Medial Patellar Ligament Research Articles

Normal ultrasonographic anatomy and injury of the patellar ligaments in the horse.

The purposes of this study were to investigate the ultrasonographic appearance of the patellar ligaments in clinically normal horses and to describe the clincical features, diagnosis and outcome of patellar ligament injury. The medial, middle and lateral patellar ligaments of 5 Thoroughbred and 5 Warmblood horses, free from lameness and in full work, were examined ultrasonographically. The ligaments were all of uniform echogenicity and each ligament was fairly consistent in its shape. The size of the ligaments of the Warmblood horses tended to be bigger than the lighter bodyweight Thoroughbred horses. The bone surfaces were smooth at the ligament insertions on the patella and tibia. Nine horses, including 7 showjumpers, were identified with a unilateral hindlimb lameness associated with ultrasonographic evidence of damage to one or more patellar ligaments. Four horses had primary desmitis of the middle patellar ligament, one of which had concurrent intermittent upward fixation of the patella and a second had abnormal movement of the patella. Two additional horses had desmitis of the middle patellar ligament associated with previous medial patellar desmotomy. Two horses had desmitis of both the middle and lateral patellar ligaments, and one horse had desmitis of the lateral patellar ligament alone. None of the 9 horses were able to return consistently to their former level of competition. Careful clinical evaluation and ultrasonographic examination of the patellar ligaments should be considered in horses with hindlimb lameness of otherwise undetermined cause.

Fine sensory innervation of the knee joint capsule by group III and group IV nerve fibers in the cat.

Afferent group III and IV nerve fibers of the knee joint markedly differ in their responsiveness to mechanical stimulation, which may be reflected in the structure and location of their terminals. Therefore, in sympathectomized cats, the fine afferent innervation of the knee joint capsule was studied via ultrastructural three-dimensional reconstructions over distances of up to 300 microns. Small peripheral nerves and "free" (noncorpuscular) sensory nerve endings were found in a superficial layer of the outer fibrous part of the capsule, in the patellar retinaculum, and in the outer and inner surface layers of the medial collateral and patellar ligaments. Group III nerve fibers showed a proximal myelinated portion inside the nerve, an intermediate portion that lacks a myelin sheath and is only surrounded by perineurium, and a distal portion outside of the perineurium that forms the sensory ending proper. Group IV fibers showed only two distinct portions, an intraperineurial (proximal) and an extraperineurial (distal) portion without any further morphological differences. Outside of the perineurium, a network formed by Schwann cells ("Schwann cell reticulum") provides a pathway for the distal portion of the sensory axons. No distinct subgroups of the sensory terminal fibers could be defined according to the configuration of the Schwann cells and the nerve fiber terminals. Sensory terminals were located adjacent to different structures such as venous and lymphatic vessels, fat cells, and collagenous fibers. Distinct parts of the same terminal nerve fiber were found in close contact to a vessel wall; others were surrounded by dense collagenous tissue. Close to sensory endings, mast cells and mast cell-like cells were frequently found, indicating a functional relationship.

ULTRASONOGRAPHY OF THE EQUINE STIFLE

Ten stifles from 5 clinically sound adult horses were scanned by high‐resolution ultrasound. Normal anatomic structures seen consistently included the subcutaneous tissue, the medial, middle and lateral patellar ligaments, the medial and lateral collateral ligaments, the femoral trochlear ridges, and menisci. Cruciate ligaments could not be visualized in the standing horse. Four stifle specimens obtained from 2 of these normal horses at necropsy were scanned in a water bath to create optimal technical conditions. The sonographic appearance of stifle specimens was similar to that found in live horses. Results from ultrasonographic examination of 3 horses with stifle abnormalities were described to illustrate some applications of ultrasonography in the evaluation of the equine stifle. In these horses, ultrasound was a valuable diagnostic tool to study joint effusion, synovial thickening, articular cartilaginous and subchondral defects, and soft tissue/bony injuries.

Arthroscopic examination of the femorotibial joints of horses.

A technique for satisfactory arthroscopic examination of the lateral and medial femorotibial joints of the horse is described. The entry portal is made between the middle and medial patellar ligaments with the horse on its back and the stifle flexed. This position allows easy access to view the intercondylar eminence of the tibia. From this reference point, examination of all but the most caudal and medial structures of the joints are possible by manipulating the sleeve and telescope and maintaining joint distention. In a series of 20 examinations, iatrogenic trauma was recognized only once.

膝周辺骨腫ようにおける患肢温存療法の経験

We had experienced three cases of limb-salvage operation on the knee joint. The first case was a 9-year-old female. She had a osteosarcoma of her right femur. Following 5 times of CDDP 100mg/m2, she underwent local wide excision and replacement of her femoral distal region with the ceramic implant. 31 months postoperatively she was free from disease, but her right leg was shortened by 5cm, and medio-lateral instability was moderate. The evaluation by Enneking (1982) was poor. The second case was a 12-year-old female. She had an aneurysmal bone cyst of her right femur. She underwent curettage of the femoral lesion. The lesion was again curetted and filled with the bone-cement. But the recurrence was shown on the X-ray. She was treated by excision and replacement of her knee joint with the ceramic implants. 23 months after the last operation, she had a good function of her right knee joint. The evaluation by Enneking was fair. The third case was a 74-year-old male. He had a osteosarcoma of his right tibia. Following two times of ADR 50mg/body (ia), He underwent the local wide excision, replacement of his right tibial proximal region and reconstraction of the medial and lateral collateral ligaments and patellar ligament. 17 months postoperatively, evaluation by Enneking was fair. However, he died of disseminated intravascular coagulation after the operation for a metastasis of the 7th thoracic vertebral body.

