Nerve supply of the human knee and its functional importance

Localized synovial hypertrophy in the anteromedial compartment of the osteoarthritic knee

PURPOSE

The purpose of this study was to investigate the clinical and arthroscopic findings of osteoarthritis (OA) of the knee with localized synovial hypertrophy in the anteromedial compartment and the clinical results of arthroscopic partial synovectomy.

TYPE OF STUDY

Retrospective case series.

METHODS

We treated 19 osteoarthritic knees with localized synovial hypertrophy in 19 patients by arthroscopic partial synovectomy under local anesthesia. All patients had complained of knee pain (mechanical type pain) and catching sensations preoperatively. Preoperative diagnosis based on physical findings and imaging studies was a medial meniscus tear with medial OA in all patients. The mean follow-up was 37 months (range, 28 to 46 months). Clinical results were assessed with the Hospital for Special Surgery (HSS) scoring scale, overall subjective estimation, and patient satisfaction.

RESULTS

The catching sensation resolved immediately after surgery in all patients. The mean HSS score improved from 56.8 to 72.4 points (P < .01). Nine patients (47.4%) were rated excellent or good according to the overall subjective estimation, and 11 patients (57.9%) were satisfied with the treatment. Both HSS score and patient satisfaction were higher in patients (10 patients) who complained of intraoperative pain during synovectomy than in those (9 patients) who hardly felt the pain.

CONCLUSIONS

Localized synovial hypertrophy in the anteromedial compartment of OA knees occasionally caused symptoms of pain and catching sensations that resembled meniscal symptoms. Arthroscopic partial synovectomy was effective, especially for those who complained of intraoperative pain during synovectomy under local anesthesia.

LEVEL OF EVIDENCE

Level IV.

Mapping the rat somatosensory pathway from the anterior cruciate ligament nerve endings to the cerebrum

The anterior cruciate ligament (ACL) serves as the primary restraint to anterior tibial translation. In addition to this biomechanical function, the ACL appears to have a function in neuromuscular control. This hypothesis was formulated after the discovery of mechanoreceptors within the ACL. The full somatosensory pathway from the ACL to the cerebrum has yet to be elucidated. In order to map this sensory pathway, we conducted a viral trans-synaptic tracing experiment using the neurotropic pseudorabies virus (PRV). The pseudorabies virus was injected into the ACL of rats and allowed to replicate and spread trans-synaptically for 6-7 days. The brain and spinal cord of each sacrificed rat was then removed and processed immunohistochemically to detect the presence of PRV. PRV-immunoreactive neurons were found to be localized in several different regions from the spinal cord to the cerebrum. Four nuclei in the reticular formation of the brain stem demonstrated strong positive labeling: the mesencephalic reticular nucleus, magnocellular reticular nucleus, paragigantocellular reticular nucleus, and gigantocellular reticular nucleus. This finding suggests that the nerve endings of the rat ACL project into the cerebrum and that the reticular formation may play an important role in the afferent pathway of those nerve endings.

Distribution of substance-P nerves inside the infrapatellar fat pad and the adjacent synovial tissue: a neurohistological approach to anterior knee pain syndrome

INTRODUCTION

The purpose of the study was to determine the distribution and number of nerves inside the infrapatellar fat pad and the adjacent synovium, in particular with regards to nociceptive substance-P nerves.

MATERIALS AND METHODS

The infrapatellar fat pad of the knee was resected from 21 patients (4 male, 17 female, mean age 69 years) during the course of standard total knee arthroplasty operations performed in our clinic. The fat pad was dissected into five standardized segments, fixed in formalin and embedded in paraffin. Immunohistochemical techniques using antibodies against S-100 protein and substance-P (SP) were employed to determine and specify the nerves.

RESULTS

Studying all the detectable nerves present in 50 observation fields (200-fold magnification), we found an average of 106 S-100 versus 25 SP nerves (24%) in the synovium and 27 S-100- versus 7 SP nerves (26%) in the interior of the fat pad. The total nerve count was significantly (P < 0.001) higher in the synovium than in the fat pad for both marker types. The number of S-100 nerves was significantly (P < 0.05) higher in the central and lateral segments of the fat pad, while SP nerves were equally distributed throughout all segments of the fat-pad. SP nerves were significantly more frequently associated with blood vessels inside the fat pad (43%, P < 0.05) than in the synovial tissue (28%).

CONCLUSION

The occurrence and distribution of SP nerves inside the infrapatellar fat pad suggest a nociceptive function and a neurohistological role in anterior knee pain syndrome. The data support the hypothesis that a neurogenous infection of the infrapatellar fat pad could contribute to anterior knee pain syndrome.

The innervation of patella: anatomical and clinical study

As much interest has been focused on afferent innervation of knee than that of patella, there are few articles about patellar innervation. But in clinical practice anterior knee pain due to patellar disorders is a quite frequent problem. Our aim was to review the innervation pattern of patella and to give the topographic anatomy of the nerves. We dissected 30 knees of 15 formaldehyde-fixed cadavers. Two nerves from vastus medialis and lateralis were found to reach patellar edge. Apart from these, we were unable to find any other neural structures around patellae. Mean distances between the tuberosity of the tibia and medial and lateral nerve entry points were 90.1(range 74-102) and 96.3 mm (range 76-109), respectively. The angles between lines which join the entry points of nerves and vertical line to the center point of patella were measured in frontal plane. It was approximately 60 degrees medially and 40 degrees laterally. To confirm that these nerves are patellar pain afferents, we performed a local anesthesia test in 32 knees of 20 patients with patellofemoral pain. Clinically, there was a significant difference between the visual analogue scale (VAS) scores before and after local anesthetic injections (p<0.01). Previous studies have emphasized especially the medial innervation. We found that both superomedial and superolateral nerves were important for patellar innervation. We described precisely the entry points of these nerves to patella for selective denervation.

Patellofemorales Schmerzsyndrom

The patellofemoral pain syndrome is of high socioeconomic relevance as it most frequently occurs in young working patients. As its etiology is often unknown there is no standard treatment protocol. Several studies analyzed the different causes of patellofemoral pain and their different therapies. Static problems (pes planovalgus, instabilities, leg length differences) or chronic overuse of the knee extensor mechanism have to be identified and treated. After exclusion of intra-articular pathologies, the treatment of patellofemoral pain syndrome begins with conservative management. Stretching of the flexor and extensor muscles and training of the quadriceps muscle are the main approaches. If conservative treatment fails and patellofemoral pain persists, there are several surgical procedures for realignment of the patella in the trochlear groove and reduction of the patellofemoral pressure. Overweight patients exhibit chronic mechanical overuse of the patellofemoral joint. This leads to a higher rate of cartilage degeneration and problems at the inserting tendons and stabilizing tissues.

