Fibrous cartilage in the rotator cuff: A pathogenetic mechanism of tendon tear?

Exploring the role of intratendinous pressure in the pathogenesis of tendon pathology: a narrative review and conceptual framework

Despite the high prevalence of tendon pathology in athletes, the underlying pathogenesis is still poorly understood. Various aetiological theories have been presented and rejected in the past, but the tendon cell response model still holds true. This model describes how the tendon cell is the key regulator of the extracellular matrix and how pathology is induced by a failed adaptation to a disturbance of tissue homeostasis. Such failure has been attributed to various kinds of stressors (eg, mechanical, thermal and ischaemic), but crucial elements seem to be missing to fully understand the pathogenesis. Importantly, a disturbance of tissue pressure homeostasis has not yet been considered a possible factor, despite it being associated with numerous pathologies. Therefore, we conducted an extensive narrative literature review on the possible role of intratendinous pressure in the pathogenesis of tendon pathology. This review explores the current understanding of pressure dynamics and the role of tissue pressure in the pathogenesis of other disorders with structural similarities to tendons. By bridging these insights with known structural changes that occur in tendon pathology, a conceptual model was constituted. This model provides an overview of the possible mechanism of how an increase in intratendinous pressure might be involved in the development and progression of tendon pathology and contribute to tendon pain. In addition, some therapies that could reduce intratendinous pressure and accelerate tendon healing are proposed. Further experimental research is encouraged to investigate our hypotheses and to initiate debate on the relevance of intratendinous pressure in tendon pathology.

Suture anchor reinsertions of distal biceps rupture: a histologic analysis of a torn tendon and clinical results at short- and long-term follow-up

BACKGROUND

Distal biceps brachii tendon (DBBT) rupture is a relatively rare injury. Nonsurgical treatment determines 30%-40% power loss of elbow flexion and up to 50% of forearm supination. Therefore, refixation of the DBBT is recommended. The DBBT is exposed to tension and compression loading. It is known that the tendon under compression might develop fibrocartilaginous metaplasia that improves the resistance to compression but reduces the resistance to tension. To test this hypothesis, the present study evaluated the presence of cartilage in DBBT samples. Furthermore, the present study evaluated the clinical and functional outcomes of anatomic reinsertion through suture anchors in a cohort of patients after 1, 3, and 5 years of follow-up.

METHODS

Between 2011 and 2014, 21 patients with DBBT tear underwent a suture anchor reattachment. Histochemical and immunohistochemical analysis of torn samples of DBBT collected at the time of surgical repair were performed to test the presence of cartilage. During the follow-up examination, mobility, elbow radiographs, Mayo Elbow Performance Score, and isokinetic analysis were prospectively evaluated.

RESULTS

Fibrocartilage was detected in all tendon samples collected. Two cases of transient paresthesia in the lateral antebrachial cutaneous nerve occurred, but they resolved in 6 weeks. There were no vascular deficits, re-ruptures, radioulnar synostoses, or infective complications at follow-up. Three patients reported loss of supination. Mayo Elbow Performance Score showed good and excellent clinical and functional results. No significant differences about strength and fatigue in flexion-supination were recorded between the surgical and contralateral side at 3 and 5 years of follow-up. Arm dominance influenced supination but not flexion.

CONCLUSION

On the basis of our results, we find that the presence of cartilage metaplasia might make the DBBT at higher risk of rupture assuming the compression loading and the hypovascular zone of the tendon. However, concerning the lack of histologic analysis of the healthy DBBT, its role in tendon pathology remains to be clearly defined. The technique of suture anchor reinsertion by a single incision was shown to be safe, with few complications and good functional results at 5 years of follow-up. No significant differences were reported between the injured and noninjured side in terms of flexion and supination isokinetic analysis, whereas arm dominance had a positive effect on supination.

Arthroscopic Transosseous Repair of Rotator Cuff Tear and Greater Tuberosity Cysts

Purpose

To evaluate the short-term outcomes of rotator cuff repair in the presence of a greater tuberosity cyst (GTC) using a transosseous repair technique.

