Embryology of the acetabular labral-chondral complex.

Damage to and repair of the acetabular labral-chondral complex are areas of clinical interest in the treatment of young adults with pain in the hip and in the prevention of degenerative arthritis of the hip. There are varying theories as to why most acetabular tears are located anterosuperiorly. We have studied the prenatal development of the human acetabular labral-chondral complex in 11 fetal hips, aged from eight weeks of gestation to term. There were consistent differences between the anterior and posterior acetabular labral-chondral complex throughout all ages of gestation. The anterior labrum had a somewhat marginal attachment to the acetabular cartilage with an intra-articular projection. The posterior labrum was attached and continuous with the acetabular cartilage. Anteriorly, the labral-chondral transition zone was sharp and abrupt, but posteriorly it was gradual and interdigitated. The collagen fibres of the anterior labrum were arranged parallel to the labral-chondral junction, but at the posterior labrum they were aligned perpendicular to the junction. We believe that in the anterior labrum the marginal attachment and the orientation of the collagen fibres parallel to the labral-chondral junction may render it more prone to damage than the posterior labrum in which the collagen fibres are anchored in the acetabular cartilage. The anterior intra-articular projection of the labrum should not be considered to be a pathological feature.

Knee joint immobility induces Mcl-1 gene expression in articular chondrocytes.

The capacity of chondrocytes to synthesize and remodel the extracellular matrix of the articular cartilage is influenced by mechanical forces applied to joints. Either abnormally high or low loads are detrimental to articular cartilage. Experimental work on animals suggests that immobilization can alter proteoglycan synthesis and result in thinning and softening of the articular cartilage. Little is known of the effects of joint immobility on the pattern of genes expressed by chondrocytes. This study focused on the induction of Mcl-1 gene expression in a rat model of knee joint immobilization by the method of differential display PCR. Increase in Mcl-1 gene expression in chondrocytes induced by joint immobilization was confirmed by RT-PCR, Northern blotting, and immunohistochemistry. Our results indicate that chondrocytes respond to the complete absence of joint motion by expressing Mcl-1 gene. This expression may be part of a defense strategy by chondrocytes to overcome the impending chondrocyte death and cartilage degeneration induced by joint immobility.

Different levels of COX-1 and COX-2 enzymes in synoviocytes and chondrocytes during joint contracture formation.

OBJECTIVE: To measure the levels of prostaglandin endoperoxide H synthase (PGHS) isozymes (or cyclooxygenase, COX) in vivo during the development of joint contractures secondary to immobilization in rats. METHODS: Rats had one knee joint immobilized for up to 32 weeks. Three groups were compared: 47 rats had knee joints immobilized, 38 animals had sham surgery, and 13 unoperated animals served as controls. Levels of PGHS-1 and PGHS-2 enzymes were characterized in the chondrocytes and synoviocytes of the knee joint by immunohistochemistry. Immunostaining intensity was quantified by microscopy using conventional analysis. RESULTS: PGHS-1 level was lower in synoviocytes of the anterior capsule compared with shams (1.3 vs 2.0; p < 0.05). PGHS-2 level was also lower in synoviocytes of the posterior capsule (1.8 vs 2.3; p < 0.05), but higher in chondrocytes at the anterior aspect of the tibia compared with shams (1.6 vs 0.8; p < 0.05). PGHS-2 staining was increased in chondrocytes at the posterior, opposed, and anterior aspects of the tibia compared with controls (1.1, 0.6, 0.8 vs 0.2, 0.1, 0.2, respectively; all p < 0.05). CONCLUSION: Immobility induced joint contractures are characterized by a contrasting cellular pattern of PGHS enzyme levels: decreased in the synovium and increased in the chondrocytes. These findings suggest that chondrocytic PGHS isoenzymes are important in cartilage degradation of contractured joints.

Early reactions after reimplantation of the tendon of supraspinatus into bone. A study in rabbits.

In 14 rabbits we determined the origin of the cells effecting healing of the tendon of supraspinatus inserted into a bony trough. After two weeks both the cellularity of the underlying bone and the thickness of the subacromial bursa were significantly increased in the operated compared with the control shoulders. The cellularity of the stump of the tendon, however, was significantly decreased in the operated shoulders. In this model, both the underlying bone and the subacromial bursa but not the stump of the tendon contributed to the process of repair. We conclude that the medial stump should be debrided judiciously but that cutting back to bleeding tissue is not necessary during repair of the rotator cuff. Moreover, great care should be taken to preserve the subacromial bursa since it seems to play an important role in the healing process.

