The Management of Partial Zone II Intrasynovial Flexor Tendon Lacerations: A Literature Review of Biomechanics, Clinical Outcomes, and Complications

Abstract

Sir: We read with great interest the recent article entitled “The Management of Partial Zone II Intrasynovial Flexor Tendon Lacerations: A Literature Review of Biomechanics, Clinical Outcomes, and Complications,” by Lineberry et al.,1 published in Plastic and Reconstructive Surgery. We credit the authors for their extensive work in evaluating a large number of studies of variable methodologies, in an attempt to provide clarity on management of partial flexor tendon injuries. We agree with the authors’ conclusions that all suspected partial tendon lacerations should be explored surgically with direct visualization of the flexor tendon. However, we believe the authors are drawing conclusions from outdated research. Only four of 24 studies (16.6 percent) in this review were published after 2008. Over the past decade, there has been a dramatic evolution in flexor tendon management regarding suture material, tenorrhaphy techniques, and greater excursion on the repaired tendon postoperatively. Subsequently, we question the authors’ ability to make recommendations based on these studies, in particular, the grade (percent) of partial tendon laceration necessitating surgical repair and the type of tenorrhaphy when surgical intervention is required. Early active motion following flexor tendon repair encourages intrinsic healing and decreases adhesion formation.2 This postoperative therapy requires a strong, gap-free tenorrhaphy resisting forces up to 30 to 50 N.3,4 Gap formation within the repair is detrimental, as this correlates clinically to adhesion formation and rupture,5 especially for intrasynovial tendon injuries. Our department struggles to comprehend how a simple epitendinous-only repair in a partial flexor tendon laceration greater than 80 percent of the total tendon surface area can resist 2-mm gap formation during forces exerted during early active motion. Consequently, we conducted our own biomechanical assessment of 90 fresh porcine flexor digitorum profundus tendons. Partial lacerations of 70, 80, and 90 percent of the total tendon surface area were created with digital calipers. Thirty tendons in each partial laceration group were divided randomly into (1) no repair, (2) running epitendinous repair with 6-0 Prolene (Ethicon, Inc., Edinburgh, United Kingdom), and (3) four-strand Adelaide technique core repair with 3-0 Ethibond (Ethicon) with an epitendinous suture. Our findings support the authors’ conclusions that nonrepaired partial tendon lacerations of 90 percent have enough residual strength to resist rupture during early active motion. However, the forces creating 2-mm gap formation in partial lacerations of 80 percent (4.9 N) and 90 percent (3.8 N) are well below the requirements for early active motion. Tenorrhaphy with epitendinous sutures only increased resistance to the gapping to 25.1 N in the 80 percent and 15.9 N in the 90 percent partial laceration group. The addition of core suture significantly increased the resistance to 2-mm gap formation in both groups (p < 0.05). Results are displayed in Figure 1.Fig. 1.: A comparison of resistance to 2-mm gap formation between 70, 80, and 90 percent partial flexor digitorum profundus laceration.Up-to-date research on partial flexor tendon lacerations, as evident in this review, is rare. We have demonstrated that an epitendinous-only repair of partial tendon laceration greater than 80 percent does not provide adequate strength to prevent 2-mm gap formation during early active motion. We disagree with the authors’ conclusions and believe that partial tendon laceration greater than 80 percent should be managed similarly to a complete tendon laceration with both a core suture and an epitendinous suture. DISCLOSURE The authors have no financial interest to declare in relation to the content of this communication. Conor M. Sugrue, M.R.C.S., B.C.H., B.A.O.George Rahmani, M.R.C.S., B.C.H., B.A.O.Department of Plastic and Reconstructive SurgeryGalway University HospitalGalway, IrelandGSD CriúGalway, Ireland Jack L. Kelly, F.R.C.S.(Plast.)Department of Plastic and Reconstructive SurgeryGalway University HospitalGalway, Ireland