Nerve supply of the human knee and its functional importance

The effects of knee effusion on quadriceps strength and knee intraarticular pressure

The purpose of this study was to determine the effect of varied amounts of effusion on quadriceps strength and knee intraarticular pressure (IAP) during active knee movement. Five subjects had 60 ml of saline, in 20 ml increments, infused into the right knee. Quadriceps strength and knee IAP were continuously measured at each level of effusion, while the subject performed isokinetic knee exercises. A control group of five subjects performed the same exercises, but with no saline infusion. No significant changes in quadriceps strength were seen in the control group. In the experimental group, quadriceps strength decreased as the amount of effusion increased, and increased following aspiration. The greatest decrease in strength occurred at those knee positions where IAP was highest (full flexion and extension). Results of this study indicate that quadriceps strength is diminished and IAP markedly increased when an effused knee is exercised.

The intraoperative evaluation of the neurosensory function of the anterior cruciate ligament in humans using somatosensory evoked potentials

Most of the investigation of the properties of the anterior cruciate ligament (ACL) has focused on its biomechanical functions. There has been increasing interest in the study of the possible neuroreceptor function of the ACL and its role in providing important proprioceptive feedback. Anatomic and histologic studies in humans have shown the presence of neuroreceptors within the anterior cruciate ligament. Indirect evidence exists that proprioception is diminished in the ACL-deficient knee. However, direct evidence in humans of the actual origin of the afferent impulses from within the ACL itself is lacking. Measurement of direct electrical afferent activity, occurring on stimulation of the ACL, should provide this evidence. Somatosensory evoked potentials (SEP) measure the electric potentials evoked in the cerebral cortex upon stimulation of a peripheral neuroreceptor. Carried by the posterior columns of the spinal cord, they reflect activity of the proprioceptive fibers. During arthroscopic procedures performed on nine patients, the normal ACL was stimulated by the use of electrodes applied to the femoral end, midsubstance, and tibial end, and cortical potentials thus evoked were recorded. In all cases, SEPs were recorded at the cerebral cortex upon stimulation of the ACL. The greatest potentials were reported upon stimulation of the midsubstance of the ligament. These findings provide direct evidence for, and strongly support the presence of, active proprioceptive receptors within the intact anterior cruciate ligament of the human knee.

Calcitonin gene-related peptide, substance P and GAP-43/B-50 immunoreactivity in the normal and arthrotic knee joint of the mouse

The aim of this study was to describe the normal distribution of calcitonin gene-related peptide (CGRP) and substance P (SP) containing fibres in the knee joint of the mouse and to obtain insight into the changes in innervation associated with degenerative processes in the joint. Arthrosis was induced by a single subpatellar intra-articular injection of bacterial collagenase. After decalcification in EDTA solutions, the CGRP and SP fibres were visualized by peroxidase-antiperoxidase pre-embedding immunocytochemistry for light microscopy. Control experiments on the mouse brain as a reference for the effect of EDTA on the immunostaining showed that the decalcification procedure with EDTA had not impaired the immunostaining. A rich innervation of thin varicose CGRP and SP immunoreactive fibres was found in most peri- and intra-articular tissue components. The periosteum, synovial tissues, the joint capsule and the intra-articular fat tissues were richly innervated. Less intense innervations were also found in the subchondral bone plates of the tibio-femoral joint and of the patella. Fibres were also found in the soft tissues between the patellar tendon and the femoral groove. No differences could be found between the location of CGRP and SP fibres with respect to the localization in the joint, but generally more CGRP fibres were found. The collagenase-induced osteoarthrosis was characterized by sclerosis of the subchondral bone, patellar dislocation, osteophyte formation, synovial proliferation and by severe cartilage abrasion, particularly on the medial side of the femoro-tibial joint. The overall distribution of CGRP and SP fibres was the same as in the control joints. However, major differences were found in all studied joints at specific locations around the cruciate ligaments, in the synovium around the patella, in the soft tissues lateral of the patella and in plica tissue between the patella and femoral groove. The CGRP and SP innervation was no longer detectable by immunolabelling with the antibodies. With a polyclonal antibody to the growth associated protein GAP-43/B-50, signs of degenerated axonal profiles were observed in these locations. At other peripheral locations, such as the muscles, the GAP-43/B-50 distribution was normal. In conclusion, the present study provides detailed information on the localization of CGRP and SP fibres, which may be involved in pain perception. Knowledge of the changes that occur during arthrosis may give more insight into the clinical symptoms.

