Functional Outcome of Double and Four Strand Techniques in Hand Flexor Tendon Repair

INTRODUCTION

14% to 30% of all treated patients examined in emergency rooms have hand injuries. Tendon injuries rank 2nd (29%), while fractures rank 1st (42%), among patients who have had hand injuries. The age group with the highest frequency is 20–29 years old, and the majority of patients are male ¹

Tendon injuries require precise and immediate repair. The outcome of flexor tendon repair is determined by a number of factors; in addition to understanding the anatomy and biomechanical behavior of tendons, the technique of tendon repair is critical  Core sutures associated with circumferential peripheral sutures are commonly used techniques for tendon repair The peripheral suture is said to be the repair's weakest link

Recent research has looked into and developed core suture methods to give the tendon repair more strength. Given that the peripheral suture is the weakest link, additional efforts should be made to improve this feature

Flexor tendon repair has traditionally relied on two-strand repair techniques. Savage introduced multi-strand repair, incorporating six suture strands across the repair site and demonstrating improved gap resistance and ultimate force. In the 1980s and 1990s, 4- or 6-strand repairs were developed. The development and widespread use of multi-strand repair methods in the last decade of the twentieth century has resulted in a significant change and simplification of these suturing techniques

Patients' post-operative management after flexor tendon repair has evolved over time, owing to advancements in surgical techniques and suture materials

Immobilization, early passive mobilization, early active mobilization, and combination protocols are the most common post-operative rehabilitation protocols, with management in the first three to six weeks being the most critical

Flexor tendon rehabilitation seeks to find the right balance between optimal ROM and normal tendon excursion while safeguarding the repair

Fig. 1: Summary of methods used in flexor tendon repairs ⁸

A review of comparative studies comparing the outcomes of passive versus active mobilization revealed conflicting results, and there is still considerable debate about optimal management protocols. Although current medical evidence favors early active mobilization for rehabilitation following flexor tendon repair

When it comes to the appropriate treatment and rehabilitation of flexor tendon injuries, any healthcare setting in both developed and developing countries faces a challenge. The primary metrics used to determine whether the flexor tendon repair and rehabilitation treatments were successful or unsuccessful are rupture rates and range of motion (ROM)

This is a prospective study to demonstrate the functional outcomes of double strand and four strand techniques in hand flexor tendon repair, as well as the effect of early rehabilitation.

PATIENTS AND METHODS

This is a randomly selected comparative prospective study that was carried out for 40 patients who had complete flexor tendon injury of the hand and were over the age of 15. Both males and females were chosen from those seeking treatment in the plastic and burn surgery department's outpatient clinic and emergency room at Al-Hussein & Bab Elsheria University Hospital, Faculty of Medicine, Al-Azhar University (Cairo). They all worked in our operating rooms.

Selection criteria: primary tendon injury. A patient who is more than 15 years old Males and females without selection. Hand flexor tendon injuries in any zone Complete tendon cut. Patients classified into random groups according to the modality of repair and early rehabilitation.

Exclusion criteria: patients younger than 15 years. Partial tendon cut. old cut. Infected wound associated skeletal injuries. Closed tendon rupture. Soft tissue loss. Segmental loss of tendon

Ethical approval: After explanation of the research project to the patients and/or their families, all questions from the patients regarding pre-operative, intraoperative, and post-operative steps are answered. A consent form was signed by the patients who participated in the study, and the study was carried out in accordance with the approval obtained from the ethics unit of the Faculty of Medicine, Al-Azhar University, Cairo, and the informed agreements obtained from the included participants.

Methodology

This is a randomly selected comparative prospective study involving 40 patients.

The study participants were randomly assigned to one of two groups; the first group included 20 patients who had their cores repaired using a two-strand modified Kessler technique. The second group of 20 patients was repaired using the four-strand technique.

Following that, each group was blindly subdivided into two subgroups of ten patients each: The first subgroup is subjected to early passive rehabilitation. The second subgroup is subjected to early active rehabilitation.

The surgical steps of flexor tendon repair in this study

General principles: Because neurovascular injury is common with flexor tendon injuries, a thorough examination is required prior to local anesthetic infiltration. A flexor tendon injury causes extension of the affected finger, distorting the resting digital cascade. Good lighting and magnification are considered mandatory steps in the operation. During surgical repair of the tendon, the pully system was preserved as much as possible, especially the A2 and A4 and even when the pully was incised, a repair for the pully was done to prevent bowstringing.

Preoperative evaluation

History intake and examination. Pre-operative photography and patient consent (Fig. 2). Pre-operative x ray to exclude any fractures (Fig. 3). Preoperative routine labs such as (CBC, kidney function, liver function, coagulation profile, and serum albumin).

Fig. 2: Pre-operative photography.

Fig. 3: Pre-operative x ray

Operative Steps

Position: The patients were operated on in a supine position.

Anesthesia: Most cases had the surgery under regional anesthesia with torniquet. most cases done under local anesthesia only 7 cases under brachial block (take in consideration not to exceed toxic dose of lidocaine 5mg/kg & Marcaine 2mg/kg) because of expected long operative time and 1 case under general anesthesia because the patient was young age and not cooperative. when the patients were awake, this helped us to assess the active motion of the repaired tendon intraoperatively.

Flap design: the incision is designed along the wound. A Bruner, or mid-axial, approach is typically used for exposure of the tendons. (Fig. 4)

Exploration of the wound and exposure of both ends of the tendon (Fig.5)

Fig. 4: Incision along the wound A Bruner approach used.

Fig. 5: Good exposure of both ends of tendon

Core suture techniques were used in this study.

