Elastic energy storage across speeds during steady-state hopping of desert kangaroo rats (Dipodomys deserti)

Small bipedal hoppers, including kangaroo rats, are thought to not benefit from substantial elastic energy storage and return during hopping. However, recent species-specific material properties research suggests that, despite relative thickness, the ankle extensor tendons of these small hoppers are considerably more compliant than had been assumed. With faster locomotor speeds demanding higher forces, a lower tendon stiffness suggests greater tendon deformation and thus a greater potential for elastic energy storage and return with increasing speed. Using the elastic modulus values specific to kangaroo rat tendons, we sought to determine how much elastic energy is stored and returned during hopping across a range of speeds. In vivo techniques were used to record tendon force in the ankle extensors during steady-speed hopping. Our data support the hypothesis that the ankle extensor tendons of kangaroo rats store and return elastic energy in relation to hopping speed, storing more at faster speeds. Despite storing comparatively less elastic energy than larger hoppers, this relationship between speed and energy storage offer novel evidence of a functionally similar energy storage mechanism, operating irrespective of body size or tendon thickness, across the distal muscle-tendon units of both small and large bipedal hoppers.

Radiographic Landmarks for Ideal Port Placement in Wrist Arthroscopy

Background The placement of wrist arthroscopy portals is traditionally performed using distances from anatomic landmarks. We sought to evaluate the safety of traditional portal placement and determine if radiographic landmarks could provide an additional method of identifying tendon intervals. Methods Six cadaveric specimens were used to evaluate the accuracy of portal placement based on anatomic and radiographic landmarks. Fluoroscopic images were used to document the location of previously described surface landmarks. Soft tissue was dissected away to identify the relationship between the transcutaneously placed portals and the extensor tendons. With soft tissue removed, tendon intervals were identified in relationship to anatomic carpal bone landmarks, and interval distances measured. Portals were then placed under radiographic imaging on the final three specimens and accuracy was examined by the removal of overlying soft tissue to confirm accurate interval placement Results The 3,4 portal was safely placed using only surface anatomic landmarks, however the 4,5 and midcarpal ulnar (MCU) portal sites were not consistently placed in the intended tendon interval, especially in larger wrists. Radiographic interval targets for the 3,4 portal were identified at the ulnar aspect of the scaphoid and the 4,5 portal at the ulnar one-third of the lunate. The radiographic site for the MCR was located at the inferior radial one-third of the capitate and the MCU portal was located at the radial aspect of the hamate. The 6R portal radiographic landmark is at the radial aspect of the triquetrum and 6U at the ulnar aspect of the triquetrum. Conclusion Portal placement in wrist arthroscopy based on anatomic landmarks alone can be unreliable in larger wrists. Radiographic imaging based on carpal bone landmarks provides an additional tool for consistent placement of portals in wrist arthroscopy and may limit unintended injury to extensor tendons. Level of Evidence This is a Level VI study.

Tubercular Tenosynovitis of Extensor Tendons of Ankle : A Case Report

Introduction:India being an endemic region for Tuberculosis (TB) has a high incidence of musculoskeletal TB with various presentations. Tenosynovitis is a rare presentation and few cases have been reported involving the hand and wrist but isolated involvement of extensor tendons at the ankle is even rarer and unreported. Case Report:Thirty-five-year-old female patient presenting with a dumbbell-shaped swelling over the anterolateral aspect of right ankle with mild dull aching pain. MRI revealed altered signal intensities surrounding the extensor tendons at the ankle without the involvement of the joint. Surgical debridement was done and six-month ATT was given. Gross specimen revealed rice bodies and histopathological examination showed caseous necrosis and epitheloid cell granulomas. Conclusion:Tuberculosis TB being endemic can have varied presentations, early diagnosis can be made if clinical suspicion for TB is considered. ATT is the mainstay of treatment, but surgical debridement is necessary for extensive lesions with compressive symptoms. Keywords:Tuberculosis, tenosynovitis, rice bodies, dumbbell dumbbell-shaped mass.