Role of arthroscopic lateral release in the treatment of patellofemoral disorders

The results of 50 arthroscopic lateral releases are reported. The average follow-up period was 36 months with a range of 18-52 months. Satisfactory results were achieved in 71% of 21 patients with patellar pain alone and in 76% of those (Betz RR, Lonergan R, Patterson R. The percutaneous lateral retinacular release Orthopaedics 1982;5:57-62) with instability. Patients with patellofemoral osteoarthritis or patellar dislocation were excluded from the series. Postoperative hemarthrosis occurred in 10%. Unsatisfactory results could be related to incomplete release, severe chondromalacia, or insufficient rehabilitation. Lateral release is capable of producing high rates of success with a low incidence of complication when used to treat patellar pain with tight retinaculum, patellar instability, and subluxation.

A biomechanical analysis of solvent-dehydrated and freeze-dried human fascia lata allografts. A preliminary report

This study compares the basic mechanical properties of two groups of commercially available fascia lata allografts processed by different means (solvent-dehydrated and sterilized via gamma radiation, and freeze-dried without secondary sterilization). The results reveal significantly (P less than 0.05) higher stiffness, higher maximum load to failure, and higher maximum load per unit width of graft with the solvent-dried as opposed to the freeze-dried fascia lata. Subsections of individual solvent-dried specimens were also more uniform in their mechanical properties than those of the freeze-dried allografts.

CLINICAL RELEVANCE

Fascia lata is used as a graft material in a variety of orthopaedic procedures. Allograft fascia lata offers an increased cross-sectional area of material and eliminates the morbidity associated with the harvesting of autologous tissues. However, the structural uniformity of such large grafts has been questioned. Processing techniques used in the sterilization and storage of such grafts is varied and represents a potential source of variation in the mechanical properties of allograft specimens. The results of this study suggest that a commercially available solvent-dehydrated form of fascia lata provides a more suitable grafting material than freeze-dried specimens obtained from tissue banks.

Proprioception Following Anterior Cruciate Ligament Reconstruction

Injury to the anterior cruciate ligament (ACL) is thought to disrupt joint afferent sensation and result in proprioceptive deficits. This investigation examined proprioception following ACL reconstruction. Using a proprioceptive testing device designed for this study, kinesthetic awareness was assessed by measuring the threshold to detect passive motion in 12 active patients, who were 11 to 26 months post-ACL reconstruction, using arthroscopic patellar tendon autograft (n=6) or allograft (n=6) techniques. Results revealed significantly decreased kinesthetic awareness in the ACL reconstructed knee versus the uninvolved knee at the near-terminal range of motion and enhanced kinesthetic awareness in the ACL reconstructed knee with the use of a neoprene orthotic. Kinesthesia was enhanced in the near-terminal range of motion for both the ACL reconstructed knee and the contralateral uninvolved knee. No significant between-group differences were observed with autograft and allograft techniques.

Occurrence of free nerve endings in the soft tissue of the knee joint. A histologic investigation

We present a comprehensive histologic study of neurologic structures in 18 static and dynamic knee structures of 8 cadaveric knees. Qualitative and quantitative measurements of the incidence of free nerve endings in the structures were recorded. The highest amounts of afferent nerve fibers type IVa were found in the retinacula, the patellar ligament, the pes anserinus, and in the ligaments of Wrisberg and Humphry; the lowest amount was found in the anterior cruciate ligament. There is a positive correlation between the number of mechanoreceptors per standardized area unit and the clinical presentation of certain knee disorders.

Allograft anterior cruciate ligament reconstruction in a sheep model. The effect of synthetic augmentation

The purpose of this study was to assess the effect of synthetic augmentation of a bone-patellar tendon-bone allograft on the basis of biomechanical, morphologic, and histologic evaluation. The anterior cruciate ligament was reconstructed in the left knee of 66 adult sheep. Half the knees received bone-patellar tendon-bone grafts alone, while the other half were augmented. All of the knees, including the contralateral controls, had gross and histologic examination, hydroxyproline assay for collagen content, and biomechanical testing in groups at 0, 4, 16, and 52 weeks postoperatively. Biomechanical testing included anteroposterior translation, ultimate tensile strength, energy to failure, stiffness, and mode of failure. Eight fresh bone-patellar tendon-bone allografts were compared to eight cryopreserved bone-patellar tendon-bone allografts for baseline data on the effects of the cryopreservation. Cryopreservation did not have any effect on graft characteristics. Gross and histologic examination did not reveal any significant difference between the augmented and nonaugmented groups at any of the time periods. In addition, hydroxyproline content of the allograft was not altered by augmentation throughout the study period. Biomechanical laboratory evaluation demonstrated the augmented group had significantly reduced anteroposterior translation (P less than 0.05) at 52 weeks compared to the nonaugmented group. The ultimate tensile strength was significantly higher (P less than 0.05) in the augmented group at 4 weeks, but at 52 weeks both groups had attained only 50% of the normal anterior cruciate ligament strength. Stiffness and energy to failure were similar in both groups at all time periods. From the results of this study, synthetic augmentation appears to improve initial strength and prevent late allograft laxity while allowing normal remodeling processes to occur in the bone-patellar tendon-bone allograft anterior cruciate ligament reconstruction.