Efficacy of isokinetic exercise on joint position sense and muscle strength in patellofemoral pain syndrome

OBJECTIVE

The objective of this study was to demonstrate the impairment of knee joint position sense in individuals with patellofemoral pain syndrome and investigate the effects of isokinetic exercise on knee joint position sense and muscle strength.

DESIGN

A total of 24 male patients complaining of anterior knee pain caused by overexertion and 24 male healthy individuals without symptoms were included for this investigation. Isokinetic exercise protocol was carried out at angular velocities of 60 degrees/sec and 180 degrees/sec. These sessions were repeated three times per week and lasted for 6 wks. At the beginning and after 6 wks of knee passive joint position sense, quadriceps and hamstring muscle strength and pain assessments were performed.

RESULTS

After the isokinetic exercise, flexion peak torque (P < 0.05), extension peak torque (P < 0.01), flexion total work (P < 0.001), extension total work (P < 0.001), passive reproduction of knee joint position sense for 40 degrees of flexion (P < 0.05) and 50 degrees of extension (P < 0.01), and pain score (P < 0.001) improved significantly in the patellofemoral pain syndrome group.

CONCLUSION

Isokinetic exercises have positive effects on passive position sense of knee joints, increasing the muscular strength and work capacity. These findings show that using the present isokinetic exercise in rehabilitation protocols of patients with patellofemoral pain syndrome not only improves the knee joint stabilization but also the proprioceptive acuity.

Patellofemoral pain syndrome: evaluation and treatment

Patellofemoral pain syndrome is common among athletes and non-athletes. It results from an imbalance of forces acting on the patellofemoral joint, which leads to increased strain on the peripatellar soft tissues, increased patellofemoral joint stress, or both. The most important risk factors are overuse, quadriceps weakness, and soft-tissue tightness. In most cases, the etiology is multifactorial. A careful history and targeted physical examination will confirm the diagnosis and determine the most appropriate treatment. A physical therapy program that employs quadriceps strengthening, manual stretching of the lateral patellar soft-tissue structures, patellar taping, and biofeedback is successful in the majority of cases. Surgery maybe required for the few patients who do not respond to nonoperative management.

Diagnostic accuracy of a new clinical test (the Thessaly test) for early detection of meniscal tears

BACKGROUND

Clinical tests used for the detection of meniscal tears in the knee do not present acceptable diagnostic sensitivity and specificity values. Diagnostic accuracy is improved by arthroscopic evaluation or magnetic resonance imaging studies. The objective of this study was to evaluate the diagnostic accuracy of a new dynamic clinical examination test for the detection of meniscal tears.

METHODS

Two hundred and thirteen symptomatic patients with knee injuries who were examined clinically, had magnetic resonance imaging studies performed, and underwent arthroscopic surgery and 197 asymptomatic volunteers who were examined clinically and had magnetic resonance imaging studies done of their normal knees were included in this study. For clinical examination, the medial and lateral joint-line tenderness test, the McMurray test, the Apley compression and distraction test, the Thessaly test at 5 degrees of knee flexion, and the Thessaly test at 20 degrees of knee flexion were used. For all clinical tests, the sensitivity, specificity, false-positive, false-negative, and diagnostic accuracy rates were calculated and compared with the arthroscopic and magnetic resonance imaging data for the test subjects and the magnetic resonance imaging data for the control population.

RESULTS

The Thessaly test at 20 degrees of knee flexion had a high diagnostic accuracy rate of 94% in the detection of tears of the medial meniscus and 96% in the detection of tears of the lateral meniscus, and it had a low rate of false-positive and false-negative recordings. Other traditional clinical examination tests, with the exception of joint-line tenderness, which presented a diagnostic accuracy rate of 89% in the detection of lateral meniscal tears, showed inferior rates.

CONCLUSIONS

The Thessaly test at 20 degrees of knee flexion can be used effectively as a first-line clinical screening test for meniscal tears, reducing the need for and the cost of modern magnetic resonance imaging methods.

Proprioceptive recovery of patients with cervical myelopathy after surgical decompression

STUDY DESIGN

A prospective observational study.

OBJECTIVES

To determine whether proprioceptive deficit recovers after surgery and whether proprioceptive evaluation can predict functional outcome in cervical myelopathy patients.

SUMMARY OF BACKGROUND DATA

Proprioceptive sensation plays an important role in smooth, coordinated movement of the limbs. Information about proprioception ascends through the dorsal columns in the spinal cord. In severe compressive myelopathy, proprioceptive ability would be reduced and could be improved after surgical decompression. However, there have been few studies concerning proprioceptive impairment in cervical myelopathy.

MATERIALS AND METHODS

The study group included 26 cervical myelopathy patients who underwent posterior surgical decompression. Knee proprioception was assessed by joint position sense, which was evaluated by measuring the error angle when the subjects tried to reproduce the predetermined angle by extension and by flexion. Proprioceptive deficit in the study group was evaluated, compared with age-matched normal subjects. Postoperative recovery and correlation to functional status was analyzed in the study group. The Japanese Orthopedic Association (JOA) scores were used for functional evaluation.

RESULTS

The error angles were significantly higher in the study group than those in the control group before surgery. All patients in the study group finally had improvement of the error angles by a year after surgery. The average of error angles in the study group was improved 2 weeks after surgery; however, no changes were observed later. There was significant correlation between the improvement rate of the error angles 2 weeks after surgery and that of the JOA scores 2 years after surgery. There were 9 patients who had worsened proprioception 2 weeks after surgery either by extension or by flexion, all of whom had poor functional outcome.

CONCLUSIONS

Knee proprioception was impaired in cervical myelopathy and recovered after surgical posterior decompression. Proprioceptive improvement at 2 weeks correlates with the degree of improvement in JOA scores at 2 years after surgery.

The infrapatellar fat pad: anatomy and clinical correlations

This study examined the anatomy of the infrapatellar fat pad (IFP) in relation to knee pathology and surgical approaches. Eight embalmed knees were dissected via semicircular parapatellar incisions and each IFP was examined. Their volume, shape and constituent features were recorded. They were found in all knees and were constant in shape, consisting of a central body with medial and lateral extensions. The ligamentum mucosum was found inferior to the central body in all eight knees, while a fat tag was located superior to the central body in seven cases. Two clefts were consistently found on the posterior aspect of the IFP, a horizontal cleft below the ligamentum mucosum in six knees and a vertical cleft above, in seven cases. Our study found that the IFP is a constant structure in the knee joint, which may play a number of roles in knee joint function and pathology. Its significance in knee surgery is discussed.

