1. Nader Paksima DO, MPH Clinical Professor of Orthopedic Surgery – NYU Grossman School of Medicine
2. Paul Izard BS Research Coordinator – Department of Orthopedic Surgery, NYU Langone Health
3. Elizabeth Kietz PA-C, MS Advanced Practice Provider (APP) Manager

Abstract
We report here a useful test for clinicians to determine the progress of conservative mallet finger treatment. This test can be performed as early as two to three weeks post-injury.

Background
“Mallet finger” is a disruption of the terminal extensor tendon at the distal interphalangeal (DIP) joint. It is a common injury and may be strictly a soft tissue injury or it may also include an avulsion fracture of the distal phalanx articular surface.¹ Clinically, it is characterized by the inability to actively extend the distal phalanx, leading to the characteristic “drooping” appearance. Treatment can be non-operative or operative, with similar outcomes reported between methods in uncomplicated acute cases. There are several surgical and nonsurgical management techniques described in the literature. The standard practice for conservative mallet finger treatment is to splint the injured finger continuously for six to eight weeks, and then nighttime splinting for 4 weeks. This is often reported to be successful, and splinting alone can be expected to treat 80% of cases.^2-3 However, there can be some amount of deformity, extensor lag, and residual joint pain reported by patients after healing, as well as a small bump on the dorsal aspect of the joint. Surgical treatment is considered when the patient presents with large bony fragments (>30% of the articular surface), joint subluxation or if the patient has functional limitations like pain or substantial residual lag after conservative treatment. However, the residual droop is often a cosmetic problem rather than a functional problem.  We report here a method to evaluate the progress of conservative treatment earlier in the healing process.

Procedure for the Lift-off Technique to Evaluate Early Healing (Performed Around 2-3 Weeks Post-Injury)

1. Prevent inadvertent DIP flexion by placing the palm of the patient’s injured hand on a flat surface such as a table before carefully removing any splinting.
2. Direct the patient to lift the injured finger, while inhibiting the adjacent FDP by keeping the adjacent digits flat on the table.
3. Observe any extensor lag of the injured distal phalanx.

Discussion
We created this lift-off test because during the six to eight weeks of splinting there is no method of evaluating the healing progress of the terminal tendon. Normally, removing the splint to check could allow the DIP joint to flex involuntarily, secondary to the flexor digitorum profundus (FDP) activity, stretching out the healing tendon. This test takes advantage of the common muscle belly of the FDP: by inhibiting FDP flexion of the adjacent digits, the FDP of the affected digit is inhibited from contracting and we can check the terminal tendon function. The full 6-8 weeks of splinting is needed to allow the damaged tissue to heal, followed by 4 weeks of nighttime extension splinting. We have observed that three weeks of continuous splinting is enough time to see if the extensor tendon has begun to heal, at which point the examination described above can take place. If the finger can maintain active extension, then not only can we feel confident that the treatment is working, but this visible evidence of healing can also encourage the patient. If the test fails, this allows the surgeon to change approaches earlier, resulting in less overall treatment time for the patient, and ideally, better outcomes as well.

Figure 1 | Figure 2

References

1. Lamaris GA, Matthew MK. The Diagnosis and Management of Mallet Finger Injuries. Hand (N Y). 2017;12(3):223-228. doi:10.1177/1558944716642763
2. Smit J, Beets M, Zeebregts C, Rood A, Welters C. Treatment Options for Mallet Finger: A Review. Plastic and Reconstructive Surgery. 2010; 126 (5): 1624-1629. doi: 10.1097/PRS.0b013e3181ef8ec8
3. Makhlouf VM, Deek NA. Surgical treatment of chronic mallet finger. Ann Plast Surg. 2011;66(6):670-672. doi:10.1097/SAP.0b013e3181e6d017
4. Barrios SAD, Serrano AFJS, Herrera JAG, Berumen MFR, Atanasio JMP. OUTCOME OF NON-SURGICAL TREATMENT OF MALLET FINGER. Acta Ortop Bras. 2020;28(4):172-176. doi:10.1590/1413-785220202804230335

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