Differential Splintage for Flexor Tendon Rehabilitation: An Experimental Study of its Effect on Finger Flexion Strength

Comparison of Treatment Outcomes of Different Immobilized Finger Positions After Repair of Flexor Tendon Rupture in Zones I and II: A Nonrandomized Controlled Trial With Historical Control Group

Introduction The position of finger immobilization after flexor tendon rupture repair is changed to the extended position to prevent flexion contracture of the interphalangeal (IP) joint. However, in Strickland's assessment, We believe that a reduction in TAF (total active flexion) affects the outcome and that extension fixation is not necessarily the primary focus. For example, there are management methods that swap the fixed position between day and night. It is assumed that some effect is sought by placing the fingers in the flexed position. That is, the method of fixation is currently selected at individual facilities through twists and turns; however, the indications and criteria for selecting finger fixation positions are ambiguous, and they are apparently subject to the experience of therapists. This study aimed to characterize follow-up outcomes of flexion and extension fixation after zones I and II flexor tendon rupture repair. Methods This nonrandomized controlled trial with historical controls included 25 patients with flexor tendon ruptures of 30 fingers. The flexion fixation group consisted of 12 patients (n=16 fingers) and the extension fixation group consisted of 13 patients (n=14 fingers). The group with flexion fixation comprised patients who slept with their injured fingers in the flexed position (intervention group). The group with extension was retrospectively selected between April 2017 and March 2019, who slept with their injured finger in the extended position (historical control group). Strickland assessments of the range of motion (ROM) of each joint at the conclusion of hand therapy, the ratio of total active motion of the repaired, to the healthy finger (%TAF), and IP joint extension limitation angles were compared using Mann-Whitney U tests. Ratios of excellent and good ratings based on the Strickland assessment were compared using Fisher exact tests. Result The results of the Strickland assessment showed excellent or good outcomes for 22 (73%) of 30 fingers, which was in line with our previous findings. Strickland ratings of excellent were achieved in seven (44%) of 16 fingers and four (28%) of 14 fingers in the groups with flexion and extension fixation, respectively. The outcomes for two (22%) of 16 fingers and seven (78%) of 14 fingers in the groups with flexion and extension fixation were, respectively, rated as good. The proportion of patients rated as excellent was significantly higher in the group with flexion than extension fixation (p=0.040). The %TAF and the active flexion angle of the distal interphalangeal (DIP) joint were higher in the group with flexion than extension fixation (p=0008 and p=0.025, respectively). Furthermore, the total angle of the IP joint limit of extension did not significantly differ between the groups. Conclusion Flexion fixation after flexor tendon rupture achieved an excellent Strickland rating and was more effective than extension fixation, especially in terms of the active flexion ROM of the DIP joint. Flexion fixation might be an alternative to extension fixation because the range of flexion should be greater and might provide a range of finger extension motion equivalent to that of extension fixation.

Relative motion flexion following zone I-III flexor tendon repair: Concepts, evidence and practice

STUDY DESIGN

Narrative review and case series.

INTRODUCTION

The relative motion approach has been applied to rehabilitation following flexor tendon repair. Positioning the affected finger(s) in relatively more metacarpophalangeal joint flexion is hypothesized to reduce the tension through the repaired flexor digitorum profundus by the quadriga effect. It is also hypothesized that altered patterns of co-contraction and co-inhibition may further reduce flexor digitorum profundus tension, and confer protection to flexor digitorum superficialis.

METHODS

We reviewed the existing literature to explore the rationale for using relative motion flexion orthoses as an early active mobilization strategy for patients after zone I-III flexor tendon repairs. We used this approach within our own clinic for the rehabilitation of a series of patients presenting with zone I-II flexor tendon repair. We collected routine clinical and patient reported outcome data.

RESULTS

We report published outcomes of the clinical use of relative motion flexion orthoses with early active motion, implemented as the primary rehabilitation approach after zone I-III flexor digitorum repairs. We also report novel outcome data from 18 patients.

DISCUSSION

We discuss our own experience of using relative motion flexion as a rehabilitation strategy following flexor tendon repair. We explore orthosis fabrication, rehabilitation exercises and functional hand use.