Innervation of the canine cruciate ligaments. A neurohistological study

A search for mechanoreceptors within the substance of the cruciate ligaments was undertaken using the modified gold-chloride technique. Abundant Pacinian, Vater-Pacini, Ruffini end organs and Ruffini-type receptors were found within the substance of the anterior and posterior cruciates. The receptors were innervated by axons of 5 to 10 micrometers in diameter penetrating from the synovium investing the ligaments. The findings support the contention that the cruciate ligaments have important mechanoreceptive and proprioceptive functions.

Neurohistological findings after experimental anterior cruciate ligament allograft transplantation

A multiplicity of surgical operations have been developed in an attempt to achieve satisfactory function after anterior cruciate ligament (ACL) repair. None of these procedures have been able to duplicate the fiber organization, anatomy of the attachment site, vascularity, or function of the ACL. Eighteen foxhounds received a deep-frozen bone-ACL-bone allograft and a ligament augmentation device. Neurohistological changes were evaluated 3, 6 and 12 months following implantation. The modified silver impregnation method and gold chloride technique were used to examine the presence of nerve endings and axons. Two morphologically distinct mechanoreceptors were identified and classified as free nerve endings and Golgi-like tendon receptors respectively. Fine nerve endings frequently ramified freely into ligament collagen bundles. Nerves and blood vessels were commonly associated. As in normal ACLs, both neuroreceptor types were mostly located near the surface of the allografts and at the two bony attachments. This study demonstrated the first histological evidence of viable mechanoreceptors and free nerve endings in transplanted ACL allografts, not previously reported in other ACL substitutes used for ACL reconstruction. Particularly importantly for postoperative rehabilitation, this technique may allow the reconstruction of the proprioceptive functions of normal ACLs.

Mechanoreceptors in the posterior cruciate ligament. Histologic study on cadaver knees

The purpose of the study was to identify mechano-receptors in the healthy, human posterior cruciate ligament. Ten ligaments from 10 fresh cadavers were studied with light microscopy. In addition to free nerve endings, two types of encapsulated mechanoreceptors were identified. They were located at the femoral and tibial attachments, and on the surface of the ligament. These findings support the hypothesis that the posterior cruciate ligament has an anatomic basis for a discriminating afferent flow of nerve impulses to the central nervous system. Therefore, its neural network may play a role in regulating the contraction of muscle groups that are fundamental to knee stability.

Innervation of the human knee joint by substance-P fibers

Anterior knee pain is a frequent musculoskeletal complaint affecting all ages, both sexes, athletes, and nonathletes alike. Numerous theories have been proposed regarding its etiology including patellar malalignment, quadriceps insufficiency, subluxation, quadriceps muscle tightness, and chondral defects. However, the mechanism by which these factors produce this pain is not clear. Knowledge of the distribution of nociceptive nerve fibers around the knee would seem to provide insight in treating these painful conditions. Eleven human patellae--eight specimens from patients with degenerative patellofemoral disease and three normals--were evaluated. Immunohistochemical techniques using monoclonal antibody to substance-P were employed to identify nociceptive fibers. Substance-P is a nociceptive neurotransmitter found in afferent nerve fibers. Substance-P fibers were isolated in the retinaculum, fat pad, periosteum, and subchondral plate of patellae affected with degenerative disease. This study demonstrates that selective tracting of nociceptive pain fibers is possible around the knee both in soft tissue and, in some circumstances, bone. The subchondral plate of normal patellae did not demonstrate erosion channels, but those with chondral defects from degenerative disease did. Nociceptive fibers found in these defects may explain the origin of symptoms in some patients. The distribution of substance-P nerve fibers in the soft tissues around the knee suggests that denervation may be the mechanism by which surgical procedures for anterior knee pain produce favorable results.

Innervation of the anterior cruciate ligament

The innervation of 21 human anterior cruciate ligaments (ACL) obtained at autopsy or during operation was studied by light microscopy. Nerves and nerve endings were found in the synovium and interfascicular connective tissue. The nerves were myelinated and/or unmyelinated and had terminal nerve structures with free nerve endings which provide nociception and supply the blood vessels, Ruffini corpuscles and Pacini corpuscles, which are mechanoreceptors in the ligaments.

Reflex actions of knee joint afferents during contraction of the human quadriceps

(1) The spinal reflex actions of afferents stimulated by knee joint distension have been investigated in man. (2) Cannulation of the knee and infusion of saline raised intra-articular pressure, especially during quadriceps contraction. High pressures did not induce any sensation of pain. Pressure was taken as an index of joint proprioceptor activation. (3) Increased pressure progressively depressed the quadriceps H-reflex, both at rest and during quadriceps contraction. There was no indication of a threshold pressure for this inhibitory action. (4) It is concluded that joint distension inhibits quadriceps motoneurons through spinal pathways that still operate during voluntary contraction. These pathways could thus contribute to pathological weakness after joint injury. (5) Joint distension produced spatial facilitation of non-reciprocal inhibition of quadriceps H-reflexes from afferents in the tibial nerve.

