Notes: Sixty 60-day-old Sprague-Dawley male rats were subjected to exhaustive and non-exhaustive exercise treatment over a period of 3, 5 and 7 weeks. Moderate exercise consisted of running on the treadmill at 10% grade at 10 m/min for 20 min for 5 days per week, while exhaustive running consisted of running at 10% grade at 15 m/min with an increase of 5 m/min every 5 min for 5 days per week. Half of the exercised rats were subjected to immersion in 4°C water for 5 min after each exercise bout. Histological analyses of the gastrocnemius showed that ultrastructural damage of myofibrils occurred after 5 weeks of exhaustive running and 7 weeks of moderate running. With post-exercise immersion in 4°C water for 5 min, the occurrence of ultrastructural damage advanced by 2 weeks in both treatments. It was concluded that the application of cryotherapy to the exercise groups was deleterious. Muscle damage occurred earlier in the treatment group and the degree of damage was also more serious over the same time period. This study supports the recommendation that the use of cryotherapy to reduce pain and haematoma formation should be coupled with rest for at least 48 hours.

Notes: Abstract This study was undertaken to evaluate knee proprioception in patients with isolated unilateral posterior cruciate ligament (PCL) injuries. Eighteen subjects with isolated PCL tears were studied 1–234 months after injury. The threshold to detect passive motion (TTDPM) was used to evaluate kinesthesia and the ability to passively reproduce passive positioning (RPP) to test joint position sense. Two starting positions were tested in all knees: 45 ° (middle range) and 110 ° (end range) to evaluate knee proprioception when the PCL is under different amounts of tension. TTDPM and RPP were tested as the knee moved into flexion and extension from both starting positions. A statistically significant reduction in TTDPM was identified in PCL-injured knees tested from the 45 ° starting position, moving into flexion and extension. RPP was statistically better in the PCL-deficient knee as tested from 110 ° moving into flexion and extension. No difference was identified in the TTDPM starting at 110 ° or in RPP with the presented angle at 45 ° moving into flexion or extension. These subtle but statistically significant findings suggest that proprioceptive mechanoreceptors may play a clinical role in PCL-intact and PCL-deficient patients. Further, it appears that kinesthesia and joint position sense may function through different mechanisms.

Notes: Abstract Peroneal nerve palsy following knee dislocation is a serious problem, and neurolysis at the time of knee reconstruction does not always result in return of peroneal nerve function. We describe peroneal nerve pathoanatomy in three patients in whom late exploration of the peroneal nerve was performed because of ongoing absence of ankle dorsiflexion. We identified frank nerve rupture in two patients and a lengthy neuroma in continuity in one which extended far proximal to the fibular head and well above the previous surgical incision used for peroneal nerve neurolysis at the time of knee reconstruction. In light of the current state of microneural surgery and the potential to reconstruct nerve defects, we discuss how our findings impact on treatment, and provide recommendations which may improve recovery of peroneal nerve function in future cases.

Notes: Abstract The role of proprioception as a protective mechanism has gained interest in recent years. From the clinical standpoint, several studies have dealt with ways to enhance proprioception following surgery and during rehabilitation. If kinesthesia (ability to detect passive motion) can be enhanced as a consequence of long-term athletic training, such training must be included as a part of the rehabilitation process to protect the patient from reinjury. Consequently, the purpose of this study was to compare the kinesthetic knee pattern between trained gymnasts and healthy nongymnasts. The proprioception testing device (PTD) was used to evaluate knee kinesthesia. From 45° of flexion, the knee was passively extended with the PTD. The device was stopped by the subject when this passive motion was detected. Fifteen healthy college-age female gymnasts (mean age 19.3 years) and 30 normal volunteers (mean age 20.7 years) comprised our study sample. A one-way analysis of variance (ANOVA) was used to compare the mean values of the dominant gymnastic knee to the dominant knee in the control group. Results revealed statistically significant mean differences between the trained gymnastic group and the untrained control group (F 1.34 (.95)=7.17.P=0.011). The results of this study suggest that extensive training has a positive influence on knee kinesthesia in addition to increasing muscle tone. According to the findings of this and other studies, highly trained athletes possess enhanced neurosensory pathways which are speculated to develop as a result of long-term athletic training. Although definite conclusions cannot be made from our investigation, prospective studies can determine the true role of athletic training in proprioceptive patterns.