Synovial adhesions are more important than pannus proliferation in the pathogenesis of knee joint contracture after immobilization: an experimental investigation in the rat.

OBJECTIVE: To measure intraarticular pannus proliferation after early and prolonged joint immobility using an animal model. METHODS: Forty rats underwent unilateral immobilization of a knee joint with an internal fixator for periods of 2, 4, 8, 16, and 32 weeks. Twenty rats received sham surgery. The knee joints were harvested and processed for histological examination. The synovial intima length and the subintimal area were measured on standardized sagittal sections with image analysis software. The measurements were recorded with regard to their location (anterior or posterior; superior or inferior). RESULTS: Intra and interrater reliabilities for all measurements were > 87.9%. The synovial intima length was smaller in immobilized knees than in controls at all time points. At 4 and 32 weeks, the difference was statistically significant (p < 0.05). The differences were marked in the posterior synovium, where the intima length of immobilized knees was significantly smaller than in controls after 4, 8, 16, and 32 weeks of immobilization (p < 0.05). The subintimal area was comparable in immobilized and control knees at all time points. CONCLUSION: We standardized the quantification of intraarticular pannus in a joint contracture model after immobility of up to 32 weeks' duration. This study revealed a significant decrease in synovial intima length but no change in the subintimal area of immobilized knees compared with controls. The decrease in synovial intima length with immobility suggests that adhesions of synovium villi rather than pannus proliferation are the major pathophysiological changes leading to contracture after immobility.

Histologic evidence of degeneration at the insertion of 3 rotator cuff tendons: a comparative study with human cadaveric shoulders.

We determined on histologic examination the degree of degeneration at the insertion of 3 rotator cuff tendons in 76 cadaveric shoulders, 17 of which had a partial tear of the supraspinatus. Fiber thinning, the presence of granulation tissue, and incomplete tearing of fibers, all evidence of degeneration, were quantified separately for each tendon. Among the shoulders that were intact on macroscopy, no significant difference in degeneration score could be found. In all 3 tendons degeneration was more prominent on the articular sides compared with the bursal sides (P < .0001). The degeneration score of partially torn supraspinatus was significantly higher than that of the intact tendons (P < .0001). The extent of granulation tissue, 1 criterion of degeneration, seemed to contribute mostly to this difference. Intrinsic degeneration occurred foremost in the articular side of the rotator cuff and might constitute the primary cause of rotator cuff tearing.

Pathogenesis of soft-tissue contracture in club foot.

We investigated the pathogenesis of soft-tissue contracture in club foot, using immunohistochemistry to study 41 biopsy specimens and 12 normal deltoid ligaments from cadavers. Five biopsy specimens were studied by electron microscopy (EM) to determine the presence of myofibroblasts. All 41 specimens of club foot stained positively for vimentin as against only one of the 12 control specimens. By contrast, there was no difference in staining for desmin or alpha-smooth muscle actin. EM showed some variability in the appearance of ligamentous cells. Most contained bundles of microfilaments in the cytoplasm and many had abundant pinocytotic vesicles, but no basal lamina or plasmalemmal attachment plaques. Cells of the medial ligamentous tissue in patients with club foot contain vimentin and others have myofibroblastic characteristics. Both features may contribute to recurrence after soft-tissue release.

Structural disorders at the insertion of the supraspinatus tendon. Relation to tensile strength.

We examined macroscopically and microscopically 55 cadaver rotator-cuff tendons attached to their humeral heads to determine the distance between the edge of the articular cartilage and the tendon insertion of the supraspinatus (the width of the sulcus) and the score of regressive changes at the sulcus. In 33 specimens we measured the tensile strength. The width of the sulcus was correlated with the score of regressive changes and with the ultimate tensile strength of the supraspinatus tendon. The width of the sulcus correlated positively with the score of regressive changes (r = 0.66, p < 0.0001), but there was a negative correlation between the latter and the ultimate tensile strength (r = -0.81, p = 0.001) and between the width of the sulcus and the ultimate tensile strength (r = -0.74, p = 0.004). We believe that the width of the sulcus is a simple and useful clinical indicator of the integrity and the tensile strength of the supraspinatus tendon.

