Konan Sujith, Duncan Clive P, Masri Bassam S, Garbuz Donald S
Department of Orthopaedics, Vancouver General Hospital, University of British Columbia, JP North 3rd Floor, Room 3114, 910 West 10th Avenue, Vancouver, BC, V5Z 4E3, Canada.
Clin Orthop Relat Res. 2017 Feb;475(2):433-441. doi: 10.1007/s11999-016-4981-2.
The risk of early revision because of pseudotumors in patients who have undergone large-head metal-on-metal (MoM) total hip arthroplasty (THA) is well documented. However, the natural history of asymptomatic pseudotumors or of MoM articulations without pseudotumors is less well understood. The aim of our study was to investigate the natural history of primary MoM THA at mid-term followup.
QUESTIONS/PURPOSES: The purposes of this study were: (1) Did previously detected pseudotumors persist or worsen in asymptomatic patients at mid-term followup; and if so, did any of them require revision THA? (2) Did new pseudotumors form in asymptomatic patients at mid-term followup? (3) What happened to serum trace metal ions at mid-term followup? (4) Were postoperative patient-reported outcome measures (PROMs) maintained at mid-term followup?
Seventy-one patients who underwent a MoM THA using a Metasul LDH implant with a Durom acetabular cup and an M/L Taper stem between September 2005 and October 2008 were reviewed. All patients for this study were part of two previously published studies from our early followup. Data from the previous studies were used for comparison only. Two of the 71 patients (2.8%) were lost to followup. The mean age at operation was 56 years (range, 34-68 years). There were 24 female patients. All patients had serum trace metal ions testing, ultrasound imaging, and PROMs at a mean 3.5 years (early followup) after the index operation (range, 3-5 years) and delayed followup at a mean 7 years (range, 6.5-9 years). The indication to undertake revision THA was based on clinical evaluation and not solely on the investigation results.
Twenty-three of 71 patients (32%) had a positive ultrasound scan for pseudotumor at early followup. Of these, eight patients underwent revision THA (11% of MoM THA or 35% of patients with an early positive ultrasound scan). The mean time between positive ultrasound scan and revision surgery was 13 months (range, 5-22 months). Of the remaining 15 patients with pseudotumor noted on early ultrasound, 12 had persistent pseudotumor, two resolved, and one was lost to followup. Six patients (13%) with a normal ultrasound scan at early followup showed new ultrasound findings at delayed followup. Of these, four (8%) were conclusively diagnosed as pseudotumor and one was revised. Serum trace metal ion increased at mid-term followup in the seven cases that showed an increase in volume of pseudotumor. Of the five patients in whom the volume of pseudotumor decreased on ultrasound at mid-term followup, three showed a decrease in serum trace ions levels, whereas two showed an increase. New-onset pseudotumors at mid-term followup was associated with an increase in serum trace metal ions at mid-term followup only in two of six cases. PROMs at mid-term followup of patients in this study remain high.
At mid-term followup, approximately 35% of patients who develop an early pseudotumor undergo revision arthroplasty, whereas the remaining are asymptomatic. The incidence of new-onset ultrasound findings suggestive of pseudotumors at mid- to long-term followup is approximately 8% and these require continued surveillance.
Level II, prognostic study.
大头金属对金属（MoM）全髋关节置换术（THA）患者因假瘤而早期翻修的风险已有充分记录。然而，无症状假瘤或无假瘤的MoM关节的自然病程尚不太清楚。我们研究的目的是在中期随访时调查初次MoM THA的自然病程。
问题/目的：本研究的目的是：（1）在中期随访时，先前检测到的假瘤在无症状患者中是否持续存在或恶化；如果是，其中是否有患者需要翻修THA？（2）在中期随访时，无症状患者中是否形成了新的假瘤？（3）中期随访时血清微量金属离子发生了什么变化？（4）术后患者报告的结局指标（PROMs）在中期随访时是否得以维持？
回顾了2005年9月至2008年10月期间使用Metasul LDH假体、Durom髋臼杯和M/L锥形柄进行MoM THA的71例患者。本研究的所有患者均为我们早期随访的两项先前发表研究的一部分。先前研究的数据仅用于比较。71例患者中有2例（2.8%）失访。手术时的平均年龄为56岁（范围34 - 68岁）。有24例女性患者。所有患者在初次手术后平均3.5年（早期随访，范围3 - 5年）时进行血清微量金属离子检测、超声成像和PROMs评估，并在平均7年（范围6.5 - 9年）时进行延迟随访。进行翻修THA的指征基于临床评估，而非仅基于检查结果。
71例患者中有23例（32%）在早期随访时超声检查发现假瘤阳性。其中，8例患者接受了翻修THA（占MoM THA的11%或早期超声检查阳性患者的35%）。超声检查阳性至翻修手术的平均时间为13个月（范围5 - 22个月）。早期超声检查发现有假瘤的其余15例患者中，12例假瘤持续存在，2例消失，1例失访。6例（13%）早期超声检查正常的患者在延迟随访时有新的超声检查结果。其中，4例（8%）最终被诊断为假瘤，1例接受了翻修。在中期随访时，7例假瘤体积增大的病例血清微量金属离子升高。在中期随访时超声检查假瘤体积减小的5例患者中，3例血清微量离子水平降低，而2例升高。中期随访时新发假瘤仅在6例中的2例与中期随访时血清微量金属离子升高有关。本研究中患者的中期随访PROMs仍然很高。
在中期随访时，约35%出现早期假瘤的患者接受了翻修关节成形术，而其余患者无症状。在中长期随访时提示假瘤的新发超声检查结果的发生率约为8%，这些需要持续监测。
二级，预后研究。