Neuromuscular Reflexes Contribute to Knee Stiffness During Valgus Loading

We have previously shown that abduction angular perturbations applied to the knee consistently elicit reflex responses in knee joint musculature. Although a stabilizing role for such reflexes is widely proposed, there are as of yet no studies quantifying the contribution of these reflex responses to joint stiffness. In this study, we estimate the mechanical contributions of muscle contractions elicited by mechanical excitation of periarticular tissue receptors to medial-lateral knee joint stiffness. We hypothesize that these reflex muscle contractions will significantly increase knee joint stiffness in the adduction/abduction direction and enhance the overall stability of the knee. To assess medial-lateral joint stiffness, we applied an abducting positional deflection to the fully extended knee using a servomotor and recorded the torque response using a six degree-of-freedom load-cell. EMG activity was also recorded in both relaxed and preactivated quadriceps and hamstrings muscles with surface electrodes. A simple, linear, second-order, delayed model was used to describe the knee joint dynamics in the medial/lateral direction. Our data indicate that excitation of reflexes from periarticular tissue afferents results in a significant increase of the joint’s adduction-abduction stiffness. Similar to muscle stretch reflex action, which is modulated with background activation, these reflexes also show dependence on muscle activation. The potential significance of this reflex stiffness during functional tasks was also discussed. We conclude that reflex activation of knee muscles is sufficient to enhance joint stabilization in the adduction/abduction direction, where knee medial-lateral loading arises frequently during many activities.

Impaired joint proprioception in patients with cervical myelopathy

STUDY DESIGN

Prospective clinical study.

OBJECTIVES

To evaluate impairment of proprioception quantitatively in patients with cervical myelopathy.

SUMMARY OF BACKGROUND DATA

Sensory information regarding proprioception ascends through the posterior columns in the spinal cord. Damage to these columns causes proprioceptive loss in patients with spondylotic myelopathy. Nevertheless, there have been few studies regarding proprioception in patients with myelopathy.

METHODS

The authors evaluated knee proprioception in 54 cervical myelopathy patients and compared results with those of 54 age-matched healthy volunteers. Knee proprioception was assessed by joint position sense, represented by the error angles when patients reproduced predetermined angles of knee flexion.

RESULTS

The average absolute angle error of right and left knee with the predetermined position of 30 degrees of knee flexion was 2.5 +/- 1.8 (mean +/- standard deviation) and 1.8 +/- 1.2 degrees and with the predetermined 60 degrees of flexion, 4.7 +/- 2.8 and 2.8 +/- 1.4 degrees in the myelopathy and control groups, respectively. The average absolute angular errors in the myelopathy group were significantly higher than those in the control group for each predetermined knee position (P < 0.01).

CONCLUSIONS

Proprioceptive ability is impaired in patients with cervical myelopathy. Position sense can be assessed by measuring the angular error when reproducing criterion positions, and the results may reflect the severity of cervical myelopathy. Thus, the present method of measuring proprioception is easy to perform and useful for quantitative assessment of the severity of cervical myelopathy.

Amelioration of symptoms by enhancement of proprioception in patients with joint hypermobility syndrome

OBJECTIVE

Joint hypermobility syndrome (JHS) is characterized by an association between joint hypermobility and musculoskeletal pains, the latter occurring in the absence of any objective indicator of rheumatic disease. The lack of a recognizable disease marker makes this condition difficult to identify and manage. We previously observed that patients with JHS have impaired proprioception compared with that of a matched control group. The purpose of this study was to investigate whether a home-based exercise program could produce objective enhancement of proprioception as well as alleviate symptoms in JHS.

METHODS

A threshold detection paradigm was used to assess knee joint proprioception, balance was assessed using a balance board, and quadriceps and hamstring strength were measured by an isokinetic dynamometer. A visual analog scale was used to assess musculoskeletal pain, and quality of life was evaluated by a Short Form 36 questionnaire. Assessments were performed before and after an 8-week program of progressive closed kinetic chain exercises.

RESULTS

Following the exercise program, proprioceptive acuity increased in 16 of 18 subjects and was very significantly improved overall (P < 0.001). There was a comparable improvement in performance on the balance board (P < 0.001), and quadriceps and hamstring strength also increased significantly. Symptomatic improvement also occurred, in terms of both pain (P = 0.003) and quality-of-life (P = 0.029 for physical functioning; P = 0.008 for mental health) scores.

CONCLUSION

Appropriate exercises lead not only to symptomatic improvement, but also to demonstrable enhancement of objective parameters such as proprioception.

Distribution of substance-P nerve fibers in intact and ruptured human anterior cruciate ligament: a semi-quantitative immunohistochemical assessment

Numerous studies have reported qualitative and quantitative analysis of nerve supply in the anterior cruciate ligament; however, as yet relatively little is known about the distribution of substance-P nerve endings in the human anterior cruciate ligament. The objective of this work was to evaluate the distribution of substance-P nerve fibers in intact human anterior cruciate ligament, and determine if rupture of the ligament has any influence on occurrence of these receptors. The intact anterior cruciate ligament group (group 1) of osteoarthritis knee, undergoing total knee arthroplasty, consisted of nine patients (eight females) with a mean age of 65.3 years at surgery. The anterior cruciate ligament rupture group (group 2) consisted of 20 patients (18 males and 2 females) with a mean age of 27.8 years at reconstruction. Healing time of the torn ligament in vivo, determined by the time period between the rupture and reconstruction, lasted from 1 to 40 months and the patients were divided into 3 groups (I, II and III) embracing diverse time periods. All harvested anterior cruciate ligaments were sectioned in thirds so that there was a proximal, middle and distal third for each ligament. The distribution of nociceptive receptors was studied by immunohistochemistry with monoclonal antibody to substance-P, including the semi-quantitative assessment. No significant difference was found between the number of substance-P nerve fibers in the proximal, middle and distal third of the intact anterior cruciate ligament (p>0.05). During the first 4 months after injury (group I) the mean number of neuropeptide-containing fibers was greater in the proximal than in the distal third (p=0.048996). The number of SP-positive nerve fibers in the proximal third decreased between 5 and 12 months after rupture, in a statistically significant manner (p=0.045864). This study showed that distribution of the nociceptive nerve supply, positively stained for substance-P, is equal among the intact anterior cruciate ligament. The substance-P nerve ending density was significantly affected by the injury as well as by the time since rupture. The results of this study provide immunohistochemical evidence suggesting that between 1 to 4 months after rupture the site of the injury undergoes neurogenic inflammation, which could have an influence on the healing course of the torn ligament.

