Study on the correlation between bone cement porosity and early stage prosthesis migration after cemented total hip replacement surgery

Abstract

[目的]比較全髖關節置換術后早期新型生物活性骨水泥即含鍶羥基磷灰石骨水泥(Sr-HA)與傳統的聚甲基丙烯酸甲酯骨水泥(PMMA)對假體固定的效果。[方法]從2008年5月2009年12月在香港瑪麗醫院行全髖關節置換術的9例(10膝)患者隨機分為觀察組和對照組,分別使用Sr-HA骨水泥與PMMA骨水泥固定股骨柄,于術后1周、3個月、6個月及12個月隨訪使用放射立體照相測量分析技術(RSA)測量股骨柄相對于股骨的位移,記錄Harris髖關節評分,并于實驗室使用顯微CT掃描測量兩種骨水泥的孔隙率進行比較。[結果]所有患者手術經過順利,無血管神經損傷、肺栓塞等并發癥。RSA結果顯示Sr-HA組有3例假體的下沉均超過1 mm,而PMMA組假體的下沉全部在1 mm以內。兩組患者的Harris髖關節評分在術后均有明顯改善。顯微CT掃描結果顯示Sr-HA骨水泥的孔隙率高于PMMA骨水泥,兩者之間差異有統計學意義(P<0.01)。[結論]兩組患者術后均無明顯臨床癥狀,含鍶羥基磷灰石骨水泥相對較高的孔隙率可能是導致全髖關節置換術后早期假體位移的原因。 [Objective]To compare cemented prosthesis stability fixed between bioactive bone cement,the strontium containing hydroxyapatite(Sr-HA) and conventional polymethyl methacrylate(PMMA) bone cement at the early stage after total hip replacement(THR) surgery. [Methods]Nine patients with ten knees received THR in Hong Kong Queen Mary Hospital during May 2008 to December 2009.They were randomly divided into experimental and control groups(5 knees in each group),receiving cemented THR with Sr-HA and PMMA bone cement respectively. Prosthesis migration was measured with radiostereometric analysis ( RSA) technique at 1 week，3 months, 6 months and 12 months after surgery. Meanwhile, Harris hip score ( HHS) was also taken. Additionally, cement porosity was scanned and analyzed with Micro - CT for both cements. ［Results］ None of nerve, vesse 1 injury or pulmonary embolism was observed. The migration of 3 prostheses in Sr - HA group exceeded 1 mm, while all prosthesis in in PMMA group migrated within 1 mm. The HHS improved significantly in all patients. Micro - CT scan revealed that cement porosity in Sr - HA group was significantly higher than in PMMA group ( p ＜ 0. 01) . ［Conclusion］Significant complication was not observed in all patients. The relative higher prosthesis migration of Sr- HA group at early stage after THR surgery was probably due to higher porosity of Sr-HA cement.