Methods

This study included patients who underwent arthroscopic rotator cuff tear repair with a transosseous technique and were evaluated clinically and by postoperative magnetic resonance imaging (MRI) after 1 year. The inclusion criteria were based on the results of preoperative MRI and were as follows: patients identified as having a repairable full-thickness rotator cuff tear associated with the presence of cystic changes at the tendon insertion site of the greater tuberosity, defined as a GTC involving the footprint area of the torn tendon (supraspinatus and/or infraspinatus tendons).

Results

We evaluated 25 patients. The mean preoperative and postoperative American Shoulder and Elbow Surgeons scores were 39.48 (P = .530) and 84.64 (P = .035), respectively; Constant shoulder scores, 38.96 (P < .005) and 80.28 (P = .425), respectively; and University of California–Los Angeles shoulder rating scale scores, 10.6 (P = .045) and 29.04 (P = .315), respectively. The GTC mapping system was easily adopted in all the MRI examinations independently from the quality of the images. The GTCs were mostly located in the superficial anterolateral section of the humeral head and in both the posterolateral sections (superficial and deep).

Conclusions

Arthroscopic transosseous rotator cuff repair led to significant mid-term improvement and satisfactory subjective outcomes with low complication and failure rates in this study. The GTC mapping system could be useful to evaluate GTCs and to aid surgeons in the choice of the best surgical technique.

Level of Evidence

Level IV, therapeutic case series.

Macroscopic and microscopic anatomy of the rotator cable in the shoulder

BACKGROUND

The rotator cable, a semicircular fiber bundle in the lateral portion of the rotator cuff, has been believed to transmit forces among cuff tendons. This study was performed to clarify the functional anatomy of the rotator cable through histoanatomical methods.

METHODS

Twenty-two cuff-intact shoulders of fixed cadavers were dissected. The cable was investigated from the cuff surface and articular/bursal sides of the capsule. The width of the cable and distances from the capsule attachment to both of the lateral and medial borders of the cable were measured, and their correlations to the humeral head diameter were calculated. The location of the cable on the humeral head was observed and recorded. In additional five shoulders the cuff/capsule complex and greater tubercle were harvested en block and histologically investigated.

RESULTS

The rotator cable was evident in the capsule of 14 shoulders. One specimen demonstrated the cable of double curves. The capsule thickness alteration corresponding to the medial border of the cable with a single curve existed approximately on the so-called 'flexion point' where the humerus started to form a spherical curve from the greater tubercle to the joint surface. The 'flexion point' macroscopically corresponded to the medial boundary of the contact area between the cuff and head. The distance between the cable and capsule attachment showed marked negative correlation to the head diameter. Histologically the cable demonstrated cartilaginous metaplasia and vertical fiber orientation to the supraspinatus.

CONCLUSIONS

The rotator cable does not always exist in all the shoulders and its appearances are varied. The location and cartilaginous metaplasia of the cable suggested compression force between the cuff and humeral head, and the force would help cable creation in capsule layer. The vertical fiber orientation of the cable to the supraspinatus would be unlikely to explain force transmission among the cuff tendons.

Ex vivo evaluation of an alternative technique for resection of the proximal manica flexoria in horses

OBJECTIVE

To describe and evaluate an alternative technique for tenoscopic resection of the manica flexoria (MF).

STUDY DESIGN

Descriptive study.

SAMPLE POPULATION

Equine cadaver forelimbs and hind limbs (n = 36).

METHODS

Three surgeons varying in experience resected the MF in 12 limbs. The procedure was divided into six steps, including resection of the lateral/medial borders of the MF with a hook knife and resection of the proximal border with a micro scalpel. Outcomes compared between surgeons included completeness of resection, appearance of the margins of resection, appearance of the resected MF, collateral damage, and time required for resection.