Notes: Abstract Approximately 44% of patients develop osteoarthritis (OA) following rupture of the anterior cruciate ligament (ACL) if the injury is left unrepaired. Restoring knee stability through reconstruction, while providing symptomatic relief, has not been shown to reduce the incidence of degenerative changes. In fact, recent studies have shown that 50%–60% of ACL-reconstructed patients go on to develop degenerative changes or frank osteo-arthritis. In light of these data, our group suggests that the cause of post-traumatic osteoarthritis is not biomechanical but biochemical. To test this hypothesis, we measured levels of nine cytokines which are important in modulating physiological and pathophysiological metabolism of cartilage in knee joint synovial fluid following ACL rupture. Our patient population contained both acute und chronic ACL ruptures. A total of 84 samples were collected and analyzed by enzyme-linked immunosorbent assay. On the basis of the data collected, we were able to identify subgroups of patients who, on the basis of their synovial fluid cytokine profile, may be at greater or leasser risk of developing post-traumatic OA. In general, patients displayed concentrations of interleukin-1α (IL-1α), basic fibroblastic growth factor (bFGF), transforming growth factor-β (TGF-β), granulocyte/macrophage-colony stimulating factor (GM-CSF), IL-6, and IL-8 that we interpreted as being consistent with an inflammatory reaction. Of great interest is the fact that the levels of these cytokines were very similar in patients 4 weeks after injury and in chronic patients, leading us to hypothesize that a chronic smoldering inflammatory reaction persists after resolution of the acute effusion. This chronic inflammatory reaction could be the cause of cartilage degeneration seen in patients after ACL reconstruction. Furthermore, this study identified two distinct subpopulations of patients with dramatically differing levels of IL-1β and TNF-α in their synovial fluids. IL-1β and TNF-α were either high acutely and decreased to moderate levels over time, or they were zero acutely and remained zero or low. This is likely to be a very important observation as these two cytokines are key components of the inflammatory response and are the main intra-articular cytokines that provoke cartilage loss. It is our hypothesis that the group with high levels of IL-1β and TNF-α contains the 50%–60% of the patient population which goes on to develop OA, despite knee stabilization with ACL reconstruction. Conversely, we suggest that the group whose synovial fluid contains no IL-1β or TNF-α is protected from developing OA post-traumatically. IL-1-receptor antagonist protein (IRAP), the cytokine that antagonizes the biological effects of IL-1, was present acutely in our patient population; however, it was undetectable in chronic ACL-deficient knees. These data suggest the loss with time of an important cartilage-protective cytokine. The lack of IRAP chronically may allow IL-1β to act in an unrestrained manner resulting in cartilage loss. In addition, IL-1β promotes the secretion of many other inflammatory cytokines which may result in the chronic smoldering inflammatory reaction referred to above. These data encourage further study of the evaluation of cytokine concentrations in the ACL-deficient joint as a means of obtaining both prognostic and mechanistic information of clinical value to the physician.

Notes: Abstract Normal joint conditions are altered during arthroscopic surgery, and these changes have uncertain ultrastructural and biomechanical effects on articular cartilage. Experimental studies have shown that temperature variations affect the biomechanical properties of articular cartilage. We documented the temperature of the knee joint in 40 patients at the beginning and end of an arthroscopic procedure (anterior cruciate ligament reconstruction or meniscectomy). The intra-articular measurements were obtained using a digital thermometer connected to a sterile stainless steel probe. Correlation coefficients and linear regression techniques were used to determine which variables are independent predictors of joint temperature at the end of surgery. The mean knee joint temperature before surgery was 35.1°±1.0°C and at the end of surgery 24.6°±1.5°C. The joint temperature at the end of surgery was significantly affected by the temperature of the saline irrigant used and the length of arthroscopic procedure. The clinical implications of our findings must be clarified in animal models.