Proprioception and performance after anterior cruciate ligament rupture

The aim of this study was to investigate the characteristics of proprioception in patients with an anaterior-cruciate-ligament (ACL)-injured knee and to determine whether there is a correlation between proprioception and performance. We studied 32 patients with unilateral isolated ACL ruptures. Proprioception of the knee was evaluated by examining the joint position sense. Functional performance was evaluated with the one-leg hop (OLH) and one-leg vertical jump (OLV) tests. The mean error angle of the joint position sense was 3.6+/-1.5 degrees on the intact side and 5.2+/-1.9 degrees on the injured side. The joint position sense was thus clearly reduced on the injured side (p<0.05). The distance of jumping in the OLH test and the height of jumping in the OLV test was also clearly reduced on the injured side compared with that on the intact side (p<0.01) both with and without visual control. Moreover, we found a significant correlation between proprioception and performance in the ACL-injured knees, and this correlation was more distinct with visual deprivation. In conclusion, decreased proprioception in patients with ACL deficiency reduced their functional ability.

Analyses of dynamic co-contraction level in individuals with anterior cruciate ligament injury

BACKGROUND

A complete understanding of neural mechanisms by which ligament receptors may contribute to joint stability is not well established. It has been suggested that these receptors may be involved in a neuromuscular process related to the modulation of dynamic co-contraction, as a means of guaranteeing functional joint stability.

HYPOTHESIS

Individuals with ACL injury have diminished dynamic co-contraction.

STUDY DESIGN

Exploratory, cross-sectional design.

METHODS

Ten subjects with unilateral ACL injury treated conservatively, and ten subjects without history of injury participated in the study. The co-contraction level was assessed through EMG recordings of the vastus lateralis and biceps femoris before and after a perturbation imposed on the subjects during a walking task.

RESULTS

Subjects with ACL injury presented significantly lower co-contraction level pre-perturbation (p = 0.045) and post-perturbation (p = 0.046) than those in the control group.

CONCLUSIONS

The bilateral decrease in muscular co-contraction presented by individuals with ACL injury suggests that ligament and joint receptors may be responsible for a bilateral dynamic increase in muscle and joint stiffness that could result in a greater joint stability.

CLINICAL RELEVANCE

This study analyzed a neuromuscular mechanism that might contribute to the functional stability of the knee joint.

The effect of local and general fatigue on knee proprioception

PURPOSE

The purpose of this study was to compare the effects of local and general fatigue loads on knee proprioception.

TYPE OF STUDY

Experimental controlled study.

METHODS

Proprioception of the knee joint was evaluated by measuring absolute angular error (AAE) at matching defined index angles before and after 2 different types of fatigue protocols (local load and general load) in 27 healthy male volunteers. Local load was provided with maximum isokinetic knee flexion-extension on the isokinetic dynamometer, and general load was 5 minutes running on a treadmill.

RESULTS

After local load, a significant decrease in peak torque of knee flexors and extensors was found, but no significant change in AAE was seen. In contrast, after general load, a significant increase of AAE was noted without significant muscle weakness.

CONCLUSIONS

The different results in previous studies evaluating the effect of fatigue on knee proprioception may have been affected by the difference of fatigue protocols, whether local or general load. Although local load was intended to produce local fatigue of the knee, which may cause dysfunction of muscle mechanoreceptors, general load may have produced general fatigue and affected other mechanisms in the proprioceptional pathway. The results of the present study suggest that decreased reproduction ability after general load is not due to the loss of peripheral afferent signals, but to other factors, especially deficiency of central processing of proprioceptive signals.

CLINICAL RELEVANCE

To prevent knee injury caused by fatigue-induced proprioceptional decline, muscle endurance training alone is not enough, and neuromuscular training, including central motor programming, is essential.

Proprioception of the shoulder joint after surgical repair for Instability: a long-term follow-up study

BACKGROUND

Proprioceptive capabilities play an important role in stability of the shoulder joint.

HYPOTHESIS

Decreased proprioceptive capabilities can improve by surgical repair of shoulder instability.

STUDY DESIGN

Prospective long-term study.

METHODS

The proprioceptive capabilities of 14 patients with recurrent anterior shoulder instability were examined preoperative and with a minimum follow-up of 5 years postoperative using the angle reproduction test. The patients' data were compared to a healthy control group.

RESULTS

The joint position sense improved significantly in abduction, flexion, and rotation (P <.05). The preoperative difference from the target joint position was 9.3 degrees (SD, 4.6 degrees ) for the summarized positions in abduction, 9.1 degrees (SD, 4.5 degrees ) in flexion, and 10.1 degrees (SD, 5.1 degrees ) in rotation. Postoperatively, it improved to 5.6 degrees (SD, 2.9 degrees ) in abduction, 5.6 degrees (SD, 2.7 degrees ) in flexion, and 5.0 degrees (SD, 1.8 degrees ) in rotation. The joint position sense of the uninvolved contralateral shoulder improved too.

CONCLUSIONS

Five years after surgical repair for shoulder instability, the joint position sense improved significantly, to a level of normal, healthy shoulders.

Effects of anterior lumbar spinal fusion on the distribution of nerve endings and mechanoreceptors in the rabbit facet joint: quantitative histological analysis

The purpose of this study was to investigate the density and distribution of neural endings in rabbit lumbar facet joints after anterior spinal fusion and to evaluate the effects of intervertebral immobilization. An extraperitoneal approach was applied, and L5/6 was fixed with a plate and screws. Bilateral L4/5, L5/6, and L6/7 facet joint capsules were harvested from the rabbits 4, 8, and 16 weeks postoperatively. Capsular tissues were processed using a modified gold chloride staining method, and the specimens were sliced into 15-micro m sections. All sections were analyzed microscopically, and neural ending numbers per unit volume were calculated. Three types of neural ending were identified in each specimen: Pacinian corpuscles, Ruffini corpuscles, and free nerve endings. In the L5/6 fusion segment there was a significant decrease in the number of Pacinian corpuscles at 4 weeks and of Ruffini corpuscles at 4, 8, and 16 weeks after the fusion compared with the control; and in the L4/5 upper adjacent segment there was a significant increase in the number of free nerve endings. The number of Ruffini endings for the L6/7 lower adjacent segment was significantly lower more than 8 weeks after the fusion. These results suggest that immobilization of the intervertebral segment causes a reduction in the number of mechanoreceptors in the facet joint capsules because of the reduction in mechanical stimulation. Moreover, in the upper adjacent facet joint there may be neural sprouting caused by nociceptive stimulation.

