Background: Penetrating trauma or lacerations within zone II of the flexor sheath may result in partial tendon injury. The proper management of this injury is controversial; the literature contains differing indications for surgical treatment and postoperative rehabilitation.
Methods: A literature review of the Cochrane, MEDLINE, and PubMed databases was performed using the following search criteria: partial, flexor, tendon, and laceration. All English language studies that evaluated biomechanical strength, complications, and outcomes after partial tendon injury in human and animal studies were included and reviewed by two of the authors.
Results: Animal and cadaveric biomechanical studies have demonstrated that partial lacerations involving up to 95 percent of the tendon cross-sectional area can safely tolerate loads generated through unresisted, active finger flexion. Suture tenorrhaphy of partial tendon injury is associated with decreased tendon tensile strength, increased resistance, and decreased tendon gliding. Complications of nonsurgical management include triggering and entrapment, which can be managed by tendon beveling or pulley release. Late rupture is extremely uncommon (one report).
Conclusions: Partial tendon lacerations involving 90 percent of the cross-sectional area can be safely treated without surgical repair and immediate protected active motion. Indications for exploration and treatment include concern for complete injury, triggering of the involved digit, or entrapment of the tendon. Surgical treatment for tendon triggering or entrapment with less than 75 percent cross-sectional injury is beveling of the tendon edges and injuries greater than 75 percent should be repaired with a noncircumferential, simple epitendinous suture. All patients should be allowed to perform early protected active motion after surgery.