Anomalous extensor muscles of the hand: a review.

Anomalous extensor muscles of the hand are not uncommon. Well-recognized anomalies anomalous extensor indicis proprius, extensor digitorum brevis manus, extensor medii proprius, and extensor indicis et medii communis are reviewed and discussed in detail. Anomalous extensor indicis proprius and extensor digitorum brevis manus may occasionally give rise to dorsal wrist pain and the diagnosis is often confused especially in the presence of other pathologic findings such as a ganglion. An analysis of the embryologic development of the extensor muscle mass with phylogenetic comparisons between species of the animal kingdom is presented to underscore the clinical relevance of these anomalous extensors.     

Management of extensor mechanism deficit as a consequence of patellar tendon loss in total knee arthroplasty: a new surgical technique

Extensor mechanism disruption is an uncommon but devastating complication of total knee arthroplasty. A new technique of extensor mechanism reconstruction for patellar tendon loss, after total knee arthroplasty, with the help of extensor mechanism composite allograft is described. Four patients with chronic extensor mechanism-deficient total knee arthroplasty were undertaken for revision surgery along with reconstruction of extensor mechanism with an innovative technique using an extensor mechanism composite allograft consisting of a patella-patellar tendon-tibial tubercle. On final follow-up, none of the patients had extensor lag but for 10 degrees of extensor lag in 1 patient only. Providing an environment for bone-to-bone healing both proximally as well as distally and supervised postoperative rehabilitation led to encouraging results in the management of a failed extensor mechanism after total knee arthroplasty.     

Partial extensor carpi radialis longus turn-over tendon transfer for reconstruction of the extensor pollicis longus tendon in the rheumatoid hand: case report

Reconstruction of a distally ruptured extensor pollicis longus tendon in the rheumatoid patient generally involves a tendon transfer or intercalary graft. We present an alternative technique using the radial half of the extensor carpi radialis longus as a turn-over graft. Using the turn-over technique with a half-slip of the extensor carpi radialis longus avoids the traditional limitations of the extensor carpi radialis longus tendon in distal extensor pollicis longus tendon repairs and precludes the need for a free tendon graft.     

Variations of the extensor indicis muscle and tendon

Variations of the extensor indicis muscle were examined in 164 hands from 86 Japanese cadavers. Anomalous cases exhibiting supernumerary muscles or tendons were found in 22 hands. These variations were classified into four types: type 1, an additional tendon slip from the extensor indicis tendon; type 2, an extensor indicis radialis or extensor pollicis et indicis accessorius; type 3, an extensor medii proprius with or without extensor medii brevis; and type 4, an extensor indicis radialis and extensor medii proprius. The extensor medii proprius was the most common variation, followed by extensor indicis radialis. There were no clear differences in incidence of variations between men and women or between right and left hands. When variations were bilateral, both sides were identical or similar in type.     

Variations of the posterior interosseous nerve

The posterior interosseous nerves of 58 cadaver forearms of black South Africans were dissected to study their order of branching. In 43 specimens (74%), the most common order of branching was: extensor carpi radialis brevis; supinator; extensor digitorum; extensor carpi ulnaris; extensor digiti minimi; abductor pollicis longus; extensor pollicis brevis; extensor pollicis longus and extensor indicis. In 15 specimens (26%) different variations of the nerve were observed, some of which are reported for the first time. The knowledge of these variations could be useful during operations in the vicinity of the nerve, and when repairing a nerve injury or forecasting the location of a compressive lesion.     

Snapping Wrist due to an Anomalous Extensor Indicis Proprius: A Case Report

Variation in the extensor muscles of the hand is common. These anatomic deviations are rarely symptomatic. We report a unique case of an anomalous extensor indicis proprius causing a painful snapping wrist. Intraoperative examination revealed a disproportionately large muscle belly under the extensor retinaculum causing subluxation of the ring and small extensor tendons creating a painful snapping phenomenon. Following excision, the subluxation and pain resolved.     

