Quadriceps and ankle weakness in inclusion body myositis: impact on descending balance control and rehabilitation strategies - a systematic review.

BACKGROUND

Inclusion Body Myositis (IBM), a progressive neuromuscular disorder, is characterized by quadriceps and ankle muscle weakness, leading to impaired balance control and increased fall risk during functional activities. Existing research highlights inconsistent evidence on fall risk reduction and a lack of standardized rehabilitation protocols, creating gaps in effective management. This systematic review aims to synthesize evidence on the impact of muscle weakness on balance and fall risk and evaluate rehabilitation strategies, including task-specific interventions, to improve functional outcomes in IBM patients.

METHODS

Following PRISMA guidelines, we conducted a systematic search of MEDLINE, Embase, and the Cochrane Library from inception to March 2025, using keywords such as "IBM," "muscle weakness," and "rehabilitation." Two reviewers independently screened studies assessing balance-related movement characteristics and rehabilitation strategies (e.g., resistance training, NMES, functional exercises). Quality and bias risk were assessed using Cochrane Risk of Bias 2 and ROBINS-I tools, with evidence certainty evaluated via the GRADE approach.

RESULTS

Of 1425 articles screened, 22 were selected for analysis. Quadriceps weakness, particularly in knee extensor eccentric control, impairs balance during sit-to-stand (STS), stand-to-sit (StandTS), walking, and stair activities, significantly increasing fall risk (moderate evidence). Ankle dorsiflexor weakness exacerbates this by causing foot drop and disrupting force transfer (moderate evidence). Rehabilitation interventions, including resistance training and NMES, show moderate evidence of improving muscle strength and functional capacity, while task-specific STS and StandTS training offer moderate promises for mobility.

CONCLUSIONS

Impaired knee extensor control, ankle dorsiflexor weakness, and poor leg joint coordination are key contributors to balance deficits and fall risk in IBM. Moderate evidence supports resistance training and STS/StandTS exercises for improving strength and functional capacity, though consistent fall risk reduction has not been established. Tailored, multifaceted rehabilitation, potentially including emerging strategies such as STS/StandTS, and walking, appears most promising. Large-scale, high-quality studies are needed to refine interventions, validate lower-evidence approaches, and establish standardized protocols to optimize safety and functional outcomes in IBM.