Restoration of Lumbrical Function after Irreversible Ulnar Nerve Injury by Modified Bunnelís Procedure (A Report of Five Cases)

Research Article

Austin J Orthopade & Rheumatol. 2017; 4(1): 1050.

Restoration of Lumbrical Function after Irreversible Ulnar Nerve Injury by Modified Bunnel’s Procedure (A Report of Five Cases)

Ali Zein A.A. Alkhooly¹* and Ahmed Ali Z.A.A. Alkhooly²

¹Department of Ortho and Trauma, Minia University hospital, Egypt

²Department of Ortho and Trauma, Matai General Hospital (El-Minia), Egypt

*Corresponding author: Ali Zein Alabdeen Ahmed Alkhooly, Department of Ortho and trauma, Minia University hospital, Egypt

Received: February 01, 2017; Accepted: March 14, 2017; Published: March 21, 2017

Abstract

Normal hand function depends on the balance between the extrinsicintrinsic and extensor-flexor muscle groups. Despite their small size, the intrinsic muscles, contribute about 50% of grip strength. Clawing, partial or total due to ulnar nerve palsy affects greatly, hand’s ability for fine movements, grip and skilful use along with loss of tactile sensation of hand, which usually precedes the motor weakness. We evaluated the functional results of Modified Bunnel’s procedure in management of 5 patients of claw hand deformity. After a mean follow up of 16 months (range 12-24 months) results were excellent in 2 (40%) cases, good in 3 (60%). All the patients had improvement in the grip. No patient had Swan-neck deformity, flexion contracture, check-rein deformity, insufficient finger flexion, or superficial minus deformity. Despite being simple procedure, Modified Bunnel’s procedure results in less adhesion, straight course for the tendons, good grip and leverage. The patients were satisfied with their hand function and cosmetic appearance.

Keywords: Claw hand; Ulnar nerve; Modified bunnels procedure

Introduction

The primary goals of tendon transfer procedures for ulnar nerve palsy are restoration of small and ring finger DIPJ flexion restoration of key pinch, correction of clawing, integration of MCPJ and IPJ flexion, and improvement in grip strength [1].

Many different tendon transfer procedures for restoration of key pinch have been described, including the use of wrist and finger extensors, finger flexors, and the brachioradialis to power adductor pollicis function. Both the ECRB (Smith) [2] and brachioradialis (Boyes) [3] are strong donor that can be used to restore key pinch, The ring or middle finger FDS can also be used to restore adductor pollicis function (Littler) [4]. The use of finger extensors such as the EDQ, the index EDC, and the EIP has also been described.

Correction of clawing requires correction of MCPJ hyperextension, the problem that initiates clawing. Procedures can be categorized as static or dynamic. If Bouvier’s test is positive, static procedures may be successful. Osseous blocks on the dorsum of the metacarpal head have been described [5]. Zancolli described an MCPJ capsulodesis, in which a distally based flap of the volar plate was advanced proximally and sutured to the metacarpal neck, effectively limiting MCPJ extension [6]. Bunnell described a partial release of the A1 and A2 pulleys to allow bowstringing of the flexor tendons [7]. This results in increasing the moment arm of the flexor tendons at the MCPJ, thereby preventing MCPJ hyperextension. Static tenodesis with a tendon graft can also be performed. This type of static tendon graft effectively limits the amount of MCPJ extension [8].

Dynamic tenodesis can also be performed, as popularized by Fowler and Tsuge [9-11]. A tendon graft is looped through the extensor retinaculum at the wrist The two free ends of the tendon graft are passed through the intermetacarpal spaces into the palm, along the course of the lumbricals, and out to the fingers where they are inserted to the lateral bands. When the wrist is flexed, an active tenodesis effect occurs, resulting in MCPJ flexion and IPJ extension.

In the modified Stiles-Bunnell procedure [7,12] the ring finger superficialis tendon is divided distally in the finger and retrieved into the palm. It is then split into four slips. Each slip is then passed along the path of the lumbrical, volar to the deep transverse metacarpal ligament, and back into the finger, where it is inserted on the lateral band. Burkhalter recommended inserting the tendon on the proximal phalanx instead of the lateral band, thereby preventing PIPJ hyperextension [13]. Zancolli described a “lasso” insertion, wherein the FDS is passed through the A1 pulley, then sutured back onto itself, resulting in improved MCPJ flexion while avoiding PIPJ hyperextension [6].

An insertion into the lateral band may be preferred if Bouvier’s test is negative (clawing is complex), but it should be remembered that PIPJ hyperextension may occur.

Brand, Riordan, and others described the use of wrist-level motors to treat clawing and integrate finger flexion as well as augment grip strength [11,14,15]. The FCR, ECRL, ECRB, or brachioradialis may be used. The insertion can be into the lateral band, the proximal phalanx, or the A1 or A2 pulley. The main advantage of these tendon transfer procedures over the superficialis transfers is that they improve rather than worsen grip strength. In addition, there is no great loss of function at the level of the wrist. Also, because the superficialis tendon is preserved, the transfer can be inserted on the lateral band with less chance of developing PIPJ hyperextension.

Materials and Methods

Five patients underwent reconstructive surgery via modified Bunnell’s procedure, were included in the study. Patients were initially clinical examined and classified as per Dharmendra’s classification [16]. Preoperatively, grasp was subjectively assessed by dynamometer and muscle strength charting as well as sensory function examination were done and pre-operative photograph of the hand was taken (Figure 1).