Finger and thumb replantation: From biomechanics to practical surgical applications

Vascularized posterior interosseous nerve graft for digital neurovascular bundle reconstruction

INTRODUCTION

Despite the progress in microsurgery in recent decades, neurovascular bundle defects during ring finger injuries still pose challenges for the surgeon. Usually, a reversed venous graft and a non-vascularized nerve graft are utilized to reconstruct this defect. One of the most common challenges encountered when using a venous graft is the caliber mismatch between the graft and the digital arterial ends. The use of an arterialized nerve graft (neurovascular graft) is poorly described and could represent an attractive reconstructive option.

CASE PRESENTATION

We present the case of a 36-year-old manual worker, a non-smoker, with no significant medical or surgical comorbidities, who presented a ring avulsion type trauma, leading to the amputation of the third left finger at the distal interphalangeal joint and avulsion of the circumferential skin at the level of the middle and proximal phalanges (Urbaniak III). The patient presented a neurovascular bundle defect of 3 cm, reconstructed by the vascularized posterior interosseous nerve graft along the distal perforator of the dorsal branch of the anterior interosseous artery serving both as an interpositional arterial conduit and as a nerve graft. The results of postoperative nerve regeneration at three years are satisfactory, with the patient demonstrating a two-point discrimination measured at 6 mm.

CONCLUSION

Simultaneous digital artery and nerve reconstruction using a neurovascular flap is very appealing to the hand surgeon as it offers several advantages over traditional methods, particularly the ideal diameter match between the digital arteries and the distal perforator of the dorsal branch of the anterior interosseous artery.

REPLANTATION OF THE THUMB OR REVISION OF AMPUTATION: AN EPIDEMIOLOGICAL STUDY

OBJETIVE

This article presents a retrospective cohort study analyzing patients from IOT-FMUSP who underwent replantation or revision amputation procedures for traumatic thumb amputation between 2013 and 2020.

METHODS

The study included 40 patients in the replanted group and 41 patients in the amputed group. The patients were divided according to the level of amputation and their medical records were analyzed.

RESULTS

A total of 81 patients with digital amputation were analyzed, consisting of 79 males and 2 females, with mean ages of 43 and 49 for the amputed and replanted groups, respectively. According to the Biemer classification, 28.4% had proximal amputation, while 71.6% had distal amputation. The most common occupation was bricklayer (19.75%), and 80.24% were manual workers. Of the patients, 65% returned to their previous work, with 77.77% of them having amputation on their non-dominant hand, mostly caused by circular saw accidents (77.77%). The replantation success rate was 78%, with an average ischemia time of 9 hours and door-to-room time of 2 hours.

CONCLUSION

the study findings revealed that traumatic thumb amputation predominantly affects working-age males with a low education level and the success rate of replantation was high in this ischemia time and door-to-room conditions. Level of Evidence II, Retrospective study.

Patient-matched osseointegrated prostheses for thumb amputees: a cadaver and feasibility study

Thumb amputations affect 50% of hand functionality. Common solutions consist of microsurgical treatments or silicone vacuum prosthesis. Not all patients are eligible for microsurgical treatment and the use of vacuum prosthesis is often discouraged because of their instability. On the contrary, osseointegrated prosthesis provide stable retention and osseoperception. This cadaveric study evaluated the process of a patient-matched osseointegrated prosthesis for the treatment of thumb amputees. Computed tomography (CT) medical images reconstruction provided information on metacarpal stump, used as input for the parametric screw design. Preoperative planning guided the surgeons in the surgery: postoperative placement confirmed the accuracy of the preoperative planning. Surgeons were directly involved in the implant design to meet their requirements and patient needs. Implants were inserted into cadaveric specimens in one-stage surgery. A similar process can be adopted and exploited for the treatment of different levels of thumb amputations and long finger amputations.

A Challenging Case of Thumb Replantation Aided by Intraoperative Indocyanine Green Fluorescence Angiography

Background

This study presents a case of thumb replantation performed despite several risk factors: age, comorbidities, and trauma mechanism are major adverse prognostic factors directly impacting thumb replantation. Most of the literature backs up this claim that a thumb that works, even partially, is a better outcome for the patient than amputation.

