (30.1%); post-dysplastic osteoarthritis in 41 (13.7%); femoral neck fracture in 44 (14.8%); avascular necrosis of the femoral head in 23 (7.7%); rheumatoid arthritis in nine (3%) and other causes in two (0.7%) patients. Of the 275 patients who had the surgery, 186 (204 THAs) underwent clinical and X-ray examination at an average follow-up of 11.5 years (range, 8 to 17 years). The clinical results were used to calculate the Harris hip score and radiographic evaluation was based on antero-posterior views. RESULTS The group of 186 assessed patients (204 THAs) comprised 106 women and 80 men, who were on average 85.4 years old on evaluation (range, 72 to 92 years). Of the remaining patients, 62 patients (64 THAs) died from causes unrelated to the surgery and 27 patients (30 THAs) were lost to follow-up. The functional outcome of surgery assessed by the Harris hip score was excellent in 61 (32.8%), good in 94 (50.5%), satisfactory in 26 (14%) and poor in five (2.7%) patients. The 93.1% SAS I stem longevity was recorded in relation to aseptic loosening; reimplantation for this indication was performed in 14 THAs. No revision surgery for failure due to valgus/varus deviations of the stem was carried out. Of the 204 hips, 188 had femoral stems aligned in neutral, 12 (5.9%) in valgus and four (2%) in varus positions. DISCUSSION The anatomical femoral stem SAS I is an implant made to fit the proximal femur anatomy. Its highly polished surface allows for optimal fitting with the supporting bone and for even distribution of weight bearing. This results in a low rate of THA failure. In accordance with the relevant literature, the acetabular components is considered to be the weakest element in total hip replacement in terms of aseptic loosening and implant failure. At present, the SAS I stem has no Morse Eurocone taper and this is the chief obstacle hindering its more frequent use in endoprosthetics. CONCLUSIONS The results of our study are in agreement with those of other successfully implanted polished cemented femoral components. Key words: anatomical cemented femoral component, surface adjustment of the femoral stem, complications.

[Treatment of trochanteric fractures by percutaneous compression plate]. / Osetrení trochanterických zlomenin PC.C.P. dlahou.

PURPOSE OF THE STUDY: To present a new type of percutaneous compression plate (PCP) for a minimally invasive method of treating trochanteric hip fractures. MATERIAL: Between September 2004 and December 2006, a total of 66 patients with hip fractures were treated by minimally invasive percutaneous osteosynthesis involving a PCP. The average age of the patients was 74.5 years (range, 27-95 years). The fractures were classified as pertrochanteric (AO31, A1.1-A2.3) in 73%, femoral neck fracture (AO31, B2) in 20%, and intertrochanteric fracture (AO31, A3.1) in 7% of the patients. METHODS: Reduction was performed under conduction or general anaesthesia on a traction table, using an X-ray image intensifier system. Reduction and intra-operative temporary stabilisation of the fracture was facilitated by a posterior reduction device. Access was gained and a PCP was inserted through two incisions at the lateral side of the proximal femur. RESULTS: The patients were followed up for at least 6 months. Radiographic union was found on average at 3 months post-operatively. No pseudoarthrosis or implant failure was recorded. At 6-month follow-up, 81% of the patients were able to walk without walking aid or with one walking cane only. Two crutches were used by 8% of the patients.To walk without help was impossible for 11% of the patients whose mobility had already been limited before the injury. DISCUSSION: PCP osteosynthesis for trochanteric fractures is a novel minimally invasive approach providing a better treatment of the fracture. Compared to dynamic hip screw osteosynthesis used before, PCP allows for earlier weight bearing and noticeably reduces blood loss. Implant construction as well as post-operative controlled impaction of the fracture minimize the risk of osteosynthesis failure. The simple instrumentation construction enables us to reduce operative time. CONCLUSIONS: The percutaneous compression plate is a contribution to minimally invasive osteosynthesis of trochanteric fractures. An increase in rotational stability of the implant due to its biaxial telescopic construction allows for earlier weight-bearing of the extremity, thus facilitating the patient's earlier return to everyday life activities. It also reduces operative trauma, blood loss and post-operative complications.

[Tenodesis for the treatment of chronic instability of the radioulnar joint]. / Tenodéza - resení chronické nestability distálního radioulnárního kloubu.