RESULTS

The MF was successfully resected in all specimens, with a median time of 14 minutes 54 seconds (range, 6 minutes 42 seconds to 43 minutes 33 seconds). Nineteen of 36 MF were categorized as symmetric, 11 of 36 MF were categorized as mildly asymmetrical, and six of 36 MF had unequal borders. No differences were detected between surgeons regarding the appearance of the MF and number of iatrogenic lesions. Five lesions were considered potentially clinically relevant; three were caused by the arthroscope in the scutum (1) and the deep digital flexor tendon (DDFT; 2), and two consisted of DDFT damage caused by the microscalpel.

CONCLUSION

The MF was successfully and symmetrically resected with minimal damage to adjacent structures by surgeons with varying levels of experience.

CLINICAL SIGNIFICANCE

The results of this study provide evidence to justify further evaluation of the technique described here in live horses with rupture of the MF.

Immunohistochemical features of rotator cuff tendinopathy

BACKGROUND

Rotator cuff tendinopathy is a common musculoskeletal ailment in sedentary and athletic individuals. Various mediators of inflammation have been detected in human tendons: they are thought to initiate or progress the course of tendinopathy.

SOURCES OF DATA

An online search was conducted using AMED, CINAHL, Embase, The Cochrane Library, PEDro and Pubmed, using the terms tendinopathy, tendon, tendinitis, tendinosis, histology, histopathology, immunohistochemistry, immunohistochemical, rotator cuff and pain.

AREAS OF AGREEMENT

Histological examination of tendinopathic tendons shows degeneration of the collagen structure and infiltration of fat and vessels, together with increased expression of inflammatory cytokines, MMP-1, 2, 3, 9, 13, vascular endothelial growth factor and Hypoxia inducible factor (HIF).

AREAS OF CONTROVERSY

Most of the studies about this topic exhibited limited validity because of lack of appropriately matched controls and no inclusion or exclusion criteria. The evidence associated with the histopathological analysis of the rotator cuff is limited.

GROWING POINTS

The histochemical and immunohistochemical features of rotator cuff tendinopathy are still unclear. A thorough understanding of the vascularity, innervation and biochemical mediators of pain could be used to target rotator cuff pathology, and possibly guide the therapy of painful rotator cuff disorders.

AREAS TIMELY FOR DEVELOPING RESEARCH

There is a need for a validated reproducible method of rotator cuff tendon biopsy evaluation. We require further studies with improved designs to effectively evaluate the histological and immunohistochemical features of rotator cuff tendinopathy.

A Systematic Summary of Systematic Reviews on the Topic of the Rotator Cuff

BACKGROUND

The number of systematic reviews and meta-analyses published on the rotator cuff (RC) has increased markedly.

PURPOSE

To quantify the number of systematic reviews and meta-analyses published on the RC and to provide a qualitative summary of the literature.

STUDY DESIGN

Systematic review; Level of evidence, 4.

METHODS

A systematic search for all systematic reviews and meta-analyses pertaining to the RC published between January 2007 and September 2017 was performed with PubMed, MEDLINE, and the Cochrane Database of Systematic Reviews. Narrative reviews and non-English language articles were excluded.

RESULTS

A total of 1078 articles were found, of which 196 met the inclusion criteria. Included articles were summarized and divided into 15 topics: anatomy and function, histology and genetics, diagnosis, epidemiology, athletes, nonoperative versus operative treatment, surgical repair methods, concomitant conditions and surgical procedures, RC tears after total shoulder arthroplasty, biological augmentation, postoperative rehabilitation, outcomes and complications, patient-reported outcome measures, cost-effectiveness of RC repair, and quality of randomized controlled trials.

CONCLUSION

A qualitative summary of the systematic reviews and meta-analyses published on the RC can provide surgeons with a single source of the most current literature.

Fibrocartilaginous metaplasia identified in the long head of the biceps brachii

BACKGROUND

In the glenohumeral joint, the long head of biceps brachii (LHBB) is exposed to tension and compression loading. The short head of biceps brachii (SHBB) works only in tension. It is known that tendon under compression might develop fibrocartilaginous metaplasia that improves the resistance to compression but reduces the resistance to tension. This study evaluated the presence of cartilage in LHBB and SHBB samples, supporting its possible role in tendon tear.

