Periprosthetic femoral fractures (PFFs) remain a major concern following cementless total hip arthroplasty (THA). This study aimed to evaluate the association between different types of cementless tapered stems and the risk of postoperative PFF. A retrospective review of primary THAs performed at a single center from January 2011 to December 2018 included 3,315 hips (2,326 patients). Cementless stems were classified according to their design geometry using the system proposed by Radaelli et al. The incidence of PFF was compared between flat taper porous-coated stems (type A), rectangular taper grit-blasted stems (type B1), and quadrangular taper hydroxyapatite-coated stems (type B2). Multivariate regression analyses were performed to identify independent factors related to PFF. The mean follow-up duration was 61 months (range, 12‒139 months). Overall, 45 (1.4%) postoperative PFFs occurred. The incidence of PFF was significantly higher in type B1 stems than in type A and type B2 stems (1.8 vs. 0.7 vs. 0.7%; P=0.022). Additionally, more surgical treatments (1.7 vs. 0.5 vs. 0.7%; P=0.013) and femoral revisions (1.2 vs. 0.2 vs. 0%; P=0.004) were required for PFF in type B1 stems. After controlling for confounding variables, older age (P<0.001), diagnosis of hip fracture (P<0.001), and use of type B1 stems (P=0.001) were significant factors associated with PFF. Type B1 rectangular taper stems were found to have higher risks for postoperative PFF and PFF requiring surgical management than type A and type B2 stems in THA. Femoral stem geometry should be considered when planning for cementless THA in elderly patients with compromised bone quality.
Osteochondral (OC) defects of the knee are associated with pain and significant limitation of activity. Studies have demonstrated the therapeutic efficacy of mesenchymal stem cell (MSC) therapies in treating osteochondral defects. There is increasing evidence that the efficacy of MSC therapies may be a result of the paracrine secretion, particularly exosomes. Here, we examine the effects of MSC exosomes in combination with Hyaluronic Acid (HA) as an injectable therapy on functional osteochondral regeneration in a rabbit osteochondral defect model. Exosomes were purified from human MSC conditioned medium by size fractionation. A circular osteochondral defect of 4.5 mm diameter and 2.5 mm depth was surgically created in the trochlear grooves of 16 rabbit knees. Thereafter, eight knees received three weekly injections of 200 µg of exosomes in one ml of 3% HA, and the remaining eight knees received three weekly injections of one ml of 3% HA only. The rabbits were sacrificed at six weeks. Analyses were performed by macroscopic and histological assessments, and functional competence was analysed via Young Modulus calculation at five different points (central, superior, inferior, medial and lateral) of the repaired osteochondral defect site. MSC exosomes displayed a modal size of 100 nm and expressed exosome markers (CD81, TSG101 and ALIX). When compared to HA alone, MSC exosomes in combination with HA showed significantly better repair histologically and biomechanically. The Young Modulus was higher in 4 out of the 5 points. In the central region, the Young Modulus of MSC exosome and HA combination therapy was significantly higher: 5.42 MPa [SD=1.19, 95% CI: 3.93–6.90] when compared to HA alone: 2.87 MPa [SD=2.10, 95% CI: 0.26–5.49], p < 0 .05. The overall mean peripheral region was also significantly higher in the MSC exosome and HA combination therapy group: 5.87 MPa [SD=1.19, 95% CI: 4.40–7.35] when compared to HA alone: 2.70 MPa [SD=1.62, 95% CI: 0.79–4.71], p < 0 .05. The inferior region showed a significantly higher Young Modulus in the combination therapy: 7.34 MPa [SD=2.14, 95% CI: 4.68–10] compared to HA alone: 2.92 MPa [SD=0.98, 95% CI: 0.21–5.63], p < 0.05. The superior region showed a significantly higher Young Modulus in the combination therapy: 7.31 MPa [SD=3.29, 95% CI: 3.22–11.39] compared to HA alone: 3.59 MPa [SD=2.55, 95% CI: 0.42–6.76], p < 0.05. The lateral region showed a significantly higher Young Modulus in the combination therapy: 8.05 MPa [SD=2.06, 95% CI: 5.49–10.61] compared to HA alone: 3.56 MPa [SD=2.01, 95% CI: 1.06–6.06], p < 0.05. The medial region showed a higher Young Modulus in the combination therapy: 6.68 MPa [SD=1.48, 95% CI: 4.85–8.51] compared to HA alone: 3.45 MPa [SD=3.01, 95% CI: −0.29–7.19], but was not statistically significant. No adverse tissue reaction was observed in all the immunocompetent animals treated with MSC exosomes. Three weekly injections of MSC exosomes in combination with HA therapy results in a more functional osteochondral regeneration as compared to HA alone.