Substance P-, calcitonin gene-related peptide- and C-flanking peptide of neuropeptide Y-immunoreactive fibres are present in normal synovium but depleted in patients with rheumatoid arthritis

By means of antisera to cytoplasmic components of nerve fibres and neuropeptides which are known to be present in sensory or sympathetic nerves we have examined the distribution of both total and different types of nerve fibres in normal and inflamed human synovial tissue. Samples of synovia were obtained at surgery from five normal and five rheumatoid patients (age range 10-77 years). In order to map the overall neural innervation of the synovium, antiserum to the general neuronal marker protein gene product 9.5 was employed. Substance P and calcitonin gene-related peptide antisera were employed to identify sensory fibres and antisera to the C-flanking peptide of neuropeptide Y to distinguish sympathetic nerves. In normal synovium protein gene product 9.5-immunoreactive fibres were numerous, in particular, the vasculature was densely innervated. Free protein gene product 9.5-immunoreactive fibres were less numerous but were present in all synovia examined, and in many cases these extended to the intimal layer. Neuropeptide immunostaining was predominantly found in perivascular networks. Fibres immunoreactive for the C-flanking peptide of neuropeptide Y were exclusively located around blood vessels whereas free fibres were immunoreactive for substance P or calcitonin gene-related peptide. As with free protein gene product 9.5-immunoreactive fibres, fibres expressing substance P or calcitonin gene-related peptide immunoreactivity were often seen in the intimal cell layer. In rheumatoid arthritis a similar innervation to that seen in normal synovium was apparent in the deep tissue but fibres immunoreactive for protein gene product 9.5, the C-flanking peptide of neuropeptide Y, substance P or calcitonin gene-related peptide were not visible in the more superficial tissues or the intimal cell layer. In addition, immunostaining of neuropeptides in the deep tissue was weaker in the diseased tissues than in normal controls. The data unequivocally demonstrate that synovial tissues are richly innervated and confirm the presence of both sensory and sympathetic nerves. The absence of nerves which innervate the superficial synovium in rheumatoid arthritis might suggest that there is increased release of substance P, calcitonin gene-related peptide and the C-flanking peptide of neuropeptide Y, reducing the stores in the nerves to levels below that detectable by immunocytochemistry. However, since protein gene product 9.5-immunoreactive nerves were not seen in the inflamed tissue it is probable that synovial growth outflanks neural growth and consequently as the disease progresses neural structures become restricted to deeper tissues.(ABSTRACT TRUNCATED AT 400 WORDS)

A neurogenic mechanism for symmetrical arthritis

Human synovium is richly innervated by autonomic and sensory nerve fibres, many of which contain neuropeptides. The hypothesis is that, in addition to a sensory role, some of these fibres modulate the response of the synovial membrane to a variety of noxious stimuli by releasing these peptides. Synovial damage results in acute inflammation in the damaged joint and a neurogenically mediated infiltrate of inflammatory cells in the contralateral joint. These cells might protect the contralateral synovium from injury similar to that in the damaged joint. An increased response would lead to synovitis and symmetrical disease.

A neurosensory hypothesis of ligament function

Ligaments are generally viewed as passive structural elements. Virtually all treatments for torn ligaments are based upon a structural paradigm. However, there is considerable evidence to suggest that ligaments function as neural sensors to facilitate supportive reflex contractions of muscles. It is hypothesized that injury to ligaments disrupts the neural apparatus as well as the structural support. Dysfunction following injury may result as much from neural injury as from structural instability. In some patients, "neural adaptation" likely occurs, while in others it does not. Since current treatments for ligament injuries (all of which are based on structure) are not uniformly successful, we need to develop methods to distinguish the neurally impaired patient from the structurally impaired, and to develop methods to treat the former.

Thigh musculature in relation to chronic anterior cruciate ligament tear: muscle size, morphology, and mechanical output before reconstruction

Eighteen male patients who had untreated chronic ACL rupture were studied in order to evaluate thigh muscle size, morphology, and isokinetic performance of the quadriceps muscle. Computed tomography disclosed a 5.1% mean atrophy of the quadriceps (P less than 0.05), 2.1% slight hypertrophy of the hamstrings (P less than 0.05), and also nonsignificant changes of all other muscle areas of the injured thigh. Muscle morphology (m. vastus lateralis) was normal in 11 biopsy specimens, whereas minor abnormalities (irregular shape or hypotrophy) could be seen in the rest. Isokinetic mechanical output of the knee extensors was 71% to 87% of that of the noninjured limb (P less than 0.01), and the mechanical output corrected for differences in quadriceps cross-sectional area was significantly lower in the injured than the uninjured limb. As there were no significant correlations between isokinetic performance and muscle size or qualitative morphology or morphometric data, the strength decrease cannot be explained by muscle atrophy or structural changes per se. We conclude that nonoptimal activation of the muscles during voluntary contractions is probably the most important causative mechanism of the strength decrease found in patients who have chronic symptomatic ACL tear.

