Bone Mineral Density and Biochemical Markers of Bone Turnover During the First Year of Injury in Patients with Spinal Cord Injury

BackgroundSpinal cord injury (SCI) is associated with bone mass loss that can be complicated by fractures, which result in further disabilities for patients. After a SCI, the body starts losing large amounts of calcium and other minerals in the urine (demineralisation). This study aimed to assess the changes in bone mineral density (BMD) during the 1st year of acute SCI in patients with neurological deficit.MethodsA total of 95 patients with acute SCI and neurological deficit were evaluated in this prospective study. Haematological investigations such as evaluation of serum calcium, serum phosphate, serum creatinine, and serum alkaline phosphatase (ALP) were carried out. Urinary investigations such as 24-hour urinary creatinine level and excretion of calcium and phosphate in the urine were measured. BMD was measured using dual-energy X-ray absorptiometry scan with Hologic QDR 2000 scanner (Explorer). All of the aforementioned parameters were measured again at 3, 6, and 12 months.ResultsSerum ALP at 1-year follow up was significantly raised (p < 0.05). The BMD at 1-year follow up had statistically significant lower values than the initial BMD at the hip (p < 0.05), proximal tibia (p < 0.00l), and distal tibial epiphysis (p < 0.001). The BMD in motor-complete SCI patients [American Spinal Injury Association (ASIA) grades A and B] had significant lower values than motor-incomplete SCI patients (ASIA C and D) at the hip (p < 0.05) and proximal tibial epiphysis (p < 0.05).ConclusionThere was a marked decrease in BMD in metaphyseal sites than below the neurological deficit level with maximum decrease at the proximal tibia during the 1st year of SCI. Although the markers of osteoblastic activity did not show much change, the decrease in BMD was influenced by the neurological recovery after SCI.

中文摘要背景脊髓創傷（SCI）引發骨質流失可併發骨折，使患者進一步喪失功能。脊髓創傷後，身體開始在尿液中丟失大量的鈣和其他礦物質（去礦物質化）。本研究旨在評估在第一年急性脊髓創傷伴隨神經功能缺損的骨質密度（BMD）之變化。方法在這前瞻性的研究中，評估了95個患有急性脊髓創傷伴隨神經功能障礙的病例。包括檢驗他們血清中的鈣、磷、肌酐和鹼性磷酸酵並測量24小時尿中排泄的肌酐、鈣和磷。使用Hologic公司的QDR 2000雙能X射線光子吸收測定（DEXA）掃描儀（探索者）測量BMD。並於第三、六和十二個月隨訪復查量度上述之所有參數。結果在一年的隨訪復查，血清鹼性磷酸酶顯著上升（p < 0.05），骨質密度比較起初的數值在髖關節（p < 0.05），脛骨近端（p < 0.001）和脛骨遠端骨骺（p < 0.001）處明顯較低。完全失去活動功能的SCI患者（美國脊髓創傷協會 ASIA: A级與B级）之BMD比較那些非完全失去活動功能的（ASIA: C级與D级），在髖關節（p < 0.05）和近端脛骨骨骺（p < 0.05 ）處的量度數值明顯較低。結論脊髓創傷後的第一年，在脊髓損傷以下的幹骺端，骨質密度（BMD）顯著下降，其在脛骨近端的減少為最多。雖然成骨細胞的活性指標沒有出現太大的變化，但神經功能的恢復卻影響BMD的數值。