The Use of Ultrasound in Evaluating Flexor Tendons following Surgical Repair

Abstract

Sir:FigureZone 1 and 2 flexor tendon repairs are associated with difficult repairs and poor outcomes. Clinical scores cannot differentiate between repair rupture and tendon adhesions in a poorly scoring digit. Ultrasound is not used routinely postoperatively but is used when concern regarding the integrity of the repair exists. High-resolution transducers can be used to assess repair integrity, tendon excursion, and adhesions.1,2 This study aimed to assess whether ultrasound can accurately evaluate zone 1 and 2 flexor tendon repairs and whether imaging provided useful clinical information. A series of patients attended postoperatively for ultrasound of their injured digit. Inclusion criteria were zone 1 and 2 complete flexor tendon lacerations. Concomitant neurovascular injuries were included, but patients with additional injuries were excluded. Patients underwent tendon repair with a four-strand core tendon repair using a 3-0 polypropylene suture and a 6-0 polypropylene epitendinous suture. Subjects were splinted dorsally for 6 weeks, and early active mobilization was commenced. Between postoperative weeks 6 and 8, the injured digit(s) and the uninjured contralateral digit were scanned. High-frequency (12-MHz) linear array ultrasound including color flow Doppler was performed at rest and during active flexion and extension. For each tendon repair site, repair integrity, tendon thickness, tendon glide, presence of adhesions, and vascularity were recorded. Corresponding values were obtained from the contralateral uninjured digit. Tendon glide was graded as unimpaired or mildly, moderately, or severely impaired. Vascularity was noted as equal, increased, or decreased compared with normal. A Strickland score was calculated for each injured digit.3 Paired samples t tests were carried out. A value of p ≤ 0.05 was considered significant. Ultrasonic data of the tendon repair were compared with the scanned uninjured tendon and the Strickland score. Fifteen patients participated with a total of 17 injured digits and 23 injured tendons. Nine had neurovascular injuries. Ultrasound scans were obtained at a mean of 50 days postoperatively. The majority of Strickland scores were good/excellent (eight) or fair (six). Three had poor scores. All repairs were imaged intact. Vascularity was increased in two patients. High-quality images of flexor tendons, repair sites, neurovascular bundles, and annular pulleys were obtained consistently (Figs. 1 and 2). When adhesions were present, the distinction between tendon and scar tissue was difficult but possible. On dynamic scanning, tendon glide was easily visualized.Fig. 1: Transverse color Doppler image of a digit in which the radial digital artery but not the ulnar digital artery has been repaired. The flexor tendons are visible in the center of the image, with the two flexor digitorum superficialis slips inferior to the flexor digitorum profundus tendon.Fig. 2: Transverse view of zone 2 flexor digitorum profundus repair close to the proximal interphalangeal joint. The two white spots at the center top part of the image are end-on views of the suture material. The flexor digitorum superficialis slips are directly underneath the repaired flexor digitorum profundus tendon.On average, flexor tendon repair sites were 50 percent thicker in the anteroposterior diameter and 25 percent wider in the radioulnar diameter compared with unrepaired tendons (p = 0.001). Two digits had unimpaired tendon glide, six had mild impairment, six had moderate impairment, and three had severe impairment of glide. Sixty percent of those with good/excellent Strickland scores had good tendon mobility compared with 25 percent of those with fair scores. Ultrasound provided tangible, clinically relevant information about surgical repairs and clinical progress of patients. High-frequency linear array probes of a small size are ideal for hand imaging, providing clear images with excellent resolution of anatomical structures and dynamic images of tendon glide.4,5 Our study confirmed the feasibility of using ultrasound in this patient cohort. Ultrasound is useful in identifying tendon rupture or excessive adhesions, and could be used as a method of stratifying patients with poor outcomes to the appropriate rehabilitation program. Nora Nugent, F.R.C.S.I.(Plast.) Department of Plastic and Reconstructive Surgery Joseph Coyle, M.B., B.Ch. Josephine Barry, M.R.C.P., F.R.C.R. Department of Radiology Michael O'Shaughnessy, F.R.C.S.(Plast.) Department of Plastic and Reconstructive Surgery, Cork University Hospital, Wilton, Cork, Ireland DISCLOSURE No financial support was received for this study and none of the authors has any financial interests to declare.