Case Study: Osteosynthesis, Tenodesis Effect, and Side-to-Side Tendon Repair in Hand Transplantation

Upper Extremity Tendon Transfers: A Brief Review of History, Common Applications, and Technical Tips

Background  Tendon transfer in the upper extremity represents a powerful tool in the armamentarium of a reconstructive surgeon in the setting of irreparable nerve injury or the anatomic loss of key portions of the muscle-tendon unit. The concept uses the redundancy/expendability of tendons by utilizing a nonessential tendon to restore the function of a lost or nonfunctional muscle-tendon unit of the upper extremity. This article does not aim to perform a comprehensive review of tendon transfers. Instead it is meant to familiarize the reader with salient historical features, common applications in the upper limb, and provide the reader with some technical tips, which may facilitate a successful tendon transfer.

Learning Objectives  (1) Familiarize the reader with some aspects of tendon transfer history. (2) Identify principles of tendon transfers. (3) Identify important preoperative considerations. (4) Understand the physiology of the muscle-tendon unit and the Blix curve. (5) Identify strategies for setting tension during a tendon transfer and rehabilitation strategies.

Design  This study was designed to review the relevant current literature and provide an expert opinion.

Conclusions  Tendon transfers have evolved from polio to tetraplegia to war and represent an extremely powerful technique to correct neurologic and musculotendinous deficits in a variety of patients affected by trauma, peripheral nerve palsies, cerebral palsy, stroke, and inflammatory arthritis. In the contemporary setting, these very same principles have also been very successfully applied to vascularized composite allotransplantation in the upper limb.

Prosthetic Rehabilitation and Vascularized Composite Allotransplantation following Upper Limb Loss

BACKGROUND

Upper limb loss is a devastating condition with dramatic physical, psychological, financial, and social consequences. Improvements in the fields of prosthetics and vascularized composite allotransplantation have opened exciting new frontiers for treatment and rehabilitation following upper limb loss. Each modality offers a unique set of advantages and limitations with regard to the restoration of hand function following amputation.

METHODS

Presented in this article is a discussion outlining the complex considerations and decisions encountered when determining patient appropriateness for either prosthetic rehabilitation or vascularized composite allotransplantation following upper limb loss. In this review, the authors examine how psychosocial factors, nature of injury, rehabilitation course, functional outcomes, and risks and benefits may affect overall patient selection for either rehabilitative approach.

RESULTS

This review summarizes the current state of the literature. Advancements in both prosthetic and biological strategies demonstrate promise with regard to facilitating rehabilitation following upper limb loss. However, there remains a dearth of research directly comparing outcomes in prosthetic rehabilitation to that following upper extremity transplantation.

CONCLUSIONS

Few studies have performed a direct comparison between patients undergoing vascularized composite allotransplantation and those undergoing prosthetic rehabilitation. Upper extremity transplantation and prosthetic reconstruction should not be viewed as competing options, but rather as two treatment modalities with different risk-to-benefit profiles and indications.

Side-to-Side Versus Pulvertaft Extensor Tenorrhaphy-A Biomechanical Study

PURPOSE

We hypothesized that a side-to-side (STS) tendon repair has biomechanical characteristics that match those of a Pulvertaft (PT) weave.

METHODS

Thirty extensor tendons were harvested (4 extensor digitorum communis and 1 extensor indicis proprius from 6 cadaver arms). Three hand surgery fellows with similar backgrounds of training under the same conditions and precise standardized technique performed the repairs (5 PT and 5 STS per surgeon). After the repairs, the tendons were passed through a graft-sizing guide to determine bulk and results were expressed as a repaired versus native diameter ratio. The specimens were then tested for ultimate strength and fatigue properties. Failure type and mechanical properties were recorded and compared with those of the native tendon.

RESULTS

The average peak force to failure was 93 ± 20 N for the STS and 62 ± 32 N for PT group. Relative strength ratio (repair strength compared with native tendon strength) was 37% ± 21% for the STS and 22% ± 11% for the PT group. In the STS group, all failures occurred as a result of tissue failure; however, in the PT, suture failures occurred in 3 tendons before tissue failure. The mean bulk ratio of the repaired site versus native proximal tendon was 37 ± 14% and 40% ± 22% more for the STS and PT groups, respectively. These values for native distal tendon were 28% ± 9.9% and 26% ±24 %, respectively for STS and PT repair. Furthermore, the bulk of the repaired site for the STS and PT groups was 4.2 ± 0.50 and 4.7 ± 1.2 mm, respectively.

CONCLUSIONS

Side-to-side repair technique showed superior biomechanical properties while demonstrating comparable repair bulk of the tendon coaptation compared with the Pulvertaft weave.

CLINICAL RELEVANCE

The results of this study may help guide a surgeon's choice of repair technique when addressing tendon injuries or tendon transfers.