Notes: Abstract In this study, the geometric and mechanical properties of the long head of the biceps tendon were determined in order to elucidate its role in shoulder stability. We used a laser-micrometer system to measure the cross-sectional area and shape of seven fresh-frozen tendons at three levels: proximal, middle, and distal levels. The cross-sectional areas were found to be 22.7±9.3 mm2, 22.7±3.5 mm2, and 10.8±2.7 mm2, respectively. While statistically significant differences could not be demonstrated between the magnitudes of the areas, a consistent difference in shape was noted between the proximal and middle levels, the tendon being flatter as it progressed over the humeral head and more triangular as it passed through the bicipital groove. We then performed cyclic relaxation tests and uniaxial tensile testing of the tendons which revealed a cyclic stress relaxation of 18±4% over ten cycles. All tensile failures occurred within the midportion of the tendon substance. Additionally, the modulus was calculated between 3% and 6% strain and found to be 421±212 MPa, while the ultimate tensile strength, ultimate strain, and strain energy density were 32.5±5.3 MPa, 10.1±2.7%, and 1.9±0.4 MPa, respectively. These mechanical properties of the long head of the biceps tendon are of the same order of magnitude as tendons from other joints. The high stiffness of this tendon indicates that it has an ability to support the large load transferred to it by the muscle and to act as a humeral head depressor.

Notes: Abstract The Bankart lesion of the shoulder has long been associated with anterior instability. Our laboratory has developed a biomechanical model of the human shoulder which was used to determine the effects of creating a Bankart lesion on cadaveric specimens and then to compare the effects of two repair techniques. The model simulates the abducted, externally rotated position of the glenohumeral joint and uses pneumatic cylinders to simulate the rotator cuff forces. Specimens were tested intact following a partial Bankart lesion, following a complete Bankart lesion, and after performing a Bankart repair using three Mitek suture anchors. Finally, both the traditional and Mitek repairs were tested until failure. Strain in the inferior glenohumeral ligament (IGHL) and torque resistance was measured as an indication of instability of the joint. Strain was noted to decrease with increasing depth of lesion of the IGHL. Torsional rigidity of the shoulder decreased with increasing depth of lesion as well. Repairing the shoulder restores the strain and rigidity to control conditions. The mean load until failure was greater with the traditional repair than with the suture anchor technique. This study quantitates the effects of a Bankart lesion of the shoulder, and demonstrates that repairing the lesion with a suture anchor technique restores the biomechanics of the shoulder.

Notes: Abstract For the orthopedic sports medicine physician soft tissue injuries often present the greatest clinical problems. Not only do many of the most frequently injured tissues, such as the cruciate ligaments and articular cartilage, have very limited capabilities for spontaneous repair, but they also respond poorly to surgical or nonsurgical intervention. In this article we try to define the role of growth factors in these conditions and to outline concepts for future treatment based upon modulation of the native repair response. We suggest that gene transfer could improve the management of such injuries, particularly when used as vehicles for the targeted delivery of growth factors. The concept of gene therapy in orthopedic sports medicine can be extended to include disorders that present as laxity or mechanical weakness of ligaments. We speculate that subtle genetic differences between individuals may account for those who appear to be injury prone. In these cases it is likely that genes encoding the structural macromolecules of the matrix are defective. Local gene supplementation in such cases could be useful in the future.

Notes: Abstract Radiographic enlargement of bone tunnels following anterior cruciate ligament (ACL) reconstruction has been recently introduced in the literature; however, the etiology and clinical relevance of this phenomenon remain unclear. While early reports suggested that bone tunnel enlargement is mainly the result of an immune response to allograft tissue, more recent studies imply that other biological as well as mechanical factors play a more important role. Biological factors associated with tunnel enlargement include foreign-body immune response (against allografts), non-specific inflammatory response (as in osteolysis around total joint implants), cell necrosis due to toxic products in the tunnel (ethylene oxide, metal), and heat necrosis as a response to drilling (natural course). Mechanical factors contributing to tunnel enlargement include stress deprivation of bone within the tunnel wall, graft-tunnel motion, improper tunnel placement, and aggressive rehabilitation. Graft-tunnel motion refers to longitudinal and transverse motion of the graft within the bone tunnel and can occur with various graft types and fixation techniques. Aggressive rehabilitation programmes may contribute to tunnel enlargement as the graft-bone interface is subjected to early stress before biological incorporation is complete. Further basic research is required to verify the effect of the various proposed factors on the etiology of bone tunnel enlargement. We recommend that routine follow-up examinations after ACL reconstruction should include the measurement of bone tunnel size in order to contribute to a better understanding of the incidence, time course, and clinical relevance of this phenomenon. Improved and more anatomical surgical fixation techniques may be useful for the prevention of bone tunnel enlargement.