Idiopathic anterior knee pain in adolescents

Anterior knee pain is a common problem and its management can be challenging. A thorough evaluation of the patient's history and examination of the lower extremity and knee extensor mechanism is necessary. Clinically elusive conditions should be considered before ascribing the pain as idiopathic, the most common diagnosis of adolescent anterior knee pain. In the majority of cases, the natural history of idiopathic anterior knee pain is improvement and resolution. Nonoperative therapeutic measures usually provide improved knee function.

Effect of peripheral afferent alteration of the lateral ankle ligaments on dynamic stability

BACKGROUND

The sensorimotor influence of the lateral ankle ligaments in muscle activation is unclear.

HYPOTHESIS

The lateral ankle ligaments have significant sensorimotor influence on muscle activation.

STUDY DESIGN

Controlled laboratory study.

METHODS

Muscle-firing characteristics in response to a high-speed inversion perturbation and during gait were assessed in 13 normal subjects. Solutions (1.5% lidocaine or a placebo of saline) were injected bilaterally into the anterior talofibular and calcaneofibular ligaments (1.5 ml per ligament) to alter peripheral afferent influence. Subjects were again tested with the same protocol.

RESULTS

The protective response of the anterior tibialis and peroneal muscles during inversion perturbation and mean muscle activation amplitude decreased during running after both injections. After injection, no significant differences were seen for muscle reflex latencies, maximum amplitude, time to maximum amplitude during inversion perturbation, or mean amplitude during walking.

CONCLUSION

The lateral ankle ligaments have a sensorimotor influence on muscle activation.

CLINICAL RELEVANCE

Induced edema from the injected solutions may have altered the sensorimotor influence of the lateral ankle ligaments, thereby inhibiting the dynamic ankle stabilizers. This finding suggests that dynamic stability may be compromised because of swelling after joint injury.

Innervation and functional characteristics of connective tissues, especially elastic fibers, in human fetal thoracic intervertebral articular capsule and its surroundings

The articular capsules between the thoracic vertebrae, which have physiologically different functions from those of other levels of the vertebrae, have yet to be subjected to neuro-anatomical and fine structural analysis. In the present study, we analyzed serial frozen sections of decalcified thoracic vertebrae in human fetuses, and identified the articular capsule tissue with its unique distribution of elastic fibers. The fine structure of the elastic fibers was studied by transmission electron microscopy. In the early-stage fetus, the fibrous membrane forming the lateral intervertebral articular capsule contained abundant thin elastic fibers consisting of microfibrils. In the late-stage fetus, the lateral capsule of fibrous membrane was occupied by thick elastic fibers. A medial articular capsule, namely the ligamenta flava, contained numerous thick elastic fibers in both early and late-stage fetuses. The distributional differences in nerve fibers between early and late-stage fetuses were determined by immunostaining, using antibodies raised against protein gene product 9.5 (PGP 9.5; ubiquitin carboxyl-terminal hydrolase). Innervation by PGP 9.5 immunoreactive fibers was limited to the areas of the articular capsules near the blood vessels, which may indicate their functional relation with blood flow. No PGP 9.5 immunoreactive fibers were found in the ligamenta flava of the late-stage fetus. Innervation might be directly involved in the development of the intervertebral articular capsules in normal human fetuses.

Biochemical change in joint fluid after isometric quadriceps exercise for patients with osteoarthritis of the knee

OBJECTIVE

The purpose of this study was to analyze the biochemical changes in the joint fluid, and pain relief resulting from isometric quadriceps exercise in patients with osteoarthritis of the knee.

DESIGN

Nineteen osteoarthritic knees in 17 patients with joint effusion were included. The patients performed isometric quadriceps exercise for 3 months. Isometric muscle torque at 30 and 60 degrees flexion, pain as measured using the visual analog scale and biochemical markers in joint fluid were evaluated before and after the exercise.

RESULTS

Pain score decreased from 3.9 to 2.3 after 12 weeks of exercise (P<0.001). Extension torque at 30 and 60 degrees knee flexion significantly increased from 4.7 to 6.9 kgm (47% increase, P<0.001) and from 10.8 to 12.6 kgm (17% increase, P<0.005) after 12 weeks of exercise. The molecular weight of hyaluronan increased from 2.11 to 2.40x10(6)(P<0.05) and the viscosity of joint fluid increased from 45.8 to 59.8 mPas after 12 weeks of exercise (P<0.05). Chondroitin 4-, 6-sulfate concentration in joint fluid decreased from 81.9 to 75.5 nmol/ml (P<0.05).

CONCLUSIONS

Isometric quadriceps exercise resulted in significant changes in joint fluid biochemical parameters, and these changes, at least in part, may explain the ameliorative effect of muscle exercise for osteoarthritis of the knee.

The effects of proprioceptive or strength training on the neuromuscular function of the ACL reconstructed knee: a randomized clinical trial

OBJECTIVES

The purpose of this study was to determine the effects of a proprioceptive training program (PT) vs. a strength training (ST) program on neuromuscular function after anterior cruciate ligament (ACL) reconstruction. The second purpose was to establish the determinants of functional ability for the operated limb.

METHODS

Ten participants with unilateral ACL reconstructions were randomly assigned to one of the following 12-week training protocols: (1) isotonic ST, and (2) PT. The outcome measures were: (1) peak torque time of the hamstring muscles (PeakTT), (2) average concentric and eccentric torques of the quadriceps and hamstring muscles, (3) one-legged single hop for distance (SLHD), (4) one-legged time hop (TH), and (5) subjective scores.

RESULTS

: There was a significant group by time interaction effect for PeakTT (P = 0.017). The PT group demonstrated greater percent change in isokinetic torques than the ST group at the end of the 12 weeks (P < or = 0.05). Participants in both groups demonstrated similar significant gains in functional ability and subjective scores (P < or = 0.014). Quadriceps strength is a determinant of functional ability for the operated limb (R2 = 0.72).

CONCLUSIONS

: Both training protocols influenced PeakTT. The beneficial effects of ST on PeakTT appear to be load-dependent, while sufficient practice may be crucial in maintaining PeakTT improvements induced by PT. Proprioceptive training alone can induce isokinetic strength gains. Restoring and increasing quadriceps strength is essential to maximize functional ability of the operated knee joint.