The centralization of extensor tendons during wrist surgery

After a wrist surgery in patients with rheumatoid arthritis, the extensor tendons have a tendency to shift toward the ulnar side of the wrist. This is caused by the dorsal tenosynovectomy, disruption of extensor retinaculum, and exteriorization and anatomical orientation of the superficial group of forearm extensor tendons. This article describes a technique as an adjunct to the wrist surgery, which aims to stabilize and centralize tendons of the fourth dorsal wrist compartment over the midline of the wrist. This is achieved by creating a distally based sling, harvested from the extensor carpi radialis longus tendon, then wrapped around the extensor digitorum communis and the extensor indicis proprius tendons, and finally anchored onto the extensor carpi radialis brevis. This adjunctive procedure is recommended in situations when after the wrist surgery, particularly wrist arthroplasty, tendons of the fourth dorsal wrist compartment tend to lay ulnar to the central axis of the hand.     

Bilateral extensor digitorum brevis manus

Dorsal wrist pain and swelling is commonly attributed to a dorsal wrist ganglion. However, based on the authors' experience, a cautious surgeon should keep the uncommonly symptomatic diagnosis of an extensor digitorum brevis manus in their differential despite classic ganglion presentation and suggestive advanced imaging.This article describes a case of a young patient who presented with bilateral symptomatic extensor digitorum brevis manus anomalies that required surgical intervention. An extensor digitorum brevis manus is present in 3% of the population in a classic anatomy study from Japan and is most commonly symptomatic with heavy activity and extremes of wrist extension. Anatomically, the extensor digitorum brevis manus is located in the fourth wrist compartment and most commonly inserts on the index finger extensor mechanism. Examination often reveals a spindle-shaped mass that is palpable distal to the extensor mechanism and moves with extensor tendon motion. Magnetic resonance imaging shows a typical dorsal mass distal to the common extensors with a similar signal as muscle with all image sequencing. Treatment includes activity alterations to relieve symptoms or surgical excision of the muscle belly for refractory cases with care taken to preserve the index extensor mechanism.     

A new modification of extensor indicis proprius transfer to extensor pollicis longus using a retinacular pulley

A new modification of the extensor indicis proprius transfer to the extensor pollicis longus tendon through a fourth dorsal compartment retinacular pulley is described. This new modification has been assessed in cadavers biomechanically via computer simulation and in a limited number of patients with success. It affords the benefit over the standard subcutaneous extensor indicis proprius to the extensor pollicis longus tendon transfer of maintaining the adduction moment arm of the thumb. The moment arm mechanics of the pulley transfer resemble those of the intact extensor pollicis longus. Therefore this new modification offers better thumb function in both adduction and circumduction motions.     

Extensor mechanism allografts in total knee arthroplasty.

Forty knees in 40 patients who had a chronic extensor mechanism disruption after knee arthroplasty underwent extensor mechanism allograft placement to restore extensor function. Thirteen knees were infected previously and 11 knees did not respond to previous attempts at direct extensor repair or reconstruction. Two patients died and two patients underwent above the knee amputation because of recurrent infection. The final group of 36 patients was studied for a mean followup of 3.6 years (range, 2-10 years). Clinical evaluations were performed using a modified Knee Society scoring system. The average range of motion in the entire group of patients was 1.4 degrees extension to 98 degrees flexion. The average extensor lag was 13 degrees in 15 of 36 patients. There were eight extensor allograft ruptures, which were treated by repeat extensor allograft placement. The average knee scores for function improved from 37 points preoperatively to 68 points postoperatively. Despite these initial ruptures, 34 of 36 patients had a successful clinical result. These results support the use of this technique for complete extensor mechanism loss after knee arthroplasty when direct repair is unfavorable.     