Methods

We performed thumb replantation on a 94-year-old patient with type 2 diabetes mellitus who arrived at the emergency department with a thumb avulsion due to a dog bite. The intraoperative indocyanine green fluorescence angiography method aided us in carrying out the operation.

Results

We successfully used indocyanine green angiography intraoperatively to guide surgical debridement and evaluate the efficacy of anastomosis and reperfusion of the replanted segment during surgery. Two months after the operation, the patient had regained satisfactory hand function.

Conclusions

Although indocyanine green angiography is not a technology created for revascularization procedures, it is instrumental in assessing vascular function and predicting a successful outcome. Given its undeniable potential, more research is needed on the possibility of widespread use in hand surgery and its indications.

Evidence-based postoperative replantation protocols

Postoperative care is essential to upper extremity replantation success and includes careful and frequent monitoring of the replanted part. During this period, pharmacologic agents such as antithrombotic and anticoagulants may prevent complications such as arterial thrombosis and venous congestion. Dressings and therapy can also impact short- and long-term outcomes following replantation. This article reviews the literature to provide guidance for postoperative protocols following upper extremity replantation.

Predictors of Success following Microvascular Replantation Surgery of the Upper Extremity in Adult Patients

The purpose of this study is to ascertain which factors are associated with successful replantation in the upper extremity. Secondarily, the purpose was to determine patient factors that differentiate those patients who undergo initial replantation versus initial amputation.

Methods

Data gathered for this retrospective study were obtained from a custom subset of the 2015-2020 IBM Truven MarketScan Commercial and IBM Truven MarketScan Medicare Supplemental databases. Data were sorted using Current Procedural Terminology codes and International Classification of Disease, Ninth and Tenth Revision, diagnosis codes.

Results

Increasing age was significantly associated with undergoing initial amputation compared with replantation (P < 0.001; 95% CI, 47.146-50.654). Among comorbid conditions, patients with diabetes mellitus type II (2.4% versus 24.3%; P < 0.001), hypertension (11.9% versus 28.0%; P = 0.03), end-stage renal disease (0% versus 10.5%; P = 0.03), and hypertensive chronic kidney disease (0% versus 8.7%; P = 0.04) more commonly underwent an initial amputation procedure. When evaluating the need for secondary procedure after replantation, there was no statistical significance between groups when comparing age, gender, insurance type, general comorbidities, connective tissue disorders, mental health disorders, or geographic location.

Conclusions

In conclusion, this study demonstrates that age and the presence of comorbidities are important factors in the differentiation of which patients undergo initial reimplantation versus initial amputation. Additionally, no specific factors were identified that were associated with secondary procedures after replantation.

Application of Cryopreservation Technique in the Preservation of Rat Limbs

OBJECTIVE

The aim of this study was to observe the physiologic and pathologic changes of severed fingers (limbs) under different storage conditions through animal experiments, and to screen out the best preservation conditions.

METHODS

Sixty healthy adult male Sprague-Dawley rats were selected and evenly divided into 4 preservation groups, including conventional low-temperature dry (CLTD), the University of Wisconsin (UW) solution, cryopreservation, and cryopreservation + UW solution preservation group. After harvesting the limbs, were preservated for 72 hours and 7 days, respectively. Then the limbs were thawed and replanted in situ. Sciatic nerves were collected for hematoxylin & eosin (H&E) staining and observed the changes in tissue morphology.

RESULTS

Replantation was successful in 11 of 15 rats (73%) in the cryopreservation + UW group, and the walking function of the 9 (82%) rats in cryopreservation + UW group were significantly better than that of the cryopreservation preservation group. Additionally, the H&E staining results shown that the CLTD group nerve bundles were morphologically damaged, and there were more acellular structures and tissue fragments; the UW group nerve bundles were less injured and the perineurium was more complete and more orderly. The nerve bundles in the cryopreservation group and the cryopreservation + UW group are tightly arranged, and the tissue morphology is regular. Compared with the cryopreservation + UW group, the completeness of the cryopreservation group was not sufficient.

CONCLUSIONS

The cryopreservation technology combined with the UW solution is a new and effective method for preservation of severed limbs.