The Effects of Polysulphated Glycosaminoglycan on the Healing of Collagenase Induced Tendinitis

Evaluation of experimentally induced injury to the superficial digital flexor tendon in horses by use of low-field magnetic resonance imaging and ultrasonography

OBJECTIVE

To evaluate tendon injuries in horses over a 16-week period by use of ultrasonography and low-field magnetic resonance imaging (MRI).

SAMPLE

Tendons of 8 young adult horses.

PROCEDURES

The percentage of experimentally induced tendon injury was evaluated in cross section at the maximal area of injury by use of ultrasonography and MRI at 3, 4, 6, 8, and 16 weeks after collagenase injection. The MRI signal intensities and histologic characteristics of each tendon were determined at the same time points.

RESULTS

At 4 weeks after collagenase injection, the area of maximal injury assessed on cross section was similar between ultrasonography and MRI. In lesions of > 4 weeks' duration, ultrasonography underestimated the area of maximal cross-sectional injury by approximately 18%, compared with results for MRI. Signal intensity of lesions on T1-weighted images was the most hyperintense of all the sequences, lesions on short tau inversion recovery images were slightly less hyperintense, and T2-weighted images were the most hypointense. Signal intensity of tendon lesions was significantly higher than the signal intensity for the unaltered deep digital flexor tendon. Histologically, there was a decrease in proteoglycan content, an increase in collagen content, and minimal change in fiber alignment during the 16 weeks of the study.

CONCLUSIONS AND CLINICAL RELEVANCE

Ultrasonography may underestimate the extent of tendon damage in tendons with long-term injury. Low-field MRI provided a more sensitive technique for evaluation of tendon injury and should be considered in horses with tendinitis of > 4 weeks' duration.

Plasma rico em plaquetas no tratamento de tendinite induzida em eqüinos: avaliação ultra-sonográfica

O objetivo deste trabalho foi estudar o efeito do plasma rico em plaquetas (PRP) no tratamento da tendinite induzida no tendão do músculo flexor digital superficial (TFDS) de eqüinos mediante avaliação ultra-sonográfica. Para isso foram utilizados seis eqüinos hígidos machos castrados, com idade de 8-15 anos (x=12 anos). A tendinite do TFDS foi provocada em ambos os membros torácicos, mediante a administração intratendínea de 2,5mg de colagenase (2,5mg.µL-1), sendo esse procedimento considerado o início da fase experimental. Doze dias após a indução da tendinite, os animais foram submetidos a dois tratamentos: sendo que na lesão efetuada no TFDS direito (grupo tratado, GT), foram administrados 2,5mL de PRP ativado com cloreto de cálcio a 0,0125mol.L-1, contendo concentrações variando de 320.000 a 500.000 plaquetas.µL-1; na tendinite do TFDS esquerdo (grupo controle, GC), foram injetados 2,5mL de solução salina a 0,9%. Após cinco dias, os animais foram submetidos à atividade física controlada e progressiva durante 30 dias. Os exames ultra-sonográficos foram realizados antes e após indução da tendinite (48 horas após e no 7º, 12º, 14º, 21º, 28º, 35º, 42º dias do experimento), sendo avaliado a área transversal do tendão (ATT), área transversal da lesão (ATL), o percentual da ATL, a intensidade e ecogenicidade da lesão, assim como o paralelismo das fibras colágenas. Os resultados revelaram redução (P<0,05) da ATL e do grau de ecogenicidade da lesão em função do tempo, mas com diferença (P<0,05) entre grupos apenas para ATL, com valores menores no GT. O tratamento com PRP proporciona maior redução da área da lesão, mensurada por ultra-sonografia.

Healing, Diagnosis, Repair, and Rehabilitation of Tendon Conditions

Management of tendon conditions can be frustrating due to difficulty with diagnosis, choice of treatment or repair technique, prolonged tissue healing, and potential for permanent compromise of limb function after surgery. This article reviews tendon healing and reported tendon conditions, focusing on bicipital tenosynovitis and common calcaneal tendon injuries. Surgical management options, research in enhancement of tendon healing, and postoperative rehabilitation are also reviewed.

Intralesional polysulphated glycosaminoglycan as treatment of equine collagenase induced tendinitis: clinical, ultrasonographic and histopathologic evaluation

The effect of intratendineous injections of polysulphated glycosaminoglycan (PSGAG) as treatment of collagenase-induced tendonitis was studied. Two groups (GI and GII) of five Arabian horses each, males and females, two to six year-old, were submitted to experimental tendinitis of the superficial digital flexor tendon of the left thoracic limb by intratendineous injection of 1.0ml of collagenase (2.5mg/ml). Seven days after the induced-lesions were created, the horses of GI received five intralesional injections of 1.0ml (125mg) of PSGAG, every four days. Horses of GII received injections of saline in the same dose and rate. Clinical and ultrasonographic evaluations were performed periodically, during 150 days. All animals showed lameness, increased local pain, heat and swelling 24 hours after the injury was created. All signs, except to swelling, which remained visible by the end of the study, showed regression in all animals. Lesions of variable size, shape and position were evidenced by the ultrasonographic evaluation, reaching maximum severity between the seventh and the 23rd days. By the end of the study, the echogenicity grade ranged from 1 to 2, and the grade of fiber alignment from 0 to 2. The histopathologic analysis demonstrated repair areas with intense fibroplasia and neovascularization, collagen fibers poorly organized, and thickened hypercellular endotenon. The data of this study did not show significant differences between the treated and control groups, therefore leading to the conclusion that the intralesional injection of PSGAG did not have beneficial effects in the treatment of collagenase-induced tendinitis.

The effects of extracorporeal shock-wave therapy on the ultrasonographic and histologic appearance of collagenase-induced equine forelimb suspensory ligament desmitis

Extracorporeal shock-wave therapy (ESWT) may stimulate healing of desmitis in multiple species. The objective of this study was to evaluate the ultrasonographic and histologic appearance of collagenase-induced suspensory ligament (SUL) desmitis in untreated ligaments and ligaments treated with ESWT in horses. Four mature horses had SUL desmitis induced in both forelimbs. Beginning 3 weeks after induction of the lesions, one ligament per horse was treated 3 times at 3-week intervals with ESWT. The percent lesion, echogenicity and fiber alignment scores of the SULs were evaluated at 3-week intervals for a total of 15 weeks. At the completion of the study, the horses were euthanized and the SULs collected, fixed and processed for histopathologic evaluation. Ultrasonography showed treated SULs had a smaller percent lesion at the maximal injury zone (p = 0.001), and the total percent lesion (p = 0.01), total fiber alignment score (p = 0.0167) and total echogenicity (p = 0.0023) were all smaller in the treated ligaments. The fiber alignment score and echogenicity were not statistically different at the maximal injury zone. The treated SULs had a more concentrated area of metachromasia associated with healing than the untreated ligaments, where metachromasia appeared more diffuse throughout the ligament. ESWT improved the rate of healing as assessed ultrasonographically.