Reflex muscle contractions can be elicited by valgus positional perturbations of the human knee

Experimental evidence on the reflex responses of thigh muscles to valgus mechanical perturbations at the human knee are presented. Random step positional deflections, ranging from 5 degrees to 12 degrees at 60 degrees /s, were applied to the fully extended knees of seven healthy subjects. Subjects were instructed to maintain a constant background co-activation ( approximately 2-11% MVC) of the quadriceps and hamstring muscles prior to and during the mechanical stimulus. We found that the reflex response to sustained valgus joint deflection in the vasti muscles had longer onset latencies (range: 83-92ms) than did the stretch reflex in the same muscles (latencies: 29-31ms). This reflex EMG response consisted typically of a peak followed by sustained muscle activity throughout the step perturbation. The sustained EMG activity was dependent on the amplitude of the perturbing stimulus, but in a nonlinear manner. The long latency of the valgus response suggests that the reflex originates in nonmuscular sensory pathways, potentially from mechanoreceptors lying in periarticular tissues such as joint ligaments and capsule. Analysis of the spatial distribution of reflex responses showed an asymmetrical pattern with preferential activation of medial vs. lateral muscles of the knee. We assess whether these asymmetric reflex contractions could promote joint stability, either by inducing generalized joint stiffening, or by preferential activation of those muscles that are best suited to resist induced ligament strain.

Strategies for enhancing proprioception and neuromuscular control of the knee

Proprioception and neuromuscular control of the knee are compromised after ligament injury and must be regained if the athlete is to return to high level sports at a normal injury risk level. The anterior cruciate ligament deficient and reconstructed knee will be used as a model to describe differences in proprioception and neuromuscular control to those of an uninjured knee. The purpose of the current review is threefold. First, the basic science of proprioception and neuromuscular control specific to the knee will be summarized and reviewed. The review will include an overview of terminology, neurophysiology, and the effects of injury on the function of both lower limbs. Second, tools used for assessment and rehabilitation of proprioceptive deficits will be evaluated. Specific rehabilitation procedures that incorporate prophylactic conditioning that focus on transitioning the injured athlete back into sport will be presented. Finally, the literature with respect to gender variation in proprioception and neuromuscular control will be evaluated. The goal of the current review is to provide the clinician and the clinical scientist with sufficient background information for the development of quantitative methods to evaluate a patient's functional capacity and to assist in preventative, preoperative, and postoperative decision-making strategies.

Changes in weight-bearing following injury or surgical reconstruction of the ACL: relationship to quadriceps strength and function

PURPOSE

Changes in weight-bearing an average of 1.5 months after ACL injury (ACLD) and up to 3 months after surgical reconstruction (ACLR) were investigated using a force platform. Correlations between force platform test variables, quadriceps strength and functional self-report scores were also examined.

RESULTS

Each force platform test revealed impaired weight-bearing by either ACLD and/or ACLR subjects. Many variables were correlated to quadriceps strength; therefore, improved strength in ACLR subjects by 6 weeks post-operative negated any weight-bearing impairment. No single force platform variable correlated with the subjects' perception of function.

CONCLUSION

Only the step up/over test provided insight into disability in these patients. Modification of force platform analysis programs may allow for other clinical questions to be answered.

Characteristics of Shoulder-Position Sense: Effects of Mode of Movement, Scapular Support, and Arm Orientation

Context:

Although the repositioning test is widely used to evaluate proprioception, the effects of several test-associated variables on the test outcome are not known.

Objective:

To determine the effects of mode of movement, scapular support, and arm orientation on shoulder-position sense.

Participants:

49 healthy, randomly selected men.

Methods:

The repositioning test was conducted in 4 settings in which mode of movement, scapular support, and arm orientation were manipulated differently.

Main Outcome Measure:

Position-sense acuity was quantified as repositioning accuracy and consistency.

Results:

Active limb movement significantly enhanced repositioning accuracy and consistency compared with passive movement. Repositioning consistency was significantly better when the scapula was supported than when it was not. Arm orientation had no significant effect on repositioning accuracy and consistency.

Conclusion:

The protocol for evaluating or rehabilitating shoulder proprioception should include active limb movement with the scapula unsupported to ensure that it refects a patient’s proprioceptive demand during functional activities.

Sources of anterior knee pain

The anterior part of the knee consists mainly of structures belonging to the patellofemoral joint, which includes a variety of tissues, such as cartilage, subchondral bone, synovial plicae, infrapatellar fat pad, retinacula, capsule, and tendons. Each of these structures, alone or in combination, can be a source of anterior knee pain. Unphysiologic load or changed metabolic activities can lead to structural failure with loss of homeostatic conditions.

Mechanoreceptors in the anterior cruciate ligament contribute to the joint position sense

We have investigated the correlation between the number of mechanoreceptors in anterior cruciate ligament (ACL) remnants and the joint position sense just before an ACL reconstruction in 29 patients. The number of mechanoreceptors was evaluated histologically, using the Gairns gold chloride method. Mechanoreceptors were also found in patients who had a long interval between injury and the operation. A joint position sense test was done within 3 days before surgery. We found a positive correlation between the number of mechanoreceptors and accuracy of the joint position sense, suggesting that proprioceptive function of the ACL is related to the number of mechanoreceptors. Therefore, we should consider preserving ACL remnants during ACL reconstruction.

Muscle torques in total knee arthroplasty with subvastus and parapatellar approaches

The current study was designed to compare muscle torques when using the subvastus and parapatellar approaches for unilateral total knee arthroplasty. Twelve female patients had unilateral total knee arthroplasty with the subvastus approach from January 1997 to June 1998. The historic control group consisted of 16 female patients who had unilateral total knee arthroplasty with the parapatellar approach from July 1994 to January 1997. Six and 12 months after surgery, a Cybex dynamometer was used to measure isometric and isokinetic muscle strength. Two parameters were used to compare the two approaches, the first parameter was the difference in peak torque between the surgically treated knee and the baseline value for the healthy knee, and the second parameter was the hamstring to quadriceps peak-torque ratio, again using the value for the healthy knee as baseline. The subvastus approach resulted in an initial higher peak torque in the quadriceps 6 months after surgery, but this difference became insignificant 12 months postoperative. Using the subvastus approach, the hamstring to quadriceps peak-torque ratio reached the normal range (0.50-0.80) sooner than was the case using the parapatellar approach. There is a phenomenon of cross adaptation of the untreated knee to the surgically treated knee, and knees operated on by the subvastus approach showed functional recovery at an earlier date than those operated on by the parapatellar approach.

The Effect of a Simulated Knee Effusion on Lower Extremity Performance

Context:

Researchers have suggested that quadriceps inhibition resulting from a simulated knee effusion would lead to decreased lower extremity performance.

Purpose:

To investigate the relationship between a simulated knee effusion and lower extremity performance.

Participants:

9 college students.