PURPOSE OF THE STUDY Distal radioulnar joint (DRUJ) instability often develops after distal forearm fracture or severe dislocation of the wrist with damage to its stabilising structures. The instability is usually diagnosed as a chronic condition and only rarely at the time of injury. When the stabilising structures are not treated adequately soon after injury, instability develops and is accompanied with pain, restricted range of motion and reduced grip strength. This study presents the option of chronic instability treatment by tenodesis with use of the palmaris longus tendon. Its aim is to remind the broad medical community of this issue. MATERIAL Between July 1994 and November 2000, tenodesis was performed in 15 patients with chronic DRUJ instability. The right and left sides were affected in 10 and five patients, respectively; of them 12 were dominant extremities. All injuries were diagnosed as dorsal subluxation of the ulnar head, with side dislocation in three patients. METHODS The diagnosis was based on a thorough medical history, and clinical and radiographic examination, including projections in forced maximum radial and ulnar duction, as recommended by Geyer and Luzius as early as in 1964. Tenodesis was done by the Jäger and Wirth method using the palmaris longus tendon. The patients were scored according to the Modified Mayo Wrist System. RESULTS Of the 15 patients treated by this method, 14 were evaluated. Eight patients regarded the results as very good, with no pain at maximal physical activity, and five considered them good, experiencing pain only at maximal but not at everyday activities. One patient reported a poor outcome. The average score increased from pre-operative 40 to 60 points post-operatively. All patients had a slight restriction of rotation movements of the forearm. Residual instability was found in one patient. DISCUSSION It is a common view that this condition is caused by subluxation or dislocation of the ulnar head, while in fact it is subluxation or dislocation of the radius turning around the ulna. As reported in the literature, dorsal dislocation is three-times as frequent as volnar dislocation, and this is in agreement with our findings. There is a wide variety of the operative methods for tenodesis which differ in the distribution of tunnels in bone. Restriction of the range of motion in our patients also agreed with the literature data. No effect of a distal radius fracture on the results of surgery was recorded. CONCLUSIONS Our results show that tenodesis is a method suitable to treat chronic DRUJ instability if the indication criteria are observed, i. e., if no arthritic lesions are present in the joint.

Central analgesic actions of loperamide following transient permeation of the blood brain barrier with Cereport (RMP-7).

The bradykinin analog, Cereport (RMP-7), was designed to increase permeability of the blood brain barrier (BBB). Over the past several years it has been developed primarily as a means of increasing permeability of the blood brain tumor barrier, where early evidence indicated a particularly robust and reliable effect. The present series of experiments were intended to determine whether Cereport might also be used to increase delivery of pharmacological agents across the normal (i.e., non-tumor) BBB. This was accomplished by testing the ability of Cereport to enhance delivery of the peripherally acting opiate agonist, loperamide, to the brain, as evidenced by induction of a centrally mediated analgesic effect. Intravenous administration of a combination of Cereport and loperamide produced a significant analgesic effect (2-fold increase in response times) when animals were tested on a hotplate apparatus. Loperamide alone did not produce analgesia. An analysis of the time course of analgesia revealed a graded onset of analgesia which peaked at 30 min, maintained asymptote at 60 min, and began to diminish by 120 min following Cereport and loperamide administration. Finally, the analgesic effects of combining Cereport and loperamide were completely blocked when animals were pre-treated with the opiate antagonist naloxone, demonstrating that the analgesia was mediated through opiate receptors. Collectively, these results suggest that Cereport was able to increase delivery of loperamide across the BBB, allowing it to gain access to opiate receptors in the CNS to produce a centrally mediated analgesic effect. They therefore provide clear evidence that safe and well-tolerated doses of Cereport can increase permeability of the normal (i.e., non-tumor) BBB. Moreover, they provide the first evidence of a pharmacological effect specifically enabled by controlled (i.e., receptor-mediated) modulation of the BBB.

