Mallet injuries can be classified (according to the Doyle system) into four types:
Type 1. Closed injury with or without avulsion fracture
Type 2. Open injury with tendon laceration
Type 3. Open injury with tendon substance and soft tissue loss
Type 4. Mallet fracture
This last type is further divided into three subtypes:
a) Transphyseal fracture in children,
b) hyper-extension injury with involvement of the 20-50% of the articular surface,
c) hyper extension injury with more than 50% of the articular surface involved.
Both tendinous and bony mallet injuries present with extensor lag at the distal interphalangeal joint. Typically, tendinous mallet injuries are low energy injuries that occur in older persons and are usually painless. On the other side, bony mallet injuries are high energy injuries and are typically painful. The authors also point out that tendinous mallet injuries typically involve the middle and ring fingers while bony mallet injuries are more common with the ring and little fingers. Have you noticed this fact with your mallet injured patients?
The authors also share another important fact: bony mallet injuries are hyperextension injuries and so the position of healing must be in neutral or even slight flexion but not in hyperextension in the orthosis. Orthoses for bony mallet injuries might be needed for a shorter duration than the much longer healing period associated with extensor tendon healing.
The authors conducted a retrospective study assessing the treatment of acute bony and tendinous mallet injuries treated with an orthosis in patients aged 18 and under. 31 participants were included in the study: 16 with bony mallet injuries and 15 with tendinous mallet injuries. All participants received a circumferential finger orthosis in a neutral position. Participants with the tendinous mallet injuries wore the orthosis for 6 weeks and the participants with a bony mallet participants wore the orthosis for 4 weeks. Both groups went through a gradual withdrawal of the orthosis in the following 3 -week period. Results of this study showed no significant difference in extension lag between the two groups with most patients achieving an excellent or good result. The authors did find a statistically significant difference in age: the bony mallet patients had an average of 13.8 years and the tendinous mallet patients had an average age of 11.93 years. In addition, most of the patients with the bony mallet injured their right hand while the patients with tendinous mallet injured their left hands.
In summary, most mallet injuries are treated in a similar manner with an orthosis that immobilizes the distal interphalangeal joint in extension and worn for a period of 6-8 weeks.
This study points out the significant differences between bony mallet injuries and tendinous mallet injuries and suggests not only a different position for the orthotic intervention, but also a shorter time frame for orthotic wear. Although this retrospective study evaluated the results of a relatively small group of young patients, it might be important to include these guidelines when treating older patients as well.
You can click here to access our online course of Mallet injuries on our virtual platform, the Orfit Academy, and watch 5 different ways to fabricate a mallet orthosis.
Another method of orthotic fabrication of the mallet orthosis is available on YouTube.
Reference
Rubin, G., Eliyahu, A. H., Mano, U. D., Shay, R., Svorai, S., Sagiv, R., … & Rozen, N. (2024). The outcome difference between acute bony and tendinous mallet fingers treated conservatively in children. Journal of Hand Therapy.
Written by Debby Schwartz, OTD, OTR/L, CHT
Physical Rehabilitation Product and Educational Specialist at Orfit Industries America.
Debby is a certified hand therapist with over 36 years of clinical experience. She completed her Doctorate of Occupational Therapy at Rocky Mountain University of Health Professions in 2010. She has worked at Orfit Industries America as Product and Educational Specialist since 2007.
Debby is also an adjunct professor at the Occupational Therapy Department of Touro University, School of Health Sciences, and at the Occupational Therapy Department at Yeshiva University, Katz School of Science and Health in NYC. She has written many book chapters in the field of hand therapy and multiple articles for hand therapy journals, including the ASHT Times and the Journal of Hand Therapy. She has published a new textbook on orthotic fabrication together with Dr. Katherine Schofield, entitled “Orthotic Design and Fabrication for the Upper Extremity: A Practical Guide”.
