Plantar loading forces while walking in a below-knee cast with an attached loadbearing frame

Area of Science:

• Orthopedics
• Biomechanics
• Medical Device Technology

Background:

• Assessing load distribution in foot and ankle injuries is crucial for effective treatment.
• The patella tendon-bearing (PTB) or Sarmiento cast is the current standard for offloading foot and ankle forces.
• Investigating novel casting methods like the Böhler Walker frame is essential for improving patient outcomes.

Purpose of the Study:

• To compare the effectiveness of a Böhler Walker frame attached to a below-knee cast against traditional casting methods in reducing foot loading forces.
• To determine if the Böhler Walker frame offers superior or equivalent load distribution compared to Sarmiento and standard below-knee casts during full weightbearing.

Main Methods:

• Force sensors (TekScan FlexiForce A201) were applied to the first and fifth metatarsal heads and the calcaneus of 14 healthy volunteers.
• Force measurements were recorded with no cast, a Sarmiento cast, a standard below-knee cast, and a below-knee cast with a Böhler Walker frame.
• Peak forces at key plantar foot locations were analyzed under full weightbearing conditions.

Main Results:

• The Böhler Walker frame significantly reduced peak force: 58.9% at the first metatarsal head, 73.1% at the fifth metatarsal head, and 32.2% at the calcaneus (all P < .0001).
• In contrast, the Sarmiento cast showed minimal impact, with an 8.6% reduction at the first metatarsal head (P = .39) and a 4.4% reduction at the fifth metatarsal head (P = .87), while increasing calcaneal force by 5.9% (P = .54).
• These findings indicate a substantial difference in load reduction between the Böhler Walker frame and the Sarmiento cast.

Conclusions:

• A Böhler Walker frame integrated with a below-knee cast significantly decreases weight transfer through the foot compared to Sarmiento or standard below-knee casts.
• This enhanced force reduction may facilitate safer early weightbearing for various foot and ankle pathologies, potentially reducing immobility-related complications.
• The study highlights the potential clinical relevance of the Böhler Walker frame in managing foot and ankle conditions, improving patient recovery and reducing morbidity.