Central slip tenotomy for the treatment of chronic mallet finger: an anatomic study

PURPOSE: Tenotomy of the central slip, described by Fowler, can clinically improve chronic distal interphalangeal joint (DIP) extensor lag secondary to mallet finger (terminal tendon disruption). The goal of this study is to evaluate the potential of central slip tenotomy to restore DIP joint extension. METHODS: A mallet deformity was reproduced in 15 fresh-frozen cadaver fingers after the extensor tendon insertion was sectioned over the DIP joint. A suture anchor inserted at the terminal insertion was then secured to the extensor tendon over the middle phalanx to reconstruct the extensor mechanism. A 500-g weight attached to the proximal extensor tendon applied extensor tension. Central slip tenotomy was then performed. DIP extensor lags before and after tenotomy were recorded. RESULTS: After sectioning of the terminal tendon over the DIP joint the average amount of extensor tendon lag produced was 45 degrees. After central slip tenotomy was performed the average amount of extensor lag correction was 36 degrees (range, 30 degrees-46 degrees). CONCLUSIONS: Several clinical studies have shown that central slip tenotomy is an effective treatment for chronic mallet finger but may not fully restore DIP joint extension. Our data suggest that patients with a pre-existing extensor lag of greater than 36 degrees may not achieve full extension from central slip tenotomy, although extensor lags of up to 46 degrees may be corrected.     

Posttraumatic volar tendon subluxation out of the first extensor compartment: a case report

Symptomatic volar subluxation of the abductor pollicis longus and the extensor pollicis brevis tendons developed in a 29-year-old man after a sprain that occurred with the wrist in flexion and ulnar deviation. The extensor retinaculum, which forms the extensor compartment, was partially avulsed from its insertion on the radius. Palmar abduction and extension of the thumb with the wrist flexed produced subluxation of the tendons over the volar side of the radius ridge where the retinaculum forming the first extensor compartment attached. Nonoperative treatment including steroid injection and splinting was ineffective. Surgery was performed to reconstruct a new tendon restraint with part of the extensor retinaculum.     

Anatomical study of the ankle with view to the anterior arthroscopic portals

This article evaluates the risk of interference with the neurovascular structures in the four anterior ankle arthroscopic portals, described on each side of the extensor tendons: anteromedial, medial midline, anterocentral and anterolateral. Complications after ankle arthroscopies have been described in up to 17%, most being neurovascular. To quantify the neurovascular risks we dissected 68 cadaveric feet and evaluated the correlations between tendons, vessels and nerves. The mean distance between tibialis anterior and extensor hallucis longus and between extensor hallucis longus and extensor digitorum longus is 4 mm, but in 10-20% these tendons are in apposition or are overlapped. The tibialis anterior vascular bundle was absent in 11.8%, was located between the tibialis anterior and the extensor hallucis longus in 3% and between the extensor hallucis longus and the extensor digitorum longus in 64.7%. A peroneal vascular bundle or branches of the tibialis anterior vascular bundle were located lateral to the extensor digitorum longus/peroneus tertius tendon in 88.2%. Transverse vascular branches were identified in 41.2% over the medial side of the joint line and in 52.9% over the lateral side. The deep peroneal nerve was located between the extensor hallucis longus and the extensor digitorum longus tendons in 58.8%. The superficial peroneal nerve had branches located between the tibialis anterior and the extensor hallucis longus tendons in 2.9%, between the extensor hallucis longus and the extensor digitorum longus tendons in 23.5% and lateral to the extensor digitorum longus/peroneus tertius tendon in 32.4%. These results show that the anteromedial and medial midline portals are the safest. The anterolateral portal should be noted not only for the risks to the superficial peroneal nerve, but also to the peroneal vessels.     

Double triggering of extensor digiti minimi: a case report

Extensor tendon triggering is a rare disease entity. Even less common is a case of extensor digiti minimi (EDM) double triggering caused by impingement on the extensor retinaculum. Herein, we describe one patient with EDM double triggering developed at the extensor retinaculum and over the metacarpal head caused by its impingement on the extensor retinaculum.     

Problems and solutions of the extensor mechanism

Problems related to the extensor mechanism can be devastating and severely compromise the end result of revision knee replacement surgery. Many of these complications can be prevented by careful surgical technique, especially intraoperative avulsion of the patellar tendon. Fractures of the patella in the most extreme forms can lead to prosthetic loosening and disruption of the extensor mechanism. In the most severe cases, complete absence of the extensor mechanism may require allograft extensor mechanisms to restore extensor function. Alterations in rehabilitation and postoperative treatment are often necessary to ensure an excellent result. Along with restoration of bone defects, achieving excellent knee alignment and stability, a functional and aligned extensor mechanism is key to an excellent result in knee revision surgery.     