METHODS

Between 2014 and 2016, 13 samples of LHBB and SHBB were collected during surgery for shoulder instability, glenohumeral arthritis, and massive rotator cuff tears. The samples were stained with hematoxylin and eosin, safranin-O, and Alcian blue (pH 1.0) for light microscopy. Immunohistochemistry was performed using anti-S100, anti-collagen I and II, and anti-tenascin-C antibodies.

RESULTS

Histochemistry: LHBB samples showed matrix disorganization, with clusters of chondrocyte surrounded by collagen fibers and glycosaminoglycans. Safranin-O showed evident metachromasia. SHBB samples did not show any matrix disorganization or cartilaginous metaplasia. Immunohistochemistry: In all LHBB samples, anti-S100 and anti-collagen II showed cartilage in proximity of the tendon tear. Tenascin C immunostained closely to the disorganized matrix areas. SHBB, however, showed no positive areas for S-100, anti-collagen II, or tenascin C.

CONCLUSIONS

According to our results, we hypothesize that the repeated stimulation in compression may induce the formation of fibrous cartilage. However, to date its role in tendon pathology remains to be clearly defined.

An anatomical and histological study of the equine proximal manica flexoria

Objectives: The main aim was to describe the gross and histological appearance of the equine manica flexoria and to identify any differences between the forelimbs and hind-limbs. An additional aim was to relate the findings to diagnostic and surgical anatomy of the manica flexoria.

Methods: Measurements of the manica flex-oria were made on cadaveric limbs from horses free from pathology within the digital flexor tendon sheath. Histological sections, stained with haematoxylin and eosin and alcian- periodic acid schiff, were evaluated based on three micro-anatomical zones from dorsal to palmar or plantar. The prevalent tenocyte morphology, number, and distribution of blood vessels and nerves were described in each zone. Forelimb and hindlimb measurements were compared using a Students T-test.

Results: Proximally, the manica flexoria attaches to the digital flexor tendon sheath via a reflection of areolar tissue. The fibrous manica flexoria is longer in the forelimb (32.0 ± 4.2 mm) than the hindlimb (29.4 ± 3.8 mm) (p = 0.04), with the areolar portion longer in the hindlimb (22.9 ± 5.3 mm) compared to the forelimb (16.7 ± 4.3 mm) limb (p = 0.0005). Histologically, degenerate blood vessels were prevalent in the palmar/ plantar regions and were associated with chondrocyte-like tenocytes, indicative of fibrocartilagenous metaplasia.

Clinical significance: The study has provided a detailed anatomical description of the manica flexoria relevant for interpretation of diagnostic and surgical evaluation. Fibrocartilaginous metaplasia occurs on the palmar/plantar surfaces of the manica flex-oria.

The Degeneration of Meniscus Roots Is Accompanied by Fibrocartilage Formation, Which May Precede Meniscus Root Tears in Osteoarthritic Knees

BACKGROUND

Fibrocartilage metaplasia in tendons and ligaments is an adaptation to compression as well as a pathological feature during degeneration. Medial meniscus posterior roots are unique ligaments that resist multidirectional forces, including compression.

PURPOSE

To characterize the degeneration of medial meniscus posterior root tears in osteoarthritic knees, with an emphasis on fibrocartilage and calcification.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

Samples of medial meniscus posterior roots were harvested from cadaveric specimens and patients during knee replacement surgery and grouped as follows: normal reference, no tear, partial tear, and complete tear. Degeneration was analyzed with histology, immunohistochemistry, and real-time polymerase chain reaction. Uniaxial tensile tests were performed on specimens with and without fibrocartilage. Quantifiable data were statistically analyzed by the Kruskal-Wallis test with the Dunn comparison test.

