HandLab Clinical Pearls

February 2021 No. 66

Regaining Synergistic Wrist Extension after Ending CMMS Too Early

Karol S. Young OTD, OTR/L, CHT


Figure 1: The CMMS cast blocks wrist and MP joint motion to isolate interphalangeal (IP) joint flexion and extension which 1) activates the extrinsic flexor muscles 2) reduces edema by stimulating the lymphatic system and 3) mobilizes stiff IP joints by repeated active movement.

Six weeks after carpal tunnel release to her non-dominant hand, Debbie, a 64 year-old active retiree, was seen in our clinic with a diagnosis of complex regional pain syndrome (CRPS). Many new patients with symptoms of prolonged edema, pain and stiffness of the wrist and hand are diagnosed with CRPS. The use of Casting Motion to Mobilize Stiffness (CMMS) (1) described by Judy Colditz, OTR/L, CHT, FAOTA, usually calms the CRPS symptoms which causes one to wonder if the diagnosis is accurate.

Although Debbie had been receiving therapy, she continued with unresolved edema, pain, and stiffness in her wrist and fingers. Having successfully used the CMMS technique, I explained the rationale to Debbie and she agreed to this treatment approach. See Figure 1.

Improvement with the CMMS cast

Debbie wore the CMMS cast for 18 days to activate her extrinsic flexor muscles, at which time her edema was substantially reduced, and her finger stiffness significantly improved (Figure 2). Although the CMMS technique advocates a slow weaning out of the cast to retain the re-established normal pattern of motion, Debbie discontinued her cast and her maladaptive motor pattern of wrist flexion with finger flexion reappeared. See Figure 3. Her limited passive wrist extension, wrist extensor muscle weakness, and a hypersensitive volar wrist scar contributed to her inability to extend her wrist actively when she flexed her fingers.

Figure 2. Active finger flexion after CMMS
Figure 3. Wrist flexion with finger flexion

Improving Wrist Joint Motion

To re-establish Debbie’s synergistic wrist motion, she wore a custom volar wrist orthosis in addition to working on gentle passive wrist extension exercises. The orthosis prevented the maladapted wrist flexion by supporting the wrist in extension when she flexed her fingers, thus facilitating motor re-learning for synergistic wrist extension. See Figure 4. As Debbie gained passive wrist extension her orthosis was remolded to position her in greater wrist extension until her wrist reached 45 degrees. She also began load bearing exercises that focused on keeping the wrist extended and the fingers flexed. See Figure 5.

Figure 4. Volar wrist orthosis supports wrist during finger flexion
Figure 5. Load bearing into wrist extension with fingers flexed

Strengthening the Wrist Extensors

Debbie habitually substituted her extrinsic finger extensors for active wrist extension and was asked to focus on tenodesis: finger flexion when extending the wrist. She worked on isometric finger flexion and active wrist extension exercises while the fingers were held in gentle flexion during paraffin wax treatments. See Figure 6. When she was able to perform these active motions correctly, Debbie progressed to resisted wrist extension by pulling against resistive bands while holding a cylindrical object. See Figure 7.

Figure 6: Isometric finger flexion and wrist extension exercises during paraffin treatment
Figure 7: Resisted wrist extension while holding cylinder

Scar Hypersensitivity

CMMS is most often employed to improve finger range of motion while reducing edema and pain. After casting, Debbie continued with some residual scar hypersensitivity which she reported as tightness in her palm due to adherence. These symptoms were treated with approaches described in the previous Bracelab Clinical Pearls 52: Treating Linear Scars over Joints and 59: Tips for Keeping the Hand-Mind Connection.


Debbie’s case illustrates the importance of prolonged cast wear with slow weaning when using the CMMS treatment technique. There must be enough time in the cast to allow effective motor cortex repatterning to occur so long-term functional improvement can be retained.


1. https://bracelab.com/media/magefan_blog/PDFs/The-Stiff-Hand.pdf


Download Clinical Pearl No. 66, Regaining Synergistic Wrist Extension after Ending CMMS Too Early, February 2021

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Disclaimer: BraceLab Clinical Pearls are intended to be an informal sharing of practical clinical ideas; not formal evidence-based conclusions of fact.

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