Locking finger due to a partial laceration of the flexor digitorum superficialis tendon: a case report

Partial Flexor Tendon Injury Causing Locking: Illustration of the Utility of Dynamic Ultrasound

Clinical diagnosis of partial flexor tendon lacerations is challenging because tendon function may be preserved. Although some partial flexor tendon tears can be managed conservatively, pain, stiffness, and triggering/locking may result, requiring surgical management. The mechanism by which this occurs has been investigated in animal and cadaver studies but has not been demonstrated in patients with real-time, in vivo imaging. Here, we present a case of partial tendon tear presenting with severe pain and locking that was diagnosed before surgery and characterized with dynamic ultrasound.

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

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.

Partial tendon tear as unusual cause of trigger finger: a case report

We report a case of post-traumatic trigger finger due to a partial longitudinal tear of the flexor digitorum superficialis. The suspect came from the clinical history and the young age of the patient. It was successfully treated with tendon flap suture and pulley A1 release.

Accuracy of Visual Estimates of Partial Flexor Tendon Lacerations

PURPOSE

To determine whether hand surgeons could accurately and consistently estimate the size of partial flexor tendon lacerations.

MATERIALS AND METHODS

Thirty-two partial flexor tendon lacerations were made in the flexor digitorum profundus tendons of a fresh-frozen cadaveric hand. Four hand surgeons and 5 residents estimated the size of the lacerations. Estimates were repeated 3 days later. Magnified images of the laceration cross-section were used to calculate the true size of each laceration. Inter- and intrarater reliability were calculated using the intraclass correlation coefficient. Accuracy was measured with the mean bias error and the mean absolute error.

RESULTS

Interrater and intrarater reliabilities were both high. There was a high level of consistency for both surgeons and residents. In terms of accuracy, there was a 3% bias toward underestimation. The mean absolute error was 11%. There was no statistically significant difference between the accuracy of attending hand surgeons and that of residents. Participants were less accurate when estimating lacerations close to a 60% laceration threshold for surgical repair (lacerations in the 50%-70% range). For lacerations within this range, an incorrect management decision would have been made 17% of the time, compared with 7% of the time for lacerations outside that range.

CONCLUSIONS

The accuracy and reliability of surgeon estimates of partial flexor tendon laceration size were high for surgeons and residents. Accuracy was lower for lacerations close to the threshold for repair.

CLINICAL RELEVANCE

Visual estimation is acceptable for evaluating partial flexor tendon lacerations, but it may be less reliable for lacerations near the threshold for repair. Therefore, surgeons should be cautious when deciding whether or not to repair partial lacerations in the borderline range.