RESULTS

Thirty, 28, and 42 samples harvested from 99 patients were allocated into the no tear, partial tear, and complete tear groups, respectively. Mean modified Bonar tendinopathy scores for each group were 3.97, 9.31, and 14.15, respectively, showing a higher degree of degeneration associated with the extent of the tear (P < .05 for all groups). The characterization of root matrices revealed an increase in fibrocartilage according to the extent of the tear. Tear margins revealed fibrocartilage in 59.3% of partial tear samples and 76.2% of complete tear samples, with a distinctive cleavage-like shape. Root tears with a similar shape were induced within fibrocartilaginous areas during uniaxial tensile testing. Even in the no tear group, 56.7% of samples showed fibrocartilage in the anterior margin of the root, adjacent to the meniscus. An increased stained area of calcification and expression of the ectonucleotide pyrophosphatase/phosphodiesterase 1 gene were observed in the complete tear group compared with the no tear group (P < .0001 and P = .24, respectively).

CONCLUSION

Fibrocartilage and calcification increased in medial meniscus posterior roots, associated with the degree of the tear. Both findings, which impair the ligament's resistance to tension, may play a pivotal role during the pathogenesis of degenerative meniscus root tears in osteoarthritic knees. Fibrocartilage and calcification may be useful as diagnostic markers as well as markers of degeneration, which may aid in determining the treatment modality in meniscus root tears. The presence of fibrocartilage in intact roots may suggest an impending tear in osteoarthritic knees.

Do low field magnetic resonance imaging abnormalities correlate with macroscopical and histological changes within the equine deep digital flexor tendon?

Correlating magnetic resonance (MR) imaging and histopathological findings is essential to validate low field MR imaging in lame horses. This study aimed to compare signal changes in the deep digital flexor tendon (DDFT) of the distal limb on low field MR imaging with macroscopical and histological findings. Cadaver limbs from lame horses with DDFT lesions were selected. The DDFT MR imaging findings and histopathological results were graded, and macroscopical abnormalities were recorded. There was a strong correlation between MR imaging and histopathology grades (rs = 0.76, p < 0.001) in the foot. There was moderate agreement (Kappa statistic 0.52) between the MR and histopathology grades; agreement was superior further proximal in the foot. The presence and severity of pathology in the DDFT are well represented by the presence and severity of MR imaging signal changes. The study supports the use of low field MR imaging for diagnosis of equine distal limb DDFT lesions.

Anatomic and histologic features and ultrasonographic appearance of the collateral ligaments of the metacarpophalangeal and metatarsophalangeal joints in cadaveric limbs from horses without lameness

OBJECTIVE

To describe the anatomic and histologic features of the collateral ligaments (CLs) of the metacarpophalangeal (MCP) and metatarsophalangeal (MTP) joints in cadaveric limbs obtained from nonlame horses and to compare the histologic findings with the ultrasonographic appearance of the CLs.

SAMPLE

Medial and lateral CLs of the MCP and MTP joints of 28 limbs (16 forelimbs and 12 hind limbs) from 9 adult nonlame horses euthanized for reasons unrelated to the study.

PROCEDURES

26 limbs of 8 horses were examined by ultrasonography immediately after euthanasia. Postmortem gross and histologic examinations were performed for all 28 limbs. Histologic and ultrasonographic images were graded and compared.

RESULTS

Ultrasonographically, the mean ± SD depth and width of the superficial CL were 5.1 ± 0.7 mm and 20.5 ± 1.7 mm, respectively. On histologic examination, only 125 of 319 (39%) specimens obtained from 56 medial and lateral CLs appeared normal. Histopathologic findings varied from mild changes in cellular density and collagen fiber orientation to severe fibrocartilaginous metaplasia. The degree of CL lesion severity increased distally, and the lateral CL was affected more frequently than was the medial CL. Ultrasonographically detectable abnormalities were not correlated with the histologic findings.

CONCLUSIONS AND CLINICAL RELEVANCE

In horses, histologic abnormalities within the CLs of the MCP and MTP joints may be an adaptive response to joint hyperextension and compression and might predispose horses to desmopathy and ligament failure in the event of trauma. Ultrasonography did not detect morphologic changes of the CL matrix. For an accurate diagnosis of subclinical lesions, more sensitive imaging techniques (eg, MRI) should be considered.