"Bursal reactions" in rotator cuff tearing, the impingement syndrome, and calcifying tendinitis.

Subacromial bursal specimens from 63 patients undergoing surgery for rotator cuff tearing (n = 43), the impingement syndrome (n = 14), and calcifying tendinitis n = 6) were studied to characterize the reactions that develop at the tendinopathy "lesional" sites. Intensity of the bursal reactions and production of type III collagen vary considerably, with the highest incidence of both seen in patients with rotator cuff tears. The intensity of bursal reactions correlated with the degree of formation of perivascular new collagen and type III collagen expression. In 22 of the 63 patients the bursal reaction distant to the tendon lesion was also studied. It was minimal and did not correlate to the lesional bursal findings. A strong correlation, however, existed between surgical appearance and histologic grading. The term "localized bursal reaction" as opposed to bursitis more correctly describes bursal involvement. Resection of bursal tissues should be limited to the lesional tissue that interferes with subacromial motion.

Recent advances in shoulder surgery.

Major changes have taken place in the diagnosis and treatment of rotator cuff tears. It seems that magnetic resonance imaging alone as a diagnostic tool is still not sensitive enough, particularly in the diagnosis of partial tears. Arthrography and arthroscopy are still considered essential for an accurate preoperative diagnosis. To guarantee a better postoperative result, a carefully planned course of preoperative physiotherapy is mandatory. In experienced hands, arthroscopic surgery gives results comparable to those obtained with open procedures. A careful debridement, anterior acromioplasty, and decompression have replaced extensive surgical intervention in the treatment of massive tears. The first results in treating calcifying tendinitis with shock-wave therapy seem encouraging. A more refined diagnosis of the impingement syndrome is a prerequisite for a successful outcome because impingement is not caused by a narrowing of the subacromial space in all patients. Increase in contents of this space and instability are equally important factors.

Histologic analysis of fetal ulnar variance.

Twenty-eight fetal wrists aged 5 to 21 weeks gestation were examined histologically to assess ulnar variance. There was a trend from ulna negative to ulna neutral among this population. Of 10 wrists in group I (5-8 weeks gestation), 8 were ulna negative and 2 were ulna neutral. Of nine wrists in group II (11-13 weeks gestation), three were ulna negative and six were ulna neutral. Of nine wrists in group III (18-21 weeks gestation), two were ulna negative and seven were ulna neutral. Overall, 13 embryos demonstrated an ulna negative variance; the remainder had ulna neutral variance. These results are significantly different than the incidence of ulnar variance in adults. With growth, factors must occur that change this fetal relationship of radius to ulna.

Calcifying tendinitis.

Calcifying tendinitis is not due to a dystrophic calcification of the degenerative tendinous tissue but due to a cell mediated reactive process. In fact, following formation of a deposit resorption usually ensues which in turn will be followed by a tendon reconstitution. If patent conservative measures fail, surgery should only be contemplated in the presence of radiologically dense, homogenous and well delineated deposits which indicate that the resorptive activity has not set in. If, on the other hand, there is evidence of ongoing resorption the decision for surgery should be postponed since only exceptionally natural resorption will not occur.

The collagen types in the attachment zone of rotator cuff tendons in the elderly: an immunohistochemical study.

OBJECTIVE: The attachment zone of the rotator cuff tendons in the elderly was studied immunohistochemically in order to determine how degenerative changes affected the pattern of collagen fiber distribution. METHODS: Twenty-seven cuffs with their bony insertion were obtained from 22 postmortem cases of both sexes ranging in age from 52 to 90 years and without a history of shoulder ailments. In addition, 3 cuff specimens from cadavers in the 3rd and 4th decades were examined for comparison. Sections of formalin fixed tissues were stained by peroxidase antiperoxidase (PAP) technique using monoclonal antibodies against types I, II and III collagen. RESULTS: Degenerative changes affecting the fibrocartilage primarily were characterized by calcification, fibrovascular proliferation and microtears. In addition, they were found in all the cuff tendons of elderly individuals but not in those from younger subjects. Immunohistochemically, the attachment zone in areas without degenerative lesions showed collagen type I labelling strongly in bone but only moderately in the fibrocartilage. The predominant labelling in the fibrocartilage was for collagen type II, and collagen type III labelled principally in perichondrocytic areas. The tide-mark showed inconsistent labelling for any of the collagen types. In the presence of degenerative lesions, the disposition of fiber types was interrupted by calcification and microtears. Collagen type II composition of the fibrocartilage was markedly altered by the presence of fibrovascular tissue which labelled only for collagen type III. CONCLUSION: We conclude that severe degenerative changes in the cuff tendons of elderly individuals, alter the collagen characteristic of the rotator cuff and that the changes could be associated with impairment of biomechanical properties of the attachment zone, and may give rise to the clinical syndrome of enthesopathy.