Fusimotor neurones can be reflexly influenced by activity in receptor afferents from the posterior cruciate ligament

Recordings were made simultaneously from 2-4 primary muscle spindle afferents from triceps surae and/or posterior biceps and semitendinosus muscles in cats anaesthetized with alpha-chloralose. It was demonstrated that stretch of the posterior cruciate ligament of the ipsilateral knee could cause changes in dynamic and/or static sensitivity of these afferents to sinusoidal stretching. The changes were due to reflex actions of stretch/tension-sensitive receptors in the cruciate ligaments onto fusimotor neurones. It is concluded that the cruciate ligaments may play an important 'sensory' role and that they may participate, via reflex actions on the gamma-motor-muscle spindle system, in the regulation of muscular stiffness of the knee joint, and thereby of the knee joint stability.

Anatomy of the posterior cruciate ligament. A review

PCL injuries are major injuries of the knee. Most of the literature on PCL injury has focused on mechanism of injury, diagnosis, and treatment. We are presenting a review of the anatomy of the PCL. Different portions of the PCL are taut at different degrees of knee flexion and extension. The PCL, thus, along with the ACL, contributes to the "screwhome mechanism" of the knee. The anatomy of the meniscofemoral ligaments (ligaments of Wrisberg and Humphrey) reveals the intimate relationship among the PCL, the popliteus muscle, and the lateral meniscus. Understanding the anatomy of the PCL is important in the diagnosis and treatment of ligamentous injuries and also in total knee arthroplasty.

Proprioception in the anterior cruciate deficient knee

Proprioception was quantified in a group of patients who had documented complete ACL tears. Threshold to detection of passive change in position of the knee was measured using a well-described test. Eleven patients with arthroscopically proven complete ACL tears and findings consistent with moderate to severe anterolateral rotatory instability were tested. Testing was done within the 30 degrees to 40 degrees range of knee flexion. Patients were blindfolded and the injured and uninjured knees were tested in random sequence so that the normal knee could serve as an internal control. Testing was also done in a blind manner, i.e., the examiner did not know which knee had been injured. An age-matched control group underwent identical testing. Potentially significant variables such as age, time from injury, and degree of rehabilitation as measured by thigh circumference and isokinetic testing of the knee were included in a multivariate analysis. Control subjects demonstrated virtually identical threshold values between their two knees, the mean variation being less than 2%. The test group, however, showed a significantly higher mean threshold value for the injured versus the noninjured knee (P less than 0.01), the mean variation being over 25%. Multivariate analysis demonstrated that changes recorded in the proprioception of the injured knee were attributable to the loss of the ACL rather than to other variables. Patients who have complete ACL tears and moderate to severe rotatory instability may also experience a decline in proprioceptive function of their knee.

Mechanoreceptors in articular tissues

The morphology, distribution, and function of mechanoreceptors in joint capsules, ligaments, knee-joint menisci, and articular disks of the temporomandibular joints of animals, including humans, have been reviewed. In addition to free nerve endings, three types of joint receptors are present in most animal joints: 1) a Ruffini-like receptor situated in the capsule, 2) a Golgi tendon organ situated in a ligament; and 3) the encapsulated Pacinian-like corpuscle. In the anterior cruciate ligament, nerve fibers enter from the subsynovial connective tissue and terminate in receptors. Most of the receptors are found in the distal portion of the ligament. In the meniscus, nerves penetrate the outer and middle one-third of the body and the horns from the perimeniscal tissue, with a greater concentration at the horns. In the temporomandibular articular disk, the mechanoreceptor density is greatest at the periphery and progressively decreases toward the center. If a joint has an intra-articular structure, mechanoreceptors undoubtedly are present within it. The concentration of mechanoreceptors appears greater in areas related to the extremes of movement and probably represents the first line of defense in sensing these extremes. These afferent discharges elicit support from discharging mechanoreceptors located in the joint capsule and subsequently from those in the surrounding muscles. This total afferent output alerts the central nervous system of impending injury, which can then be averted through reflex mechanisms.