Purified collagen I oriented membrane for tendon repair: an ex vivo morphological study

Injured tendons have limited repair ability after full-thickness lesions. Tendon regeneration properties and adverse reactions were assessed ex vivo in an experimental animal model using a new collagen I membrane. The multilamellar membrane obtained from purified equine Achilles tendon is characterized by oriented collagen I fibers and has been shown to sustain cell growth and orientation in vitro. The central third of the patellar tendon (PT) of 10 New Zealand White rabbits was sectioned and grafted with the collagen membrane; the contralateral PT was cut longitudinally (sham-operated controls). Animals were euthanized 1 or 6 months after surgery, and tendons were subjected to histological and Synchrotron Radiation-based Computed Microtomography (SRµCT) examination and 3D structure analysis. Histological and SRµCT findings showed satisfactory graft integration with native tendon. Histological examination also showed ongoing angiogenesis. Adverse side-effects (inflammation, rejection, calcification) were not observed. The multilamellar collagen I membrane can be considered as an effective tool for tendon defect repair and tendon augmentation.

A systematic review of the histological and molecular changes in rotator cuff disease

INTRODUCTION

The pathogenesis of rotator cuff disease (RCD) is complex and not fully understood. This systematic review set out to summarise the histological and molecular changes that occur throughout the spectrum of RCD.

METHODS

We conducted a systematic review of the scientific literature with specific inclusion and exclusion criteria.

RESULTS

A total of 101 studies met the inclusion criteria: 92 studies used human subjects exclusively, seven used animal overuse models, and the remaining two studies involved both humans and an animal overuse model. A total of 58 studies analysed supraspinatus tendon exclusively, 16 analysed subacromial bursal tissue exclusively, while the other studies analysed other tissue or varying combinations of tissue types including joint fluid and muscle. The molecular biomarkers that were altered in RCD included matrix substances, growth factors, enzymes and other proteins including certain neuropeptides.

CONCLUSIONS

The pathogenesis of RCD is being slowly unravelled as a result of the significant recent advances in molecular medicine. Future research aimed at further unlocking these key molecular processes will be pivotal in developing new surgical interventions both in terms of the diagnosis and treatment of RCD.

Histopathology of rotator cuff tears

The pathogenesis of rotator cuff tears is multifactorial. Tendon abnormalities of the rotator cuff include alteration of collagen fiber structure, tenocytes, cellularity, and vascularity. Ruptured tendons show marked collagen degeneration and disordered arrangement of collagen fibers. Fibroblast population decreases as the size of the tear in the rotator cuff increases. The larger fibroblast population seen in the smaller tears is also actively proliferating and is part of an active reparative process. Inflammatory cell infiltrate correlates inversely to rotator cuff tear size in the torn supraspinatus tendon samples, with larger tears showing a marked reduction in all cell types. As tear size increase, there is also a progressive decrease in the number of blood vessels. Whether rotator cuff tear heals spontaneously is an important pathologic and clinical question. Histologic changes indicative of repair and inflammation lead to consider biological options in addition to biomechanical treatment of the rotator cuff tears.

Rotator cuff re-tear or non-healing: histopathological aspects and predictive factors

PURPOSE

The aim of the study was to evaluate the histopathological changes that occur in the tendon and subacromial bursal tissue in patients with rotator cuff tear trying to correlate these changes to their healing capability.

METHODS

Eighty-four patients were clinically evaluated with the Constant Scale. Radiographs and MRI were performed preoperatively and ultrasound were performed postoperatively. For each patient, a biopsy of the supraspinatus tendon and subacromial bursa was performed, and the specimens were histopathologically analyzed.

RESULTS

Tendons histopathological features consisted of loss of structural organization, poor or absent neoangiogenesis, chondral metaplasia, and fibrosis. Bursal features consisted of neoangiogenesis, absence of chondral metaplasia, hyperplasia/hypertrophy, and absence of necrosis. Direct correlation was seen between tendon and bursal hyperplasia and time of the onset of symptoms; between tendon chondral metaplasia, fibrosis, bursal neoangiogenesis, inflammation, and patient age; between tendon neoangiogenesis, hyperplasia, necrosis, fibrosis, bursal necrosis, inflammation, and lesion size; on the contrary, tendon fibrosis, necrosis, and bursal tissue inflammation decrease as time passes from the onset of symptoms. Tendon fibers disarray, neoangiogenesis, and inflammation decreases as the patient's age increases. Bursal tissue fibrosis decreases as lesion size increases.

