Muscle strength is a determinant of bone mineral content in the hemiparetic upper extremity: Implications for stroke rehabilitation

Abstract

Individuals with stroke have a high incidence of bone fractures and approximately 30% of these fractures occur in the upper extremity. The high risk of falls and the decline in bone and muscle health make the chronic stroke population particularly prone to upper extremity fractures. This was the first study to investigate the bone mineral content (BMC), bone mineral density (BMD) and soft tissue composition of the upper extremities and their relationship to stroke-related impairments in ambulatory individuals with chronic stroke (onset >1 year). Dual-energy X-ray absorptiometry (DXA) was used to acquire total body scans on 56 (22 women) communitydwelling individuals (≥50 years of age) with chronic stroke. BMC (g) and BMD (g/cm 2 ), lean mass (g) and fat mass (g) for each arm were derived from the total body scans. The paretic upper extremity was evaluated for muscle strength (hand-held dynamometry), spasticity (Modified Ashworth Scale), impairment of motor function (Fugl-Meyer Motor Assessment) and amount of use of the paretic arm in daily activities (Motor Activity Log). Results showed that the paretic arm had significantly lower BMC (13.8%, p<0.001), BMD (4.5%, p<0.001) and lean mass (9.0%, p<0.001) but higher fat mass (6.3%, p=0.028) than the non-paretic arm. Multiple regression analysis showed that lean mass in the paretic arm, height and muscle strength were significant predictors (R 2 =0.810, p<0.001) of the paretic arm BMC. Height, muscle strength and gender were significant predictors (R 2 =0.822, p<0.001) of lean mass in the paretic arm. These results highlight the potential of muscle strengthening to promote bone health of the paretic arm in individuals with chronic stroke.

Balance, falls, and bone health: Role of exercise in reducing fracture risk after stroke

“…First, BMD in the paretic limbs is consistently lower than in the nonparetic limbs (by ≤20%) [38,40,[50][51][52][53][54]. The magnitude of the side-to-side difference found in individuals with stroke is much higher than that found between the dominant and nondominant sides in nondisabled older individuals (<1.5%) [55], which suggests a pronounced effect of hemiparesis on bone loss.…”

“…Following a stroke, individuals can have a multitude of impairments that result in compromised functional status, low physical activity, reduced use of the paretic arm and leg, and consequently bone loss overall that is greater on the paretic side. In persons with stroke, BMD on the paretic side has been correlated with muscle strength [38][39], muscle atrophy [38,40], degree of motor recovery [41][42][43][44], cardiovascular fitness [40], ability to perform functional activities [42,[44][45], walking ability [46], weight-bearing ability [47], and amount of skeletal loading [48]. The nonparetic side may also sustain a certain degree of bone loss that is less pronounced when compared with the paretic side [46][47]49].…”

“…First, muscle weakness and atrophy on the paretic side are common [38,40,100]. Muscle weakness and lean mass have a strong relationship with BMD in this group [38][39][40], just as in other populations [101][102].…”

Hand Bone Mineral Density in Hemiplegia and Their Clinical Corelation

“…Çalışmaya alınmada başlıca kriterler; tek taraflı ve ilk kez inme geçirilmiş olması, el ve el bileği başta olmak üzere üst ekstremitede kırık öyküsünün bulunmamasıdır (15). Hastalardan kemik metabolizmasını etkileyebilecek renal, hepatik veya tiroid fonksiyon bozukluğu olanlar, distal radiusta osteosentetik materyal bulunanlar, KMY'yi asimetrik etkileyebilecek osteosarkom, osteomiyelit gibi hastalıkları olanlar ya da kortikosteroid, tiroid hormon replasman tedavisi, antikonvülzanlar gibi bazı kemik mineral metabolizmasını değiştiren ilaçları kullananlar, herhangi bir romatolojik, ortopedik, travmatik ya da konjenital üst ekstremite ve el anomalisi olanlar çalışmaya dahil edilmemiştir.…”

“…Ayrıca hemiplejik hastalarda, alt ekstremitede KMY kaybı ve kalça kırıkları ile ilgili çok sayıda çalışma ve derleme bulunmasına rağmen (10)(11)(12); motor kaybın genellikle daha ciddi düzeyde seyrettiği üst ekstremitede (13)(14)(15) ve özellikle de elde KMY kaybının araştırıldığı çalışmaların sayısı oldukça azdır.…”