Arthroscopic meniscal repair with two-year follow-up: a clinical review

The potential for healing of meniscal tissue has been historically underappreciated, but is currently more widely acknowledged. We have reviewed our experience with arthroscopic meniscal repair in 29 patients who had had a minimum of 2 years' follow-up. Between September 1983 and November 1986, 31 patients who had undergone arthroscopic meniscal repair with a minimum of 2-years' follow-up were identified. Of the 31 patients, 29 were available for additional follow-up. The patient population averaged 31 years of age, with 15 men and 14 women. Utilizing a closed arthroscopic cannulated technique, 16 lateral and 15 medial menisci were repaired. The majority of lesions were vertical bucket-handle tears involving the posterior horn and averaged 2.5 cm in length. Of the 31 tears, 29 were in the red-red or red-white zones. Clinical healing was present in 27 (87%) of the 31 repaired menisci. Nine patients underwent relook arthroscopy at which time healing was confirmed in eight, and a retear noted in one. Four reruptures occurred and the menisci required removal. Of the 29 patients, 16 had concomitant anterior cruciate ligament injuries ranging from partial tears to complete disruptions. Seven patients underwent immediate or delayed anterior cruciate ligament stabilization. Healing occurred in six of the seven patients whose anterior cruciate ligaments had been reconstructed. Among those patients with reruptures, chronic anterolateral rotatory instability was identified as a significant risk factor for rerupture. A complication rate of 13% was noted. Three patients underwent manipulation under anesthesia for postoperative ankylosis and one patient experienced a transient saphenous nerve neuropraxia.(ABSTRACT TRUNCATED AT 250 WORDS)

gamma-Aminobutyric acid in synovial membrane of rat knee joint

gamma-Aminobutyric acid (GABA) content was measured, and the release of GABA was studied in the synovial membrane of the rat knee joint. GABA content of the synovial membrane was 20.1 nmol/g tissue. Ten days after unilateral dissection of the sciatic nerve, femoral nerve or both nerves, the GABA contents of the ipsilateral membrane were 13.8, 14.6 and 7.8 nmol/g tissue, respectively. High K+ evoked the Ca2+-dependent release of [3H] GABA from the synovial membranes of intact rats preloaded with [3H] GABA, but did not evoke release from the membrane ipsilateral to the dissection of both sciatic and femoral nerves. Evoked release of [3H] GABA was obtained in the synovial membrane preloaded with [3H] GABA in the presence of beta-alanine, but not in the presence of 2,4-L-diaminobutyric acid. These results indicate that GABA is present in the neuronal elements of the synovial membrane of the rat knee joint.

A double blind trial of NSAID versus placebo during rehabilitation

Forty patients participated in a randomized, parallel, double blind study of piroxicam, 20 mg daily, versus placebo, given orally for 10 days following open partial meniscectomy. On day 1, 3, 7, 11, and 21 after surgery the following parameters were studied: quadriceps torque measured isokinetically; patients' assessment of pain; active and passive range of motion measured with goniometer; degree of swelling and irritation of the operated knee; and efficacy of the medication. The mean values for all parameters, except for pain assessment, were in favor of the piroxicam group. This difference was most marked on day 7 and 11 and on these days highly significant. Our findings indicate that piroxicam may be able to improve early postoperative rehabilitation.

The role of joint receptors in human kinaesthesia when intramuscular receptors cannot contribute

1. Kinaesthetic acuity was tested at the distal interphalangeal joint of the middle finger when the hand was postured so that the joint was effectively disengaged from its muscular attachments. Subjects were required to detect the direction of 5 deg movements applied at different angular velocities from a mid-position under control conditions, after intra-articular injection of a plasma expander and after intra-articular injection of a local anaesthetic. 2. Kinaesthetic performance was enhanced after the injection of a plasma expander and deteriorated after injection of local anaesthetic. This deterioration could not be explained by spread of the local anaesthesic from the injection site on the dorsum of the joint. 3. The results suggest that the discharge of joint receptors can produce perceived signals of joint movement. Under normal conditions these receptors may duplicate the kinaesthetic input from muscle spindle endings.

The relationship of injuries of the leg, foot, and ankle to proximal thigh strength in athletes

Rehabilitation programs designed to restore leg, ankle, and foot function following injury frequently ignore the proximal muscles. During athletics, these knee, hip, and trunk muscles derive much of their functional power from the foot and ankle. They also serve to integrate distal segment motions into a total movement pattern such as jumping, running, or kicking. The linkage system, which is a theoretical concept, describes the normal biomechanical and physiological interactions between proximal and distal musculoskeletal structures. Immobilization or injury of distal segments interrupts the normal generation, summation, and transmission of muscular forces across joints. Adequate measures must be taken to properly assess proximal structures for weakness and tightness and to prescribe specific exercises to prevent the migration of the effects of injury away from the involved segment.

Patellar instability: treatment by arthroscopic electrosurgical lateral release

We reviewed the results of arthroscopic lateral release using electrosurgery in 39 patients (45 knees) with a history of recurrent patellar subluxation or dislocation. The average follow-up time was 28 months (range, 24-36). At follow-up, the patients had decreased swelling, instability, and pain. There was an improvement in flexion activities, sports participation, and overall functional ability. Only 20% of the knees had completely normal physical findings: 11.1% of the knees were rated as excellent; 64.4% were improved; and 24.5% were poor. Dislocators had more frequent poor results. The complication rate was 4.4%. There were no postoperative hemathroses. One patient was considered a surgical failure. The technique yields results comparable with those of open extensor realignment procedures and avoids the complications inherent to lateral release in general. The place for this procedure in patellar instability is well-documented.

