Mental stimulation strategies for enhancing postoperative recovery after knee replacement: a systematic review and meta-analysis

BACKGROUND: Rehabilitation following knee replacement typically includes joint mobilization, active and functional exercises. Recent studies have explored combining mirror-neuron system stimulation techniques with traditional rehabilitation, yielding promising results. This systematic review assessed the comparative effectiveness of Conventional Physiotherapy (CPT) combined with Mental Stimulation Strategies (MSS) versus CPT alone in improving pain and functional outcomes after knee replacement. METHODS: We conducted a systematic review and meta-analysis of Randomized Controlled Trials (RCTs). Two authors independently searched PubMed, CENTRAL, and Web of Science databases for articles comparing MSS in addition to CPT to CPT alone after knee replacement. The same authors independently extracted data, applied the Cochrane Risk of Bias 2 (RoB 2.0), conducted meta-analyses, and applied the GRADE for the certainty of evidence. Primary outcomes included pain, quadriceps strength, and Range of Motion (ROM). Secondary outcomes included mobility and motor function. Subgroup analysis was performed for the outcome pain and pROM, categorizing studies according to the type of mental stimulation technique used. RESULTS: We included 12 RCTs (324 patients). Meta-analyses showed effects favoring MSS in addition to CPT over CPT alone both in pain reduction (mean difference [MD] 1.23 cm, 95% confidence interval [CI] 0.72-1.75; N.=9; low certainty of evidence) and in quadriceps strength improvement (standardized mean difference 0.61, 95% CI: 0.21-1.02; N.=6; low certainty of evidence). No significant improvements were found for pROM (MD=1.68°, 95% CI: -1.55-4.91; N.=6; very low certainty of evidence) and active extension ROM (MD=0.15°, 95% CI: -0.28-0.75; N.=4; very low certainty of evidence). Regarding secondary outcomes, meta-analyses showed significant improvements in both mobility and motor function. Subgroup analysis revealed that both Action Observation Training and Motor Imagery, in addition to CPT, provided greater benefits for the outcome pain when compared to CPT alone. In contrast, neither technique appeared to offer additional benefits for pROM. CONCLUSIONS: The systematic review with meta-analysis showed a statistically significant benefit of MSS over CPT in motor and functional outcomes; however, the effect did not reach the minimal clinically important difference (MCID) for any studied outcome and, given the low certainty of evidence, warrants cautious interpretation and highlights the need for further studies.