Two-strand modified Kessler core suture (Fig.6): The repair is done with proline 3-0 non-absorbable sutures, modified Kessler technique used, then epi-tendinous 4-0 proline running circumferential suture was applied. 5-0 proline running sutures are used in patients with small tendon cores.

Four – strand technique (Fig.7): A four-strand suture with (3-0 polypropylene) and a simple running suture with (4-0 polypropylene)

Fig. 6: Modified Kessler technique

A. grasping B: locking

Fig. 7: Four-strand suture A modified double-lock by Kessler B: non-locked Cruciate C: cross-locked Cruciate 

Intra operative evaluation: Passive movement of the tendon to assess tendon repair and function (Fig. 8 & Fig.9)

Fig. 8: Intraoperative assessment (passive extension)

Fig. 9: Intraoperative assessment (passive flexion)

The plaster is applied after homeostasis and wound closure with 3-0 polyproline sutures.

When wearing a dorsal splint, the wrist is held in a 20° to 30° flexion, the MCP (metacarpophalangeal) joints are held in a 70° flexion, and the IP (interphalangeal) joints are held in neutral extension. (Fig.10)

Hand elevation is required following surgery.

Fig. 10: Dorsal splint, the wrist is held in a 20° to 30° flexion, the MCP (metacarpophalangeal) joints are held in a 70° flexion, and the IP (interphalangeal) joints are held in neutral extension.

Techniques of early rehabilitation in this study

Early passive rehabilitation: On the first postoperative day, the patient’s postsurgical dressing is removed. The patient is placed into a dorsal splint, the wrist is held in a 20° to 30° flexion, the MCP joints are held in a 70° flexion, and the IP joints are held in neutral extension. Passive range-of-motion exercises, such as passive flexion of the distal interphalangeal joint (DIP) and PIP joints, are initiated, both separately and in conjunction with composite finger flexion. Active extension from the fully flexed position is permitted to the splint's limits. Full flexion to the palm and full extension to the splint's limits should be part of the composite range of motion. At this initial visit, edema control is critical, which includes anti-edematous medications, hand elevation, and light compression with a bandage (Fig.11).

Fig. 11: Early passive rehabilitation of each joint

Early active rehabilitation

On the first postoperative day, the patient’s postsurgical dressing is removed. The patient is placed into a dorsal splint, the wrist is held in a 20° to 30° flexion, the MCP joints are held in a 70° flexion, and the IP joints are held in neutral extension. The exercises started with passive flexion of the digits followed by active extension to the splint's limits. (Fig. 12). After completing these exercises, the patient can begin active flexion exercises with the other hand as a guide and advance 1 finger width per week after the end of the first week.

Fig. 12: Active flexion exercises with advanced 1 finger width per week after the end of the first week.

Postoperative evaluation

Range of motion assessment: Total active movement (TAM). According to the Strickland classification, the American Society for Surgery of the Hand (A.S.S.H) introduced and recommended TAM. TAM is the sum of the flexion ranges at the three joints, minus the total extension lag. (Fig.13)

Fig. 13: Measuring range of motion by goniometer (Baseline® Finger Goniometers)

The injured digit's total active range is expressed as a percentage of the corresponding contralateral digits' total active range. The percentage value is then graded, as shown in Table 1  

Table 1:Active range of movement grading according to ASSH

Grip strength: The American Society of Hand Therapists proposed a standardised hand and arm position. The shoulder was neutrally adducted and rotated while measuring grip strength, and the wrist was held at 30° of dorsiflexion and 15° of ulnar deviation. The dominant hand was initially measured. With a Jamar dynamometer, measurements were taken in both hands, and it was assumed that the dominant hand had a power of 100 percent to 120 percent of the non-dominant hand. The grading system is shown in Table 2

Table 2: Grip strength grading system

Statistical Analysis

Data was gathered, revised, coded, and entered into IBM SPSS version 26, Microsoft Excel 2016, and MedCalC software version 19.1. When the distribution was found to be parametric, qualitative data was presented as numbers and percentages, while quantitative data was presented as mean, standard deviations, and ranges. The confidence interval was set at 95%, and the acceptable margin of error was set at 5%. As a result, the p-value was regarded as significant as follows: Non-significant (NS) means P greater than 0.05. A p value of less than 0.05 indicates statistical significance (S). p less than 0.001 denotes highly significant (HS).

RESULTS

Table 3: A distribution of the patients researched according to tendon affected

Table 4: A distribution of the patients researched according to zone of injury

P-value > 0.05: non-significant; P-value

Table 5: Comparison between methods of repair of the studied groups as regard range of motion and grip strength According to postoperative assessment data of the studied patients

P-value > 0.05: non-significant; P-value

Table 6: Comparison between methods of repair of the studied groups as regard complication

P-value > 0.05: non-significant; P-value

Table 7: Comparison between methods of early rehabilitation applied to the studied groups as regard range of motion and grip strength

P-value > 0.05: non-significant; P-value

Table 8: Comparison between methods of early rehabilitation applied to the studied groups as regard post operative complications

P-value > 0.05: non-significant; P-value

Table 9: Comparison between early rehabilitation sub groups of modified Kessler group as regard range of motion and grip strength

P-value > 0.05: non-significant; P-value

Table 10: Comparison between early rehabilitation sub groups of modified Kessler group as regard complications

P-value > 0.05: non-significant; P-value

Table 11: Comparison between early rehabilitation sub groups of the 4-strand group as regard range of motion and grip strength

P-value > 0.05: non-significant; P-value

Table 12: Comparison between early rehabilitation sub groups of the 4-strand group as regard complications.