Assessing Quadriceps Femoris Muscle Bulk with-Girth Measurements in Subjects with Patellofemoral Pain

This study was conducted to determine the validity of estimating quadriceps femoris muscle bulk with girth measurements in individuals with chronic unilateral patellofemoral pain. Testing included measurements of thigh girth and B-mode ultrasound scans of quadriceps femoris muscle thickness in 26 males and 18 females. Comparison of the control and symptomatic limbs demonstrated significant reductions in muscle thickness in both the male (p < 0.000) and female (p < 0.007) subjects. No significant differences were noted at either the midthigh or suprapatellar girths between limbs, except in the male subjects at the midthigh site (p < 0.006). Estimating muscle atrophy with girth measurements was more accurate in the male versus the female subjects. Clinicians should realize that very small reductions in thigh girth (1%) may be an indicator of significant reductions in muscle bulk (13%), in individuals with prolonged joint pain and disability. Even though the assessment of quadriceps muscle atrophy with girth measurements is somewhat inaccurate, girth measurements probably remain clinically useful. J Orthop Sports Phys They 1987;9(5):177-183.

Reduction of pain inhibition on voluntary muscle activation by epidural analgesia

The influence of postoperative pain on muscle function, and the possible effect of local anesthetics on the normal muscle function are discussed. The integrated EMG (IEMG) during maximum voluntary contraction of the quadriceps muscle was registered in ten patients the day after undergoing reconstruction of the anterior cruciate ligament. Recordings were taken before, 5, 12, and 20 min to 25 min after epidural injection of 20 ml of 0.25% lidocaine with adrenaline (2.5 micrograms/ml). As pain gradually subsided, IEMG increased a mean of 2,728% 20 min to 25 min after injection (range 425% to 10,068%), compared to initial recordings before anesthesia. This indicates that pain relief plays a significant role in the ability to normally activate the quadriceps muscle after open knee surgery. Neither the Hoffman (H-)reflex, nor maximum voluntary isokinetic muscle torque was appreciably affected by epidural injection of dilute local anesthetics, as tested on two healthy volunteers. Infiltrations of local anesthetics into the distal part of the quadriceps muscle did not affect maximum voluntary isokinetic knee extension torque. From the experiments performed we conclude that it is possible to selectively block pain by injections of local anesthetics into the epidural space, without interfering with normal muscle function. It might thus be possible to prevent some of the postoperative muscle atrophy by using a continuous epidural analgesia for two to three days following surgery, and starting an early active physical therapy program.

Dynamic joint control training for knee ligament injuries

The purpose of this study was to introduce dynamic joint control training and to assess its effects in improving neuromuscular coordination of injured knees using the Kin-Com Isokinetic Dynamometer. Although four patients had a sensation of "giving way" on one knee, all eight knees were trained for 3 months using unstable boards with added sudden force given by a therapist. The training group (four patients) was examined during four sessions and the control group (five subjects) was examined during three sessions within a 3 month period. All subjects were instructed to react to the sudden forward movement of the input arm of the Kin-Com Isokinetic Dynamometer with contraction of the hamstring. Results of the first and final trials of peak torque time (PTT) and rising torque value (RTV) of the hamstring between the training and control groups showed significant improvement. There was no correlation between isometric muscle strength (IMS) and PTT in the total 76 sessions. There is a strong implication that simple muscle training does not increase the speed of muscular reaction but dynamic joint control training has the potential to shorten the time lag of muscular reaction.

Muscle fiber atrophy in the quadriceps in knee-joint disorders. Histochemical studies on 112 cases

In order to determine whether there is a different susceptibility of muscle fiber types in the m. vastus lateralis (VL) in knee-joint disorders, histochemical studies were performed on 112 cases. Anterior cruciate ligament (ACL) injuries affected 51 patients; ACL injuries associated with meniscus (ACL + M) injuries affected 29. Twenty-five patients had sustained meniscus injuries and seven had injuries of the collateral ligaments (CL). Fifty-two were athletic and 60 were not. On each biopsy, fiber-type distribution was obtained and the degree of atrophy of each fiber type was estimated from two parameters, the mean diameter and the percentage of atrophied fibers. The distribution of type-1 fibers averaged 38.0% +/- 12.0%. There were no significant differences among disorders in the distribution of type-1 fibers. Both parameters of fiber atrophy revealed a difference in susceptibility between type-1 and type-2 fibers. Atrophy of type-1 fibers was found only in ACL and ACL + M injuries. Type-2 fibers were atrophied in all four disorders. Atrophy of type-2 fibers could be a nonspecific change due to the inactivity of the VL, but type-1 fiber atrophy may relate specifically to the condition of ACL insufficiency.