Cortical porosis under plates. Reaction to unloading or to necrosis?

Cortical porosis under plates used for the fixation of fractures is often attributed to the interference of the plates with cortical perfusion, resulting in necrosis, which in turn induces remodeling. To our knowledge, no histomorphometric studies have been published that demonstrate the correlation between cortical necrosis and porosis. The objective of this study was to test the hypothesis that cortical necrosis is related to changes associated with porosis. Standard and railed plates were applied to intact femora in ten dogs. Histomorphometric studies done at eight and twenty-four weeks after insertion of the plate failed to show a significant positive correlation between necrosis and porosis irrespective of the type of plate used. Porosis was always greater in the inner cortical sector, where no increased necrosis was noted, than in the outer cortical sector, where necrosis was present.

The pathogenesis of club foot. A histomorphometric and immunohistochemical study of fetuses.

We studied 16 club feet and 27 normal feet from spontaneously aborted human fetuses in the second trimester of gestation and measured the length of the spring ligament, and the declination angle and size of the talus. We also studied the cellular characteristics of the spring ligament and the immunohistochemical features of the medial ankle ligaments using monoclonal antibodies against type-III collagen, desmin, vimentin, and smooth muscle actin. Histomorphometric results indicated that the talar deformity was not the primary lesion. Histological and immunohistochemical findings showed that the cells and collagen fibres of the medial ankle ligaments of club feet appeared to be the site of the earliest changes, in that they had lost their spatial orientation and had contracted. In severe club feet before the third trimester of gestation, myofibroblast-like cells seemed to create a disorder of the ligaments resembling fibromatosis. This led to contraction and resulted in typical club-foot deformity.

Prenatal development of the iliolumbar ligament.

Serial sections, in the frontal plane, of 12 human fetuses showed that the iliolumbar ligament was always present at the gestational age of 11 to 15 weeks; in younger specimens, it could not be identified. The ligament develops during the prenatal period and is not formed by metaplasia of the quadratus lumborum muscle during the second decade of life.

Refractures: a consequence of impaired local bone viability.

Bone necrosis secondary to avascularity may not only delay or inhibit consolidation of a fracture, it may also be a cause of refracture. Both initial trauma und surgical insult will determine the extent of necrosis. Only the latter is under the surgeon's control; it can be reduced by gentle soft tissue handling and by minimizing periosteal stripping. While the impact of avascular necrosis on fracture healing is well recognized, its role in the pathogenesis of refractures has received less attention. Cortical necrosis delays bridging of gaps; these gaps act as stress risers which, following resumption of full activity or after implant removal, can lead to refracture. Evaluation of 28 refractures in 25 patients, with biopsies in 14 patients, suggests that the duration of fracture immobilization through external or internal means must be sufficiently long to allow vascular invasion of necrotic areas, their substitution by new bone and bridging of the fracture. These processes must be followed by radiographic studies prior to implant removal. Special attention needs to be paid to adequate visualization of the fracture gap on successive radiographs.

Collagen type III in rotator cuff tears: An immunohistochemical study.

The presence and distribution of collagen type III, which represents newly formed fibers of early repair, were investigated in four surgically removed en bloc specimens of complete rotator cuff tears. The patients were two men and two women who ranged in age from 63 to 71 years. They had received preoperative, conservative treatment for a period varying from 3 months to 3 years. For the identification of the collagen immunohistochemical staining was performed by the peroxidase-antiperoxidase method with the use of monoclonal antibody against human collagen type III. Collagen type III was discernible throughout the tendon proper in all specimens. It often occurred in association with proliferating fibroblastic cells. Collagen type III was abundant only in the perivascular spaces of the much thickened bursal wall that extended over the margins of the tear. We concluded that the presence of collagen type III indicates the need for a continued attempt for repair at the site of the tear, including both bursal and tendinous tissues.