Observations on the healing process of the medial patellar ligament after desmotomy in cattle.

Macroscopic and microscopic observations were made on the healing process of cut ends in the medial patellar ligaments during a period from 7 to 201 days after desmotomy in 24 normal cattle. Lameness was not seen in any of the cattle after the operation. Adherence at the severed site was not observed in any of the samples. The connective tissue already had bound up the cut ends 7 days after the operation. The repair tissue was grossly distinguishable from the ligament and surrounding connective tissue in all samples. On the basis of gross observations, the authors divided the repair period into three stages. In the early stage, there was no significant increase in the distance between the ends of the cut ligament since the operation, in the intermediate stage the distance tended to increase, and in the last stage the distance decreased. The mean distances observed in each of the stages were 19mm±S. D. (range 17 to 23mm), 23mm±S. D. (range 13 to 33mm) and 14mm±S. D. (range 7 to 27mm), respectively. Microscopic observations, demonstrated loose connective tissues in the gap during the early stage were loose connective tissues. Thereafter, fibroblasts closely aligned in longitudinal direction in the area closest to the cut ends. This arrangement progressed gradually towards the center of the gap. In the sample taken 201 days after operation, however, the cell density in the gap was identical to that of the ligament tissue. These results suggested that connective tissues in the gap gradually changed to ligament tissues.

The effects of injection of an iodine counterirritant into the patellar ligaments of ponies: Application to stifle lameness

Patellar fixation is a common cause of lameness in horses and has been successfully treated by injection of the patellar ligaments with counterirritants. To investigate the effects of this treatment, the medial and middle patellar ligaments of 10 ponies were injected with an oil-based iodine counterirritant solution and then examined morphologically. Vacuoles of counterirritant were present in the paratenon and endotenon of the ligaments and caused severe necrosis and inflammation. At 1 day after injection, there was a marked neutrophilic infiltration which progressed to a lymphocytic infiltrate by 3 days. By 7 days, fibroplasia was present and became more organized with time. Disrupted collagen fibers and numerous, large, pale fibroblasts were present in the fasciculi, but neutrophilic infiltration was absent. The fibrous response in the fasciculi was similar to that present in the paratenon and endotenon. At 28 days, the drug was still present as lipid vacuoles in the paratenon and endotenon, and the damaged fasciculi had not regained their normal appearance. The clinical effect of this treatment was attributed to the change in size and shape of the patellar ligaments resulting from the inflammatory response.

The effects of injection of an iodine counterirritant into the patellar ligaments of ponies: Application to stifle lameness

Patellar fixation is a common cause of lameness in horses and has been successfully treated by infection of the patellar ligaments with counterirritants. To investigate the effects of this treatment, the medial and middle patellar ligaments of 10 ponies were injected with an oil-based iodine counterirritant solution and then examined morphologically. Vacuoles of counterirritant were present in the paratenon and endotenon of the ligaments and caused severe necrosis and inflammation. At 1 day after injection, there was a marked neutrophilic infiltration which progressed to a lymphocytic infiltrate by 3 days. By 7 days, fibroplasia was present and became more organized with time. Disrupted collagen fibers and numerous, large, pale fibroblasts were present in the fasciculi, but neutrophilic infiltration was absent. The fibrous response in the fasciculi was similar to that present in the paratenon and endotenon. At 28 days, the drug was still present as lipid vacuoles in the paratenon and endotenon, and the damaged fasciculi had not regained their normal appearance. The clinical effect of this treatment was attributed to the change in size and shape of the patellar ligaments resulting from the inflammatory response. Approximately 90–95% of stifle lamenesses have been attributed to problems involving the patellar ligaments, 2 which are essentially continuations of the tendons of insertion of the quadriceps femoris and biceps femoris muscles. 3 Upward fixation of the patella has long been recognized in horses in which the stifle joint becomes locked in extension, thus preventing flexion and normal advancement of the limb. 6 If forced to advance the limb, the horse may drag its toe on the ground. A more common and subtle form of this condition also occurs. A momentary fixation of the patella may occur which results in a painful, inflamed joint, but obvious locking of the stifle is not seen. 8 This problem is common in performance horses. Diagnosis of the mild form of patellar fixation can be made by standing the horse squarely with the affected stifle in extension and the patella in its most proximal position. According to Habel, 4 this is the resting position of the patella as described by Preuss and Henschel. 10 With the palm of the hand placed on the patella (left hand for left patella, right hand for right patella), the examiner forces it caudally and slightly proximolaterally (Figure 1). While pressure is maintained on the patella in this manner, the person handling the horse is instructed to move the horse ahead one step. Normally, the medial parapatellar fibrocartilage, which is considered part of the medial patellar ligament, 3 will readily disengage from the medial femoral trochlea, 4 in our clinical experience, this is not the case in conditioned horses. Medial patellar desmotomy is commonly performed on horses with patellar fixation. 6 8 1 9 This procedure has the disadvantage of interrupting the horse's training program. An infrequent but disastrous sequel is rupture of the middle patellar ligament and the resulting inability to extend the stifle joint. As an alternative, application of external blisters to the stifle was recommended many years ago. 6 9 Injection of counterirritants into the medial and middle patellar ligaments has been described. 8 This latter treatment, in conjunction with a continued exercise program, has been used successfully by one of the authors (MPB) to treat clinical cases of patellar fixation. The purpose of this study was to evaluate the histological effects of injection of an iodine counterirritant solution into the patellar ligaments of ponies and relate these changes to the apparent clinical effectiveness of this treatment in horses with patellar fixation.