Mechanoreceptors in the human anterior cruciate ligament

This study was undertaken to identify and quantitate mechanoreceptors in the human anterior cruciate ligament (ACL). Ligaments from six human subjects were obtained at autopsy, cut into cross-sectional segments 1.0-1.5 cm thick, and kept oriented as to the femoral and tibial attachments. The segments were stained in bulk by using a modified gold chloride method, frozen, and sectioned on a sliding microtome at 100 microns. The sections were floated in alcoholic gelatin, mounted on slides, dehydrated, and coverslipped. Serial sections were studied with the light microscope and receptors were photographed. Cross-sectional maps of every tenth section were made outlining the periphery of the ACL and the receptors within that section. With these maps, a computerized, morphometric analysis of the ACL was done, thus obtaining the percentage of receptors in each section and in each ACL. In addition to free nerve endings, two morphologically distinct mechanoreceptors were identified: (1) Ruffini end organs and (2) Pacinian corpuscles. Preliminary morphometric analyses show that populations of mechanoreceptors are greater at the femoral and tibial ends of the ligament and constitute approximately 2.5% of the ligament. Based on these findings the human ACL has the anatomic basis for a discriminating afferent outflow to the central nervous system.

Innervation of synovial membrane and meniscus

Substance P-immunofluorescent nerves, which are closely connected to pain transmission, were shown in human knee synovial membrane and menisci. Both tissues also contained enkephalin-immunofluorescent nerves, which are probably involved in the modulation of pain transmission. Previous suggestions on the presence of nociceptive receptors in these non-cartilaginous joint structures, made on a histological basis, are thus confirmed by a specific immunohistochemical method.

Patellalgia

In brief: Knee pain relating to or arising from the patellofemoral articulation is common in athletes. While direct trauma can cause this pain, patellofemoral malalignment and/or tracking problems seem to be its major source. This paper reviews the functional anatomy of the patella and describes the diagnostic and treatment procedures recommended for investigating and treating this condition. Most patients improve after an initial course of conservative treatment. Proximal or distal realignment may be surgically performed in patients who don't respond to conservative treatment. Patellectomy leaves some weakness in the quadriceps and should be used only as a last resort.

Sports injuries of the knee ligaments--a prospective stress radiographic study

Forty-six patients were entered into a prospective clinical and stress radiographic study done to assess the value of acute surgical treatment of injuries to the knee ligaments sustained during sports activities. After an average follow-up period of 5 1/2 years (range 4-6 1/2 years) medial instability was found only in two patients, both of whom were in the group with isolated rupture of the medial collateral ligament. Nine of the 29 patients in this group developed rotatory instability, but it was moderate and did not give rise to symptoms. Among the 17 patients with either injuries to the anterior cruciate ligament or combined injuries, anterior drawer instability persisted in seven, with an insufficient functional result in five. None of these 17 patients were able to resume competitive sport. Those patients who had not exercised physically just before the injury proved to have a significantly greater total instability than those who had. Therefore, routine limbering-up is recommended before sports activities.

The vascular and nerve supply of the human meniscus

Twenty-three fresh, cadaver knees were studied to evaluate details of the vascular and nerve supply of the menisci in humans. Vascularity was investigated using dye and latex injections, and the nerve supply was studied microscopically using a variety of special stains. Vessels arise mainly from medial and lateral inferior and middle geniculate arteries. Radial branches from a perimeniscal plexus enter the meniscus at intervals, with a richer supply to the anterior and posterior horns. Vessels supplying the body are limited to the peripheral one-third, except in the fetus. There is an avascular area adjacent to the popliteus tendon. The perimeniscal tissue is richly innervated. Most nerves are associated with vessels. Smaller nerves and axons run radially in convoluted patterns. Single axons course through the perimeniscal tissue, and many nerves are seen in the interstitial tissue of the outer one-third of the meniscus and in the anterior and posterior horns. The inner two-thirds has no nerve fibers.

Diagnostic arthroscopy and longitudinal open lateral release: a safe and effective treatment for "chondromalacia patella"

Lateral release is a reliable component of any surgical treatment of patellofemoral dysfunction or "chondromalacia patella," good to excellent results in approximately 80% of cases having been reported by numerous investigators. This study confirms the efficacy of the procedure and highlights the features of the open technique as compared with the arthroscopic method. We advocate diagnostic arthroscopy for complete evaluation of the joint. Particular attention is drawn to the anatomic structures that must be divided and the care taken to secure hemostasis to optimize results. Since no correlation was found between the severity of chondromalacia and the final results, this study casts doubt on the value of shaving the rough articular surface.