Anatomic variation of the extensor tendons to the ring and little fingers: a cadaver dissection study.

We found an anatomic variation of the extensor digiti minimi (EDM) and extensor digitorum communis (EDC) in a cadaveric dissection. The EDM had three tendon slips; two slips to the little finger and one to the ring finger metacarpophalangeal (MP) joint. The ring finger slip inserted in the extensor hood with the EDC. The EDC had a separate tendon to the little finger extensor hood. The EDM had an additional pulley distal to the extensor retinaculum. The MP joints of the little and ring fingers extended simultaneously upon pulling the EDM or the EDC. The third slip of the EDM could provide an extra donor site and possibly poses a unique clinical presentation.     

Unusual case of closed rupture of both extensor tendons of the index finger

Extensor tendon rupture is a common condition following penetrating injuries, whereas closed rupture is rare unless in a mallet finger. We describe an unusual case of closed rupture of both extensor tendons to the index finger. The extensor indicis proprius and extensor digitorum longus were avulsed proximal to the extensor retinaculum in a 23-year-old male patient due to forced hyperflexion of his index finger. Investigation was done in the Department of Orthopaedic Surgery at the Notre Dame Des Secours University Hospital, Byblos Lebanon.     

The management and physiotherapy of extensor tendon injuries

Summary The investigation and management of extensor tendons play a minor role compared to those of flexor tendons. The finger extension does not seem to be as important as the flexion. But the practical value of the hand is determined by both. Different managements are used depending on the level of extensor tendon injury. More distal located injuries require a longer restraint than those, which are located more proximal. On the one hand this depends on the blood supply of the extensor tendon, which is by far better in the lower arm and dorsal hand than peripheral. On the other hand the reason is the different amplitude of gliding of extensor tendons, which decreases from proximal to distal to lower than 1 mm. Therefore the tension on extensor tendon sutures increases from proximal to distal. The varies techniques of extensor tendon reconstruction will be described.      

The role of supinator in the pathogenesis of chronic lateral elbow pain: a biomechanical study

The relative contributions of the forearm extensors to the tensile force at the lateral epicondyle were examined by implanting a force transducer in the common extensor tendon of four soft fixed cadaver elbows and sequentially stretching each muscle arising from the lateral epicondye. Extensor carpi radialis brevis and extensor digitorum communis produced the largest increases while the superficial head of supinator produced a moderate increase in tensile force in the common extensor tendon. Extensor carpi radialis longus and extensor carpi ulnaris had no significant effect. Radial tunnel pressure was measured using a balloon catheter in a separate study of five cadaver elbows. Radial tunnel pressure increased on moving the wrist from neutral to a flexion-pronation position. This positional rise in pressure was reduced by supinator musculotendinous lengthening (77%) while lengthening of the extensor carpi radialis brevis and extensor digitorum communis had no effect. This study demonstrates a biomechanical basis for the superficial head of supinator in the aetiology of both lateral epicondylitis and radial tunnel syndrome.     

Extensor carpi ulnaris problems at the wrist--classification, surgical treatment and results

Twenty-eight extensor carpi ulnaris lesions at the wrist were treated surgically between 1990 and 2002. Fifteen patients had an isolated extensor carpi ulnaris tenosynovitis or tendinopathy, five had extensor carpi ulnaris dislocation, four had an extensor carpi ulnaris subluxation and four had an extensor carpi ulnaris rupture. Seventeen patients first developed their symptoms while playing sports. At a mean follow-up of 23 months, twenty-two patients had returned to their previous activities. Seven of the 27 patients had lost more than 30% of their grip strength and five had restricted wrist motion. Two needed an extensor carpi ulnaris tenolysis. Pure isolated extensor carpi ulnaris lesions are rare and associated ulnar sided lesions (eleven triangular fibrocartilage complex tears and four lunotriquetral ligament tears), as well as possible predisposing factors (seven anomalous tendon slips, four ulnar styloid non-unions and one flat extensor carpi ulnaris tendon groove), were frequent. A classification of extensor carpi ulnaris tendon and subsheath lesions was developed to allow the surgeon to adequately evaluate the different components of these lesions.