CONCLUSIONS

Simple histopathological techniques should be employed routinely to assess the tissue quality, with the aim to predict future clinical evolution (repair or non-repair). Comparing the histopathological data with the demographical information and the descriptive statistics, it is possible to define the RCT repair at risk and identify which RCT will be able to heal.

Are matrix and vascular changes involved in the pathogenesis of deep digital flexor tendon injury in the horse?

It was hypothesised that there is increased blood vessel frequency and proteoglycan staining intensity within the distal aspect of the deep digital flexor tendon (DDFT) in horses with chronic foot pain. Samples of the DDFT from three standardised sites from 10 age-matched mature horses, with chronic foot pain (Group L) or with no history of forelimb lameness (Group N), were collected for this study. A histological analysis of haematoxylin and eosin-stained sections focussed on the frequency and location of blood vessels, while safranin 0 fast green staining was used for semi-quantitative assessment of matrix proteoglycan. The frequency and immunoreactivity of endothelial cell-labelled blood vessels were determined using factor VIII immunolocalisation. There was increased frequency of blood vessels (P=0.048) and increased proteoglycan staining intensity (P=0.028) in Group L, compared with Group N. Qualitative micro-anatomical differences in the matrix and tenocytes were noted between Groups N and L. There was reduced factor VIII staining within the vasculature of horses from Group L, compared with Group N. The results suggested that chronic foot pain may be associated with altered DDFT matrix composition, which could be a potential indicator of degenerative change. The increased vascularity may represent a reparative response to a degenerative tendonopathy.

Rupture of the distal biceps brachii tendon: conservative treatment versus anatomic reinsertion--clinical and radiological evaluation after 2 years

INTRODUCTION

Distal biceps tendon rupture is a relatively rare injury. It commonly occurs in the dominant extremity of middle-aged men during an excessive eccentric tension as the arm is forced from a flexed position, while it is rarely observed during sport activities. Many techniques, including non-operative and surgical option, have been described for the treatment of a ruptured distal biceps tendon, but there is still considerable controversy about the management of choice.

MATERIAL AND METHODS

Nine patients affected with traumatic distal tendon ruptures of the biceps brachii were followed-up for a minimum of 24 months. Five patients underwent surgery (two-incision technique) and four patients were treated conservatively. Tendon readaptation to its origin was done by a suture metal anchor. Outcome was evaluated based on the physical examination, radiographic analysis and the SECEC elbow score.

RESULTS

The SECEC elbow score results show that every single item result is in favour of surgical treatment. On measurements of motion, we found a slight flexion-extension deficit in two patients, but reduced supination in six patients and reduced pronation in four. Two patients had postoperative dysfunction of the deep branch of the radial nerve. Radiographic examination showed heterotopic bone formation on the radial tuberosity around the presumed insertion of the reattached tendon in 2 of 5 patients and ectopic ossification more proximally in the area of the biceps muscle

CONCLUSION

Our findings confirm the view that anatomic repair of distal biceps tendon rupture provides consistently good results and early anatomic reconstruction can restore strength and endurance for the elbow.

Supraspinatus tendon composition remains altered long after tendon detachment

Most rotator cuff surgery is performed on chronic tears, but changes in the composition of chronically torn tendons remain poorly understood. In this study we surgically created supraspinatus tears in the rat and analyzed the composition of the tendon over time using immunohistochemistry. We found that collagen types I and XII were greatly increased initially after injury and then decreased with time. Collagen type III was detected and persisted in the scar for months. Decorin and biglycan were increased initially and then decreased, although decorin remained elevated from normal for months after injury. Aggrecan and collagen type II were detected in small amounts after detachment, which was associated with the expression of sulfated glycosaminoglycans. These alterations were similar to those seen in human studies. As the quality of the tendon is an important factor in repair, these findings may partially explain why chronic tears heal differently than acute tears.