Abstract
BackgroundAlthough most patients achieve favorable results following bipolar hip hemiarthroplasty (BHA), some experience rapid migration of the prosthesis. We retrospectively reviewed 18 patients with BHA that necessitated revision.MethodsWe examined soft tissues obtained from periprosthetic lesions. In total, 18 patients with pain and acetabular migration of the BHA prosthesis were included. The patients were divided into a polymorphonuclear leukocyte (PMN)-positive (≥5 PMNs per high-power field [HPF]) and PMN-negative (<5 PMNs/HPF) group.ResultsPathological findings showed that 11 patients were PMN-positive, which was indicative of infection. All patients in the PMN-positive group showed no polyethylene particles or foreign body giant cells, while all patients in the PMN-negative group showed polyethylene debris or foreign body giant cells (p < 0.001). BHA survival, C-reactive protein (CRP) levels, and the Japanese Orthopaedic Association (JOA) hip score were significantly different between the PMN-positive and PMN-negative group (p < 0.01). A BHA survival cut-off value of 3270 days was diagnostic for PMN positivity (sensitivity: 100 %; specificity: 100 %). The cut-off values for CRP and the JOA hip score were 0.43 mg/dl and 56 points, respectively. Four of 11 PMN-positive patients showed no clinical symptoms of infection (asymptomatic PMN-positive group). BHA survival, CRP levels, and JOA hip scores were significantly different between the asymptomatic PMN-positive and PMN-negative group (p < 0.05). A BHA survival cut-off of 3270 days was diagnostic for asymptomatic PMN positivity (sensitivity: 100 %; specificity: 100 %). The cut-off values for CRP and the JOA hip score were 0.43 mg/dl and 57 points, respectively.ConclusionOur findings suggest that some portion of rapid BHA prosthesis migration is caused by mild infection. Careful pathological examination should be performed to identify infection before removal of the BHA prosthesis in patients who develop migration within 9 years.
Highlights
Most patients achieve favorable results following bipolar hip hemiarthroplasty (BHA), some experience rapid migration of the prosthesis
Bipolar hip hemiarthroplasty (BHA) was developed to reduce both wear on the acetabular cartilage and acetabular migration, both of which frequently occurred with unipolar prostheses of the Moore and Thompson type [2,3,4]
These findings suggest that polyethylene particles caused aseptic migration of the BHA prosthesis in the polymorphonuclear leukocytes (PMNs)-negative groups and that migration of the BHA prosthesis in the PMN-positive group was caused by infection
Summary
Most patients achieve favorable results following bipolar hip hemiarthroplasty (BHA), some experience rapid migration of the prosthesis. BHA has achieved moderately successful results, revision surgery is needed when the BHA prosthesis migrates [5,6,7,8]. Because the clinical symptoms of periprosthetic joint infection (PJI) are not always reliable, diagnosis relies on a combination of blood tests, culture, and histological examination [9]. It has been reported that accumulation of polymorphonuclear leukocytes (PMNs) in periprosthetic tissue is highly reliable evidence for PJI [10]. We performed histopathological examinations and found ≥5 PMNs per high-power field (HPF) in the periprosthetic tissues from 11 of 18 patients who underwent BHA revisions due to acetabular migration of the prosthesis.
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