Methods:

Subjects performed 3 functional-performance tests before and after a simulated knee effusion. Measurement was the average distance hopped for a single hop and crossover hop for distance and time for completion on a timed hop test.

Results:

An analysis of variance revealed significant change in average test scores after injection only for the timed hop in subjects receiving a 60-ml injection.

Conclusion:

Nonsignificant differences might have resulted from compensation from other muscle groups, fluid movement within the knee joint, and absence of an inflammatory process. Further research on the relationship between simulated knee effusion and lower extremity performance is needed.

Proprioception of the ankle: a comparison between female teenaged gymnasts and controls

Proprioceptive mechanisms appear to play a role in stabilizing the joints and may serve as a means for interplay between static stabilizers and dynamic muscular restraints. The purpose of our study was to investigate whether or not gymnastic training has any effect on the balance and on proprioception in an ankle, as seen in gymnasts and in nongymnasts. We evaluated the proprioceptive ability of the ankle using four different tests (a one-leg-standing test, a single-limb-hopping test, an active angle-reproduction test, and a passive angle-reproduction test). Proprioception of the ankle was measured in 40 subjects who were assigned to two experimental groups. Group 1 (n: 20) were healthy control subjects, and group 2 (n: 20) were teenaged female gymnasts. The sense of position of a joint was actively measured using a Cybex NORMTM isokinetic dynamometer and measured passively with a proprioception-testing device. A Mann-Whitney U test was used to compare mean values of the gymnasts to the controls. Results revealed statistically significant differences (p<0.05) between two groups. We found no statistically significant differences between the dominant and nondominant ankle in volunteers or in gymnasts, in all tests. The results of this study suggest that gymnastic training has a positive influence on sense of position of the ankle joint and on balance, in addition to increasing muscle tone.

The effect of bracing on proprioception of knees with anterior cruciate ligament injury

This paper is a comprehensive review on the effect of bandaging, bracing, and neoprene sleeves on knee proprioception following anterior cruciate ligament (ACL) injury and reconstruction with a focus on studies that have measured joint position sense and threshold to detection of passive knee motion. Disruption of the ACL does not appear to alter joint position sense soon after injury, although there is evidence that in some subjects deterioration may occur over time. An ACL tear creates a deficit in the threshold to detection of passive knee motion soon after injury and in those with chronic tears. The magnitude of worsening is less then 1.0 degree of movement in flexion-extension and of questionable concern from a clinical and functional perspective. Application of a functional brace or neoprene sleeve to the ACL-deficient limb does not improve the threshold to detection of passive knee motion; however, application of an elastic bandage to a knee with an ACL tear improves joint position sense. Reconstruction of a torn ACL is associated with a deficit in the threshold to detection of passive knee motion, and during the first year of healing the use of a neoprene sleeve provides improvement. Two years following ACL reconstruction there is no deficit in the threshold to detection of passive knee motion and the use of a brace has no effect on this outcome.

Clinical assessment and rehabilitation of shoulder and knee sensorimotor control

The orthopedic surgeon must perform a thorough evaluation of an unstable joint to derive the accurate diagnosis. One component of this examination is evaluation of the sensorimotor system. This article provides an overview of techniques and methodology used to assess the sensorimotor system. Rehabilitation concepts are presented to assist the physician during patient consultation following injury or surgery.

Donor-site morbidity and anterior knee problems after anterior cruciate ligament reconstruction using autografts

The authors review the current knowledge on donor site-related problems after using different types of autografts for anterior cruciate ligament (ACL) reconstruction and make recommendations on minimizing late donor-site problems. Postoperative donor-site morbidity and anterior knee pain following ACL surgery may result in substantial impairment for patients. The selection of graft, surgical technique, and rehabilitation program can affect the severity of pain that patients experience. The loss or disturbance of anterior sensitivity caused by intraoperative injury to the infrapatellar nerve(s) in conjunction with patellar tendon harvest is correlated with donor-site discomfort and an inability to kneel and knee-walk. The patellar tendon at the donor site has significant clinical, radiographic, and histologic abnormalities 2 years after harvest of its central third. Donor-site discomfort correlates poorly with radiographic and histologic findings after the use of patellar tendon autografts. The use of hamstring tendon autografts appears to cause less postoperative donor-site morbidity and anterior knee problems than the use of patellar tendon autografts. There also appears to be a regrowth of the hamstring tendons within 2 years of the harvesting procedure. There is little known about the effect on the donor site of harvesting fascia lata and quadriceps tendon autografts. Efforts should be made to spare the infrapatellar nerve(s) during ACL reconstruction using patellar tendon autografts. Reharvesting the patellar tendon cannot be recommended due to significant clinical, radiographic, and histologic abnormalities 2 years after harvesting its central third. It is important to regain full range of motion and strength after the use of any type of autograft to avoid future anterior knee problems. If randomized controlled trials show that the long-term laxity measurements following ACL reconstruction using hamstring tendon autografts are equal to those of patellar tendon autografts, we recommend the use of hamstring tendon autografts because there are fewer donor-site problems.

Dynamic knee stability: current theory and implications for clinicians and scientists

We will discuss the mechanisms by which dynamic knee stability may be achieved and relate this to issues that interest clinicians and scientists concerned with dynamic knee stability. Emphasis is placed on the neurophysiologic evidence and theory related to neuromuscular control. Specific topics discussed include the ensemble firing of peripheral mechanoreceptors, the potential for muscle stiffness modulation via force and length feedback, postural control synergies, motor programs, and the neural control of gait. Factors related to answering the difficult question of whether or not knee ligament injuries can be prevented during athletic activities are discussed. Prevention programs that train athletes to perform their sport skills in a safe fashion are put forth as the most promising prospect for injury prevention. Methods of assessing neuromuscular function are reviewed critically and the need for future research in this area is emphasized. We conclude with a brief review of the literature regarding neuromuscular training programs.

Spinal and supraspinal factors in human muscle fatigue

Muscle fatigue is an exercise-induced reduction in maximal voluntary muscle force. It may arise not only because of peripheral changes at the level of the muscle, but also because the central nervous system fails to drive the motoneurons adequately. Evidence for "central" fatigue and the neural mechanisms underlying it are reviewed, together with its terminology and the methods used to reveal it. Much data suggest that voluntary activation of human motoneurons and muscle fibers is suboptimal and thus maximal voluntary force is commonly less than true maximal force. Hence, maximal voluntary strength can often be below true maximal muscle force. The technique of twitch interpolation has helped to reveal the changes in drive to motoneurons during fatigue. Voluntary activation usually diminishes during maximal voluntary isometric tasks, that is central fatigue develops, and motor unit firing rates decline. Transcranial magnetic stimulation over the motor cortex during fatiguing exercise has revealed focal changes in cortical excitability and inhibitability based on electromyographic (EMG) recordings, and a decline in supraspinal "drive" based on force recordings. Some of the changes in motor cortical behavior can be dissociated from the development of this "supraspinal" fatigue. Central changes also occur at a spinal level due to the altered input from muscle spindle, tendon organ, and group III and IV muscle afferents innervating the fatiguing muscle. Some intrinsic adaptive properties of the motoneurons help to minimize fatigue. A number of other central changes occur during fatigue and affect, for example, proprioception, tremor, and postural control. Human muscle fatigue does not simply reside in the muscle.

