A 62-year-old steelworker presented for treatment of his right small finger contracture. The proximal interphalangeal (PIP) joint was contracted to 70 degrees, associated with an abductor digiti minimi cord. He had previously had a fasciectomy in his left ring finger and first web space, which was complicated by a flare reaction. As a result, he struggled to regain flexion of all digits and was unable to return to work for 6 months. After discussion of treatment options, he chose clostridial collagenase histolyticum (CCH) treatment for his right small finger contracture.
The injection was performed per manufacturer’s guidelines, injecting 0.58 mg of clostridial collagenase into three contiguous areas of the cord. A manipulation was performed the following day, without anesthesia, resulting in cord rupture and near-full passive extension. The patient was fitted for an extension splint to wear at nighttime, and instructed in a home range of motion (ROM) exercise program. Eight days following the injection, the patient had returned to his job. While gripping a pallet jack to move a heavy pallet, he felt a pop in the treated finger.
Physical examination demonstrated typical sequela of collagenase injection including mild edema and mild ecchymosis (▶Fig. 8.1). Sensation was intact; however, the patient had no active flexion of the distal interphalangeal (DIP) joint, and decreased active flexion of the PIP joint. Diagnosis of rupture of the flexor digitorum profundus (FDP) tendon, with an intact flexor digitorum superficialis (FDS), was made and confirmed by magnetic resonance imaging.
Two-stage reconstruction is the recommended option following tendon rupture, particularly when both tendons fail. It requires two surgeries, separated by 4 to 6 months, and potentially a third tenolysis procedure. This is a significant time and financial commitment, however, and is best suited for patients able to be compliant and diligent with their rehabilitation.
Acceptance of an FDS-only finger can be the best choice for many patients with isolated FDP rupture, particularly those with a preexisting stiff DIP joint. Wanting to avoid surgery, our patient initially choose observation and therapy to regain active PIP motion. Six weeks later, the patient continued to have limited PIP flexion as well as pain in the palm, and was indicated for excision of the tendon stump and FDS tenolysis, still refusing tendon reconstruction and preferring the more rapid recovery of an FDS-only finger.
The risk of tendon rupture as a result of collagenase injection, and how to mitigate against it, should be thought about during every injection. There are likely multiple factors involved in a patients’ risk of tendon rupture. Location plays a key role, with all three ruptures occurring in the clinical studies following injection for PIP contracture in the small finger. Of the 26 ruptures reported in the 3 years following Food and Drug Administration (FDA) approval, 13 involved the small finger (5 metacarpophalangeal [MCP] and 8 PIP), 4 involved the ring finger MCP, and 9 were unidentified. As the cord moves distally in the finger, it becomes closer to the flexor sheath. Additionally, there is less space between the skin and the flexor sheath at the PIP joint (4 mm) compared to the MCP joint (7 mm). Extreme care should be taken while performing CCH injections. The syringe must be stabilized during the injection to prevent the needle from moving outside of the cord. During injection, a significant amount of resistance should be felt. If resistance is lost, extravasation outside of the cord is happening, and the needle should be moved to a new location in the cord. For digital cords, injections should be placed proximally whenever possible, utilizing the “safe zone” of no more than 4 mm distal to the proximal digital flexion crease. The cord can be injected so that the needle points away from the flexor sheath using a more horizontal injection aiming laterally. If the cord is particularly thin, surgeons should consider using less than the full 0.58-mg dose, particularly when injecting distal to the proximal digital flexion crease. Finally, we counsel patients to avoid forceful gripping and lifting for 3 to 4 weeks following injection, to allow for collagen remodeling.
• Tendon reconstruction:
– Primary repair not advised due to zone of injury and tendon quality.
– Two-stage reconstruction:
◦ Placement of tendon rod and FDS excision (if present).
◦ Removal of rod and tendon graft after wound quiescence.
• DIP joint fusion.
• Acceptance of FDS-only finger.
The stump of the FDP tendon was freed of scar tissue, and the lumbrical origin released. The tendon was excised. Tenolysis of the FDS was performed proximal to the A1 and A2 pulleys and between the A2 and A4 pulleys, until tension on the proximal FDS tendon resulted in full PIP flexion. The patient started immediate postoperative therapy for edema control and ROM exercises.
The patient regained full active MCP joint motion and PIP joint motion of 45 to 80 degrees. He was able to return to his manual labor job. Follow-up evaluation 3 years following treatment, the patient had lost extension at the PIP joint with ROM of 70 to 92 degrees (▶Fig. 8.3). There was no palpable Dupuytren’s tissue. The recurrent flexion contracture was therefore felt to be primarily due to arthrofibrosis and extensor mechanism attenuation, two factors that lead to recurrent and residual PIP contractures in patients with long-standing severe PIP contractures regardless of primary treatment method.
CCH is a mixture of two purified bacterial enzymes that act to lyse the highly stable triple-helical type I and III collagens comprising Dupuytren’s cords. The synergistic activity of these two enzymes results in rapid degradation of fibrillar collagen tissue, weakening the cord, and allowing for subsequent elongation and rupture. The by-product of this action are small collagen fragments that trigger three characteristic physiologic responses: vascular leakage, neutrophil chemotaxis, and wound-healing response.