Formation of 1,10-disubstituted benzo

The first 1,10-heterodisubstituted benzo[c]cinnoline derivative 1 was prepared from the trinitrobiphenyl 2. Investigation of the mechanism of ring closure in 2, 5, and 8 revealed a complex reduction-oxidation-cyclization sequence. The mechanism is discussed in light of the stereoelectronic demands of the substituent functionalities. Benzo[c]cinnoline derivative 1 [C15H15N3S, monoclinic, P2(1)/c: a = 7.4063(3) A, b = 10.3739(5) A, c = 16.7642(8) A, beta = 91.816(1) degrees, Z = 4] and its 5-N-oxide 7(N5) [C18H18N3OS, triclinic, Pi: a = 8.1510(7) A, b = 8.6106(7) A, c = 12.102(1) A, alpha = 86.262(1) degrees, beta = 83.364(1) degrees, gamma = 74.711(1) degrees, Z = 4] were structurally characterized and showed a significant helical distortion of the heterocyclic ring. Oxidation of 1 with NCS or triamine 12 with PhI(OAc)2 led to a new heterocyclic ring system, ylide 13. Both benzo[c]cinnoline 1 and ylide 13 were characterized spectroscopically and the absorption spectra were correlated with the results of ZINDO calculations.

Biomechanical effects of functional knee bracing. Practical implications.

Bracing of the anterior cruciate-deficient knee remains controversial. Close review of published data has revealed enough common observations about braces that strong suggestive information can be utilised for clinical purposes until more concrete data are provided. Brace function can vary with design. The primary differences noted are between the shell-type and strap-type braces. Shell braces tend to provide more stability to the knee than do the strap braces. Proper hinge placement, rather than type, affects pistoning and overall performance of the brace. Custom braces provide a better fit than off-the-shelf devices, but they can feel more restrictive, especially the shell braces. Static bench-testing data have shown that these braces provide little stability against anterior tibial translation at forces comparable to athletic play. Yet kinematic and force plate data suggest that they may produce some mechanical constraining effect to the entire lower extremity instead of just the knee joint. The literature still supports the philosophy that functional bracing should be considered as part of a comprehensive rehabilitation programme for an anterior cruciate-deficient athlete with significant functional deficits.

Powder Structure Solutions of the Compounds Potassium Phenoxide-Phenol: C(6)H(5)OK.xC(6)H(5)OH (x = 2, 3).

We report the ab initio structure solutions of two solvent containing potassium phenoxides by high-resolution powder X-ray diffraction. Both compounds are of interest for the classification of the mechanism of Kolbe-Schmitt type reactions. C(6)H(5)OK.2C(6)H(5)OH crystallizes in space group Abm2, Z = 4, with unit cell parameters a = 10.12458(4) Å, b = 21.2413(1) Å, c = 7.89784(3) Å. C(6)H(5)OK.3C(6)H(5)OH crystallizes in space group Pbca, Z = 8, with unit cell parameters a = 22.7713(1) Å, b = 25.4479(2) Å, c = 7.75549(4) Å. Both compounds show polymeric zigzag chains [K([6])O(2)([2])O([1])pi(phenyl)([1])] aligned along the c-axis. The coordination of the potassium ions is similar for both compounds. They lie at the center of distorted octahedra of five oxygen atoms and one phenyl ring, which donates its pi electrons. The distortion decreases as the number of free phenol increases.

Non-operative treatment of ruptures of the anterior cruciate ligament in middle-aged patients. Results after long-term follow-up.

We retrospectively reviewed the records of fifty-two patients who had had a rupture of the anterior cruciate ligament between the ages of forty and sixty years, to determine the results of aggressive non-operative treatment. We were able to locate and re-examine thirty of these patients (mean age, forty-six years) after a mean duration of follow-up of seven years (range, five to thirteen years), and to assess the clinical, radiographic, and functional results. The mean score, according to the scale of Lysholm and Gillquist, was 82 points; eight of the eleven patients who had combined ligamentous injuries had a score of less than 84 points (symptoms with daily activities). Thirteen substantial reinjuries had occurred in eleven patients (37 per cent) during the follow-up period. Twenty-nine patients (97 per cent) had a grade-2 or 3 Lachman test, and a positive pivot-shift test was elicited in twenty-five patients (83 per cent). Plain radiographs revealed minimum or no changes in twenty-six patients (87 per cent). Magnetic resonance imaging in nine patients revealed scarring of the remnant of the anterior cruciate ligament to the posterior cruciate ligament in six. The mean difference in anterior-posterior laxity between the injured knee and the normal, contralateral knee, as measured with the KT-1000 arthrometer, was five millimeters at twenty pounds (eighty-nine newtons). Twenty-five (83 per cent) of these thirty middle-aged patients, who had had guided rehabilitation and had modified activity, had a satisfactory outcome without an operation. However, a few patients, who had combined instabilities and who wished to resume competitive sports activity that required pivoting, were dissatisfied. Such patients may need operative reconstruction to achieve their goals.