Effect of fatigue on knee proprioception: implications for dynamic stabilization

The high incidence of injuries that occur later during a session of sports or recreational activities suggests that fatigue may contribute to altered neuromuscular control of the lower limb and an individual's subsequent altered ability to dynamically stabilize the knee joint. One possible mechanism is a fatigue-mediated alteration in proprioception. This paper reviews experimental evidence of fatigue-induced changes in knee joint position sense and movement sense, or kinesthesia. We will discuss the possible physiological mechanisms behind these changes, including the role of joint and muscle receptors in proprioception and neuromuscular control of the knee, and the role of fatigue in changes in afferent output from muscle and joint receptors. We will then explore the implications that alteration in proprioception may have for dynamic stabilization of the knee joint.

Macroscopic and histological assessments of the cruciate ligaments in arthrosis of the knee

We examined the macroscopic appearance of both cruciate ligaments in 52 knees during knee replacement. It was classsified as normal, abnormal or ruptured. The ligaments were also evaluated histologically: stage 0 (normal), stage I (degeneration of < 1/3 of the collagen fibers), stage 2 (degeneration of 1/3-2/3) and stage 3 (> 2/3). 17 anterior cruciate ligaments (ACL) were normal, 14 were abnormal and 21 ruptured. All the posterior cruciate ligaments (PCL) were normal. 14 ACL were stage 0, 6 stage 1, 8 stage 2 and 24 were stage 3. 22 PCL were stage 0, 14 stage 1, 13 stage 2 and 3 were stage 3. When the ACL was abnormal or ruptured, the PCL was stage 0 only in one fourth of the cases. The long-term results of TKR retaining the PCL should be better if the ligament is strong. The intraoperative assessment of the macroscopic appearance of the ACL reflects the histological state of the PCL.

Anterior cruciate ligament function after tibial eminence fracture in skeletally mature patients

We compared anterior cruciate ligament function in skeletally mature patients after treatment of tibial eminence fractures with that of patients in two other groups: patients who had anterior cruciate ligament deficiency and patients who had undergone anterior cruciate ligament reconstruction using bone-patellar tendon-bone autografts. The Lysholm questionnaire was used to evaluate symptoms and KT-1000 arthrometry was used to determine objective knee laxity at an average follow-up of 5.2 years. Knee joint proprioception was assessed with a new method designed to test joint position sense. The Lysholm score for the tibial eminence group was 94 +/- 7. Only the patients in the anterior cruciate ligament-deficient group demonstrated statistically significantly increased laxity and inferior proprioception when the injured leg was compared with the uninjured leg. Both laxity and proprioception were statistically inferior for the anterior cruciate ligament-deficient group when compared with both the treated tibial eminence fracture group and the anterior cruciate ligament-reconstructed group. No statistically significant difference was observed between the anterior cruciate ligament-reconstructed and treated tibial eminence fracture groups. Correlation was observed between laxity and proprioception when all patients were analyzed. The results demonstrate that appropriate treatment of tibial eminence fractures restores stability and proprioception to the knee.

Retain or sacrifice the posterior cruciate ligament in total knee arthroplasty? A histopathological study of the cruciate ligament in osteoarthritic and rheumatoid disease

BACKGROUND

The decision whether to retain or resect the posterior cruciate ligament in total knee arthroplasty is at present determined clinically by preoperative radiological variables focusing upon the amount of joint destruction, and subsequent soft tissue contractures. However, these variables give only indirect information on the histological integrity and proprioceptive properties of the posterior cruciate ligament.

METHODS

Twenty posterior cruciate ligaments, obtained during total knee arthroplasty, were evaluated histologically to study the relation between the degree of preoperative radiological joint destruction, structural integrity of the posterior cruciate ligament and the neurological integrity of the targeted tissue. Eleven patients had osteoarthritis and nine patients rheumatoid arthritis. Haematoxylin and eosin, Alcian blue (mucoid degeneration), elastica von Gieson, Gomori (elastic fibres and collagen), and immunohistochemical staining for neural structures were used.

RESULTS

In all but one of the posterior cruciate ligaments, morphologically intact neural tissue was present in the peritendineum of the ligaments. Structural integrity of the collagen framework was present in only seven posterior cruciate ligaments. These cases all had grade three or four radiological joint destruction. In 13 of the specimens a certain degree of mucoid degeneration of collagen was present. All patients with grade five radiological knee joint destruction displayed mucoid degeneration and irregularity of the posterior cruciate ligament fibres.

CONCLUSION

Because of the extensive architectural and probably functional damage of the posterior cruciate ligament in patients who have grade five radiological knee joint destruction, retention of the posterior cruciate ligament in knee prosthesis should not be advocated.

Neural anatomy of the transverse carpal ligament

Carpal tunnel syndrome is one of the most commonly diagnosed disorders of the upper extremity. The etiology of the neuropathy is known to be associated with many disorders, with the etiology of carpal tunnel syndrome mainly attributable to ischemia of the median nerve. The purpose of this study was to determine the presence of neural elements within the transverse carpal ligament. Fourteen transverse carpal ligaments were harvested from seven male and seven female fresh frozen cadavers with an average age of 76 years. The tissues were stained with S-100 using a standard immunoperoxidase technique used to localize neural tissue. The transverse carpal ligament consisted of interwoven bundles of fibrous connective tissue. It was found to have an intraligamentous and extraligamentous neural network consisting mostly of free nerve endings and pacinian corpuscles. Ruffini's corpuscles were not identified. This study showed that there is neural innervation to the transverse carpal ligament. Pacinian corpuscles have been shown to be mechanoreceptors which respond to changes in joint position, whereas free nerve endings have been identified as nociceptors. Neural innervation were present in the transverse carpal ligament, and the nociceptive information relayed by these neural elements may contribute to the pain associated with carpal tunnel syndrome. In addition to being a mechanical wrist stabilizer, the transverse carpal ligament also may play a role in proprioception of the wrist.