The relative motion concept in acute and chronic boutonniere deformity: Invited commentary

STUDY DESIGN

Retrospective.

INTRODUCTION

Boutonniere deformity (BD) is a troublesome injury occurring from rupture of tissue connecting the extrinsic to intrinsic tendon systems. This causes loss of interphalangeal joint balance, and immobilization often results in adherence and difficulty restoring balance.

PURPOSES

Review of relative motion flexion (RMF) orthotic use for safe healing during functional activity in 23 patients, and explanation of the rationale.

METHODS

Anatomic rationale and clinical experience is reviewed in 8 acute BD patients utilizing RMF orthoses for 6 weeks, and for chronic BD patients, 3 months after serial casting.

RESULTS

All patients met the Strickland and Steichen criteria for "excellent" results following treatment, with an average of 35° increase in ROM.

DISCUSSION

The anatomic rationale for relative motion recognizes that altering relative positioning between adjacent metacarpophalangeal (MCP) joints produces a protective favorable impact on interphalangeal forces during hand function using 15°-20° greater MCP joint flexion. This provides dorsal and volar protective benefits because the extensor digitorum communis (EDC), a single-muscle-four-tendon system, attaches to the intrinsic lateral band (LB) tendons. With greater MCP flexion, dorsal EDC force is increased, pulling lateral bands medially, while on the volar surface the downward pull of the lumbrical on LB is relaxed due to origin from the flexor digitorum profundus tendon of the injured digit, also a single-muscle-four-tendon system. The RMF orthosis permits protected active motion during functional activity with acute BD. In patients with chronic BD and adequate passive extension, an RMF orthosis for 3 months also produced encouraging results.

CONCLUSION

Management of acute BD with RMF orthoses provided earlier recovery of motion and hand function. Similar results occurred for chronic BD using serial casting for adequate extension followed by 3 months of RMF orthotic use and should be attempted prior to surgical intervention, with surgery remaining an alternative.

Extensor Tendon Injuries in the Athlete

An athlete's hands are susceptible to a variety of acute and cumulative traumas depending on their chosen sport. Depending on the timing of the injury, the immediate requirements of the athlete, and future aspirations, treatment strategies may need individual customization. This article offers a brief review of the anatomy and complex function of the extensor mechanism, discusses the etiologies of various extensor injuries, and outlines the multiple treatment options and expected outcomes.

Treating the Proximal Interphalangeal Joint in Swan Neck and Boutonniere Deformities

Swan neck and boutonniere deformities of the proximal interphalangeal (PIP) joint are challenging to treat. In a swan neck deformity, the PIP joint is hyperextended with flexion at the distal interphalangeal (DIP) joint. In a boutonniere deformity, there is flexion the PIP joint with hyperextension of the DIP joint. When the deformities are flexible, treatment begins with splinting. However, when the deformity is fixed, serial casting or surgery is often necessary to restore joint motion before surgical correction. Many surgical techniques have been described to treat both conditions. Unfortunately, incomplete correction and deformity recurrence are common.

Biomechanics of the Acute Boutonniere Deformity

PURPOSE

To demonstrate which structures of the extensor mechanism create a boutonniere deformity, when damaged, in a cadaver model. An analysis of how damage to these anatomical structures affects the biomechanical performance of the extensor mechanism was also performed.

METHODS

We secured 18 fresh cadaveric hands onto an apparatus consisting of a computer-controlled motor and tensiometer attached in series to the extensor communis tendon of the ring and middle digits. The central slip, transverse, and oblique fibers of the interosseous hood and the triangular ligament were sequentially divided. After each structure was divided, the motors were activated to provide a constant tendon displacement force. The angular displacement at the proximal interphalangeal (PIP) and distal interphalangeal joints was recorded.

RESULTS

In all digits, detachment of the central slip from the middle phalanx produced a decrease in extension of the PIP joint. When the transverse and oblique fibers of the interosseous hood were also divided, extension at the PIP joint was further decreased. A boutonniere deformity occurred only when all 3 structures were damaged.

CONCLUSIONS

The boutonniere deformity requires subluxation of the lateral bands volar to the axis of rotation of the PIP joint. This study demonstrates that damage to the central slip alone does not cause the deformity. Combined injury of the central slip, triangular ligament, and transverse and oblique fibers of the interosseous hood causes a boutonniere deformity.

CLINICAL RELEVANCE

Division of the central slip leads to loss of extension at the PIP joint. A more substantial loss of extension after injury or development of a boutonniere deformity should alert clinicians that other structures of the extensor mechanism are also damaged.

Relative motion orthoses in the management of various hand conditions: A scoping review

STUDY DESIGN

Scoping review.

INTRODUCTION

The relative motion (RM) concept and immediate controlled active motion (ICAM) program, originally applied after zones IV-VII extensor tendon repairs, have been modified and extended to a variety of hand conditions, such as sagittal band injury, boutonniere deformity, and extensor lag.

PURPOSE OF THE STUDY

To scope the published and unpublished literature to review ICAM modifications, hand conditions for which the RM concept is used, and describe the preferred degree of relative metacarpophalangeal joint extension/flexion reported and spectrum of orthosis design.

METHODS

Electronic and manual searches of scientific and gray literature and expert consultation were conducted. Documents with quantitative data were assessed with Oxford Levels of Evidence and the Structured Effectiveness Quality Evaluation Scale.

RESULTS

Fifteen references met the inclusion criteria; 1 was level III evidence, and others were level IV evidence. RM-ICAM modifications, preferred degree of relative extension/flexion, orthotic design, management of other hand conditions and knowledge gaps were identified.

CONCLUSION

RM orthoses may improve outcomes in a variety of hand conditions; however, high-quality studies that contribute to the evidence base for its use are needed.

LEVEL OF EVIDENCE

Not applicable.

Postburn Contractures of the Hand

Postburn contractures are a common occurrence after severe burn injuries. It is important to understand the pathologic condition and anatomy of specific postburn deformities in order to provide comprehensive surgical care. Postburn contractures can result in a flexion contracture, boutonniere deformity, burn syndactyly, metacarpophalangeal extension contracture, wrist contracture, or claw hand. A patient evaluation is performed before proceeding to the operating room. Surgery sequences require proper incision design, release of the skin, and deeper contracted structures and coverage with an appropriate flap or graft. Postoperative splinting, scar care, and therapy are equally important for a successful outcome.