Medial instability of the elbow in throwing athletes. Treatment by repair or reconstruction of the ulnar collateral ligament.

From September 1974 to December 1987, seventy-one patients were operated on for valgus instability of the elbow. The average length of follow-up of sixty-eight patients (seventy operations) was 6.3 years (range, two to fifteen years). At the operation, a torn or incompetent ulnar collateral ligament was found. Fourteen patients had a direct repair of the ligament, and fifty-six had a reconstruction of the ligament using a free tendon graft. The result was excellent or good in ten patients in the repair group and in forty-five (80 per cent) in the reconstruction group. Seven of the fourteen patients who had a direct repair returned to the previous level of participation in their sport. Of the fifty-six who had a reconstruction, thirty-eight (68 per cent) returned to the previous level of participation. Twelve of the sixteen major-league baseball players who had a reconstruction as the primary operation (no previous operation on the elbow) were able to return to playing major-league baseball, and two of the seven major-league players who had a direct repair returned to playing major-league baseball. Previous operations on the elbow decreased the chance of returning to the previous level of sports participation (p = 0.04). Fifteen patients had postoperative ulnar neuropathy. This was transient in six patients, only one of whom was unable to return to the previous level of sport. The other nine patients had an additional operation for the neuropathy; four were able to return to the previous level of sport.

Dynamic EMG analysis of torque transfer in professional baseball pitchers.

Fifteen professional baseball pitchers underwent active pitching motion analysis of the abdominal oblique, rectus abdominis, lumbar paraspinous and gluteus maximus muscles bilaterally via surface electrode evaluation. Baseline resting and isometric maximum values were obtained and active data referenced against these for comparison. The muscle activity then was measured during the pitching sequence and analyzed in each of the five pitching phases. The abdominal oblique, lumbar paraspinous and rectus abdominis contralateral to the pitching arm and the ipsilateral gluteus maximus all had increases in activity level of 75 to 100% during the active pitching motion. Using these data indicating specific muscle group patterns with clinical and performance data, we hope to minimize injuries and maximize pitching performance.

Muscular control of the ankle in running.

The purpose of this study was to describe and compare the muscle firing patterns of the muscles controlling the ankle during running. Fine-wire electrodes monitored the activity of the gastrocnemius, soleus, peroneus brevis, tibialis posterior, and tibialis anterior muscles during 3 paces of running. High-speed film was used to synchronize the electromyographic data with the phases of running. The subjects were 15 recreational and competitive runners who were injury-free. There were 3 significant findings. First, the firing patterns of all of the posterior muscles demonstrated peak activity during midstance phase. Thus, these muscles were contracting in an eccentric fashion to control ankle dorsiflexion as the center of gravity passed over the ankle. Second, the tibialis anterior muscle fired above the fatigue threshold for 85% of the time. This may account for the high number of fatigue-related injuries to the tibialis anterior muscle seen in runners. Third, there was a significant increase of activity in the peroneus brevis muscle as the pace increased. This indicates the importance of training this muscle when pace is increased. Using this information, a sport-specific effective and efficient exercise program for runners can be developed.

Electromyographic shoulder activity in men and women professional golfers.

Men and women both enjoy the game of golf. Special considerations are made for women, such as the courses on the professional tours. Thus, one can ask what differences might exist between men and women golfers. This study compares the electromyographic firing patterns of normal shoulder musculature in men and women professional golfers. Eight shoulder muscles (pectoralis major, latissimus dorsi, supraspinatus, infraspinatus, subscapularis, anterior, middle and posterior deltoids) were studied using indwelling electromyography. A visual analysis revealed that women tended to have slightly more activity during the takeaway and forward swing phases, and the men tended to have more activity during acceleration and follow-through. However, an independent two-tailed t-test (P = 0.05) showed these differences not to be statistically significant. This finding is in keeping with injury incidence data from the LPGA Tour, PGA Tour, and Senior PGA Tour, which showed that all three tours have a similar incidence of shoulder injuries. This study does not compare the relative strength of men and women, however.