CONCLUSIONS

There is currently limited evidence informing use of relative motion flexion orthoses following flexor tendon repair. We highlight key areas for future research and describe a current pragmatic randomized controlled trial.

Use of a relative motion flexion orthosis for postoperative management of zone I/II flexor digitorum profundus repair: A retrospective consecutive case series

STUDY DESIGN

A retrospective, single-center, consecutive case series.

INTRODUCTION

In concept, a relative motion flexion (RMF) orthosis will induce a "quadriga effect" on a given flexor digitorum profundus (FDP) tendon, limiting its excursion and force of flexion while still permitting a wide range of finger motion. This effect can be exploited in the rehabilitation of zone I and II FDP repairs.

PURPOSE OF THE STUDY

To describe the use of RMF orthoses to manage zone I and II FDP 4-strand repairs.

METHODS

Medical record review of 10 consecutive zone I and II FDP tendon repairs managed with RMF orthosis for 8 to 10 weeks in combination with a static dorsal blocking or wrist orthosis for the initial 3 weeks.

RESULTS

Indications included sharp lacerations (n = 6), ragged lacerations (n = 2), staged flexor tendon reconstruction (n = 1), and type IV avulsion (n = 1). In 8 of the 10 cases that completed follow-up, the mean arc of proximal interphalangeal/distal interphalangeal active motion were as follows: sharp, 0° to 106°/0° to 75°; ragged, 0° to 90°/0° to 25°; reconstruction, 0° to 90°/10° to 45°; and avulsion, 0° to 95°/0° to 20°. Grip performance available for 6 of 10 cases was 62% to 108% of the dominant hand. There were no tendon ruptures, secondary surgeries, or proximal interphalangeal joint contractures.

CONCLUSION

Based on this small series, the RMF approach appears to be safe and effective. It can lead to similar mobility and functional recovery as other early active motion protocols, with certain practical advantages and without major complications. Further investigation with larger, multicenter, prospective, longitudinal cohorts and/or randomized clinical trials is necessary.

BIOMECHANICS AND HISTOLOGICAL ANALYSIS IN RABBIT FLEXOR TENDONS REPAIRED USING THREE SUTURE TECHNIQUES (FOUR AND SIX STRANDS) WITH EARLY ACTIVE MOBILIZATION

Objective: Analyzing suture time, biomechanics (deformity between the stumps) and the histology of three groups of tendinous surgical repair: Brazil-2 (4-strands) which the end knot (core) is located outside the tendon, Indiana (4-strands) and Tsai (6-strands) with sutures technique which the end knot (core) is inner of the tendon, associated with early active mobilization. Methods: The right calcaneal tendons (plantar flexor of the hind paw) of 36 rabbits of the New Zealand breed (Oryctolagus cuniculus) were used in the analysis. This sample presents similar size to human flexor tendon that has approximately 4.5 mm (varying from 2mm). The selected sample showed the same mass (2.5 to 3kg) and were male or female adults (from 8 ½ months). For the flexor tendons of the hind paws, sterile and driven techniques were used in accordance to the Committee on Animal Research and Ethics (CETEA) of the University of the State of Santa Catarina (UDESC), municipality of Lages, in Brazil (protocol # 1.33.09). Results: In the biomechanical analysis (deformity) carried out between tendinous stumps, there was no statistically significant difference (p>0.01). There was no statistical difference in relation to surgical time in all three suture techniques with a mean of 6.0 minutes for Tsai (6- strands), 5.7 minutes for Indiana (4-strands) and 5.6 minutes for Brazil (4-strands) (p>0.01). With the early active mobility, there was qualitative and quantitative evidence of thickening of collagen in 38.9% on the 15^th day and in 66.7% on the 30^th day, making the biological tissue stronger and more resistant (p=0.095). Conclusion: This study demonstrated that there was no histological difference between the results achieved with an inside or outside end knot with respect to the repaired tendon and the number of strands did not affect healing, vascularization or sliding of the tendon in the osteofibrous tunnel, which are associated with early active mobility, with the repair techniques applied.