Evidence for the Presence of Synovial Sheaths Surrounding the Extensor Tendons at the Metacarpophalangeal Joints

Background. MRI-detected inflammation around the metacarpophalangeal (MCP-)joints is prevalent in RA and poses a markedly increased risk of RA-development when present in arthralgia patients. Such inflammation is called ‘peritendinitis’, since anatomy literature reports no presence of a tenosynovial sheath at these tendons. However, the presence or absence of a synovial sheath at these extensor tendons has never been studied. Methods. A macroscopy and microscopy study of extensor-tendons at the MCP-joints of two embalmed human hands was performed. Routine histology was performed with Haematoxylin-Eosin staining. Results. We found evidence for the presence of synovial lining around extensor-tendons at MCP-joints. A delimited space surrounding the extensor digitorum tendon was observed, which was lined with an epithelium representing fibroblast-like synoviocytes. Conclusion. Contrast-enhancement around extensor tendons at MCP joints observed on MRI in RA represents tenosynovitis and thus inflammation of synovial tissue. Further studies with larger numbers of specimen are warranted to study anatomic variants. In addition, the molecular composition of the tenosynovium remains to be characterized.

The Effect of early active Movement following Repair of Extensor Tendons in Zone IV using three different suture Techniques – A cadaveric Study

Purpose The aim of this study was to investigate the effects of early active movement on the area repaired with three different suture techniques used in extensor tendon injuries in zone IV. Materials and Methods A total of nine cadaver’s 35 extensor tendons from 9 intact upper extremities were used in this study. The proximal and distal borders of the extensor tendons in zone IV were marked. The distance between the proximal and distal border was measured with a 0.5 mm precision tape measure and the mid-point was marked. Intertendinous connections were dissected and loop sutures were prepared for each extensor digitorum. Afterwards, force was applied to each digit along the tendon axis from the loops inserted into the extensor tendons, to measure the extensor forces required to extend the MCP joints to 0˚ with a hand scale. The flexor tendons of the digits were dissected at zone III, and loop sutures were prepared individually for the tendons to enable independent flexion for each digit. The force required to fully flex the digits was measured with a hand scale. The extensor tendons were incised transversely and repaired at the mid-point in zone IV with three different suture techniques (double Kessler, double figure of eight, running interlocking horizontal mattress (RIHM)). The extenxor tendon lengths in zone IV were re-measured for all digits after suturing. The predetermined forces required for full flexion and extension of the digits were applied to the repaired digits. After force was applied 20 times to each tendon, the gap formation was checked. Totally 200 flexion and 200 extension movements were applied to each finger with the help of a hand-held scale. Formation of 2-mm gap was failure criteria. At the end of the movements the extent of the gaps was recorded. In the absence of insufficiency at the repair site, 50 additional flexion and extension movements with double the previously recorded forces were applied to the tendons. Results There was a significant shortening of the extensor tendons after repair independent from the used suture technique. No significant gap formation was detected in all three suture techniques. Conclusion All three suturing techniques are reliable for early active movements following the zone IV extensor tendon repairs. Therefore, surgeons can choose one of those three suture techniques to repair extensor tendon injuries in zone IV.

Ultrasound Examination and Navigation for Repeat/Delayed Reconstruction of the Ankle Extensor Tendons

Herein, we describe a 46-year-old woman with persistent pain and weakness in her left ankle/foot one year after surgical repair of all three ankle extensor tendons following a penetrating injury. This report presents a unique case whereby US imaging played a paramount role in the diagnosis and surgical management of a previous nonanatomic repair of the ankle extensor tendons after a penetrating injury one year prior. The above-quoted findings were subsequently corrected with end-to-end sutures. On the third postoperative month follow-up, the patient was free of any complaints or complications.

The extensor tendons

The extensor tendon system of the hand includes the forearm-based extrinsic extensors that power wrist and finger extension as well as the hand-based intrinsic extensors that stabilize the digits in extension. The anatomy and interaction of these tendons are described with reference to the topographic classification system of Verdan’s zones. The injuries of the extensors can be either closed or open and the treatment is injury and site specific. The approaches to the individual injuries and treatment are described.

VAUGHAN JACKSON SYNDROME DUE TO DISTAL RADIOULNAR JOINT OSTEOARTHRITIS: A CASE REPORT

Spontaneous extensor tendons rupture (Vaughan Jackson syndrome) is a common complication of rheumatoid arthritis, but it is also reported sporadically with non-rheumatoid osteoarthritis of the distal radioulnar joint (DRUJ). We described a case of 45 years old female who lost her ability to extend the little, ring and middle fingers sequentially after months of wrist pain and limitation of movement due to osteoarthritis of DRUJ. The condition was treated surgically by tendon transfer and ulnar head excision. The patient did well after surgery.