Electromyographic analysis of the shoulder during the golf swing.

Golf is a popular sport throughout the world, yet there is little in the literature that discusses the mechanics of the swing. The purpose of this study is to analyze the EMG activity in eight shoulder muscles of both the right and left arms during the golf swing. The results reveal that the infraspinatus and supraspinatus act predominantly at the extremes of shoulder range of motion, the subscapularis and pectoralis major during acceleration, the latissimus dorsi during forward swing, and the anterior deltoid during forward swing and follow-through. The middle and posterior deltoids appear to be relatively noncontributory, without any specific timing patterns. This data is an expansion of an earlier pilot study and allows us to more accurately develop an exercise program for optimal performance as well as for prevention and rehabilitation.

Electromyographic analysis of the trunk in golfers.

Golf is a popular sport for both men and women. The trunk is the most common area of injury during the golf swing. The purpose of this study was to describe and compare the muscle firing patterns in the trunk during the golf swing. Twenty-three golfers with handicaps of five or below volunteered for this study. Surface electromyographic electrodes were placed on the abdominal oblique and erector spinae muscles bilaterally. High-speed cinematography was used in conjunction with the electromyographic electrodes. The results demonstrated relatively low activity in all muscles during takeaway (below 30% of maximal muscle test), and relatively high and constant activity throughout the rest of the swing (above 30% maximal muscle test, with the exception of the contralateral erector spinae during late follow-through, which was 28% maximal muscle test). This high and constant activity demonstrated the importance of the trunk muscles during a golf swing. These results indicate the need for an effective preventive and rehabilitative exercise program for the golfer.

Electromyographic analysis of hip and knee musculature during running.

The purpose of this study was to describe the firing pattern of 11 hip and knee muscles during running. Thirty recreational runners volunteered to run at 3 different paces with indwelling electromyographic electrodes while being filmed at 100 frames per second. Results demonstrated that medial and lateral vasti muscles acted together for knee extension during terminal swing and loading response, possibly providing a patella stabilizing role. The vastus intermedius muscle functioned with the other vasti, plus eccentrically controlled knee flexion during swing phase. The rectus femoris muscle fired with the vastus intermedius muscle and assisted the iliacus muscle with hip flexion. The hamstrings fired primarily to eccentrically control hip flexion. The adductor magnus, tensor fascia lata, and gluteus maximus muscles afforded pelvic stabilization while assisting with hip flexion and extension. Forward propulsion was provided mainly by hip flexion and knee extension, which is contrary to the view that posterior calf muscles provide propulsion during toe off. Faster running paces lead to increased activity in the muscles. This may lead to more injuries, primarily in the muscles that were contracting eccentrically.

The normal shoulder during freestyle swimming. An electromyographic and cinematographic analysis of twelve muscles.

The shoulder in swimming is subjected to multiple factors that can lead to a high injury rate. To prevent injury, one must understand the biomechanics of swimming. This paper describes the electromyographic and cinematographic findings of 12 shoulder muscles in competitive swimmers without shoulder pain. The results show the three heads of the deltoid and the supraspinatus functioning in synchrony to place the arm at hand entry and exit, the rhomboids and upper trapezius to position the scapula for the arm, the pectoralis major and latissimus dorsi to propel the body, the subscapularis and serratus anterior as muscles with constant muscle activity, the teres minor functioning with the pectoralis major, and the infraspinatus active only to externally rotate the arm at midrecovery. This information is important to design optimal preventative and rehabilitative exercise programs.

Functional anatomy of the flexor pronator muscle group in relation to the medial collateral ligament of the elbow.

To describe the relationship of the pronator teres, flexor carpi radialis, flexor digitorum superficialis, and flexor carpi ulnaris muscles to the medial collateral ligament at 30 degrees, 90 degrees, and 120 degrees of elbow flexion, we dissected 11 cadaveric specimens. The flexor carpi ulnaris muscle is the predominant musculotendinous unit overlying the medial collateral ligament in the majority of cases and is the only one at 120 degrees of elbow flexion. The flexor digitorum superficialis muscle is the only other significant contributor. The medial collateral ligament is the primary stabilizer of the medial elbow with elbow flexion greater than 30 degrees, as in throwing. The flexor carpi ulnaris muscle, because of its position directly over the medial collateral ligament, and the flexor digitorum superficialis muscle, with its near proximity and relatively large bulk, are the specific muscles best suited to provide medial elbow support. This is especially relevant to overhand throwing athletes who encounter extreme valgus force across the elbow during the cocking and acceleration phases of the throwing motion. Exercise and conditioning of the medial elbow musculature, specifically the flexor digitorum superficialis muscle and the flexor carpi ulnaris muscle, may prevent injury or assist in rehabilitation of medial elbow instability, especially in overhand throwing athletes.

Electromyographic analysis of the scapular muscles during a golf swing.

To describe the role of the scapular muscles in the golf swing, we studied 15 competitive male golfers. Four muscles were studied bilaterally using dynamic electromyography and cinematography. In the trailing arm, the levator scapulae elevates while the rhomboid muscles retract the scapula during takeaway; both then stabilize the scapula through the remainder of the swing. In the leading arm, these muscles retract the scapula during forward swing and acceleration. The trapezius muscle in the trailing arm also demonstrates high activity during takeaway to aid in scapular retraction. In the leading arm, trapezius activity is high in forward swing and through the remainder of the swing to promote scapular retraction. The serratus anterior muscle activity is high in the trailing arm during forward swing and through the remainder of the swing to maximize scapular protraction. In the leading arm, the serratus anterior muscle has constant activity through all phases of the swing, which may explain the clinical scenario of muscle fatigue in high demand golfers. The golf swing and uncoiling action requires that the scapular muscles work in synchrony to maximize swing arc and clubhead speed. This study demonstrates the importance of the scapular muscles in the golf swing and the need for specific strengthening exercises.

Electromyographic analysis of the glenohumeral muscles during a baseball rehabilitation program.

Many exercises are used to strengthen the glenohumeral muscles, but there have been limited studies to evaluate the exercises. Thus, the purpose of this study was to decide how the muscles responsible for humeral motion can best be exercised in a rehabilitation program for the throwing athlete. Dynamic, fine wire, intramuscular electromyography was carried out in 15 normal male volunteers performing 17 shoulder exercises derived from a shoulder rehabilitation program used by professional baseball clubs. The four rotator cuff muscles were studied, as well as other positioners of the humerus, including the pectoralis major, latissimus dorsi, and three portions of the deltoid. The electromyographic activity was synchronized with cinematography and averaged over 30 degrees arcs of motion. An exercise was considered to be a significant challenge for a muscle if it generated at least 50% of its predetermined maximum contraction over three consecutive arcs (i.e., a 90 degrees range). Four exercises were consistently found to be among the most challenging exercises for every muscle. These shoulder exercises consisted of 1) elevation in the scapular plane with thumbs down, 2) flexion, 3) horizontal abduction with arms externally rotated, and 4) press-up. This study documents that the minimum for an effective and succinct rehabilitation protocol for the glenohumeral muscles would include these exercises.

An electromyographic analysis of the knee during functional activities. I. The normal profile.

This study describes the fine-wire electromyographic profile of the normal knee. Twenty-two subjects with no prior history of knee injury volunteered for the study. Each subject had fine-wire electromyographic evaluation of 8 muscles (vastus medialis oblique, vastus lateralis, rectus femoris, semimembranosus, biceps femoris, tibialis anterior, gastrocnemius, and soleus muscles) while performing 7 functional activities. The percentage of maximum manual test for each muscle during each phase of the activities was used to determine means and standard deviations for the group. Walking and ramp and stair ascending and descending produced similar electromyographic profiles. Running and cross-cutting demonstrated unique electromyographic profiles with an overall higher muscle activity than the previous 5 activities. A quadriceps-hamstrings muscles' coordinated response was identified consistently in each activity. These findings illustrate the integral nature of each of the 8 examined muscles in knee motion. Furthermore, this study demonstrates a coordinated response of quadriceps-hamstrings muscles in the normal knee and may more thoroughly define the coordinated activity of these 2 antagonist muscle groups. Finally, this study provides a framework within which various knee conditions can be compared and from which specific rehabilitation recommendations can be generated.