In recent years, there has been an increase in hip joint replacement surgery using short bone-preserving femoral stem. However, there are very limited data on postoperative periprosthetic fractures after cementless fixation of these stem although the periprosthetic fracture is becoming a major concern following hip replacement surgery. The purpose of this study is to determine incidence of postoperative periprosthetic femoral fractures following hip arthroplasty using bone preserving short stem in a large multi-center series. We retrospectively reviewed 897 patients (1089 hips) who underwent primary total hip arthroplasty (THA) or bipolar hemiarthroplasty (BHA) during the same interval (2011–2016) in which any other cementless, short bone-preserving femoral stem was used at 7 institutions. During the study, 1008 THAs were performed and 81 BHAs were performed using 4 different short femoral prostheses. Average age was 57.4 years (range, 18 – 97 years) with male ratio of 49.7% (541/1089). Postoperative mean follow-up period was 1.9 years (range, 0.2 – 7.9 years).Introduction
Materials & Methods
The fourth generation ceramic, in which zirconia is incorporated into the alumina matrix, was developed to reduce the risk of ceramic fractures. The purpose of this study was to evaluate the survivorship, clinical and radiographic results, and bearing-related failures associated with total hip arthroplasty using zirconia-toughened alumina ceramic-on-ceramic bearings over a minimum follow-up of 5 years. We retrospectively analysed 135 patients (151 hips) who underwent cementless total hip arthroplasty using zirconia-toughened alumina ceramic-on-ceramic bearings. There were 58 men and 77 women with mean age of 55.9 years (range, 20 to 82 years) at index surgery. Acetabular and femoral components were cementless in all hips. A 36 mm head was used in 81 of 151 hips and a 32 mm head was used in 70 hips with smaller acetabular shells. The mean duration of follow-up was 6.1 years (range, 5 to 6.8 years).Purpose
Materials and methods
The use of tranexamic acid (TXA) in primary total hip arthroplasty (THA) is supported by many studies that confirm its efficacy for decreasing blood loss, but the comparison between topical intra-articular (IA) and intra-venous (IV) is unclear, especially combined with chemical prophylaxis. The purpose of this study is to verify non-inferior efficacy of topical IA TXA compared with IV TXA in primary THA. A single center, randomized, controlled clinical trial was performed to compare topical IA TXA (2 g of TXA in 100 cc of normal saline) with two IV doses of TXA (1 g dose before surgery and another 1 g dose 3 hours later) on blood loss. The primary outcome was total blood loss as calculated from the difference between the preoperative hemoglobin (Hb) and the lowest postoperative Hb. The secondary outcome included drained blood loss, transfusion volume, and thromboembolic events. The sample size of 112 patients was calculated to give a statistical power of 99% for demonstrating inferiority. Fifty-six patients each was assigned to receive topical IA TXA (IA group) and IV TXA (IV group). There were no significant differences in demographics and preoperative laboratory values between the two groups. Non-inferiority was estimated by comparing the confidence interval with a delta of 10%. All subjects took oral direct factor Xa inhibitor to prevent venous thromboembolism included during 2 weeks after surgery.Introduction
Methods & Methods
As the proximal femoral bone is generally compromised in failed total hip arthroplasty, achievement of solid fixation with a new component can be technically demanding. Clinical studies have demonstrated good medium-term results after revision total hip arthroplasty using modular fluted and tapered distal fixation stems, but, to our knowledge, long-term outcomes have been rarely reported in the literature. The purpose of this study was to report the minimum ten-year results of revision total hip arthroplasty using a modular fluted and tapered distal fixation stem. We analyzed 40 revision THAs performed in using a modular fluted and tapered distal fixation stem (Fig. 1) between December 1998 and February 2004. There were 11 men (12 hips) and 28 women (28 hips) with a mean age of 59 years (range, 38 to 79 years) at the time of revision THA. According to the Paprosky classification of femoral defects, 5 were Type II, 24 were Type IIIA, and 11 were Type IIIB. An extended trochanteric osteotomy was carried out in 21 (52%) of the 40 hips. Patients were followed for a mean of 11.7 years (range, 10 to 15 years).Introduction
Materials & Methods
Patients with osteonecrosis of the femoral head are typically younger, more active, and often require high rates of revision following primary total hip arthroplasty. However, outcomes of revision hip arthroplasty in this patient population have been rarely reported in the literature. The purpose of this study was to report the intermediate-term clinical and radiographic outcomes of revision hip arthroplasty in patients with osteonecrosis of the femoral head. Between November 1994 and December 2009, 187 revision hip arthoplasty were performed in 137 patients who had a diagnosis of osteonecrosis of the femoral head. Exclusion criteria included infection, recurrent instability, isolated polyethylene liner exchange, and inadequate follow-up (less than 3 years). The final study cohort of this retrospective review consisted of 72 patients (75 hips) with a mean age of 53.3 years (range, 34 to 76). Components used for the acetabular revision included a cementless porous-coated cup in 58 hips and an acetabular cage in 2 hips. Components used for the femoral revision included a fully grit-blasted tapered stem in 30 hips and a proximally porous-coated modular stem in 9 hips. The mean duration of follow-up was 7 years (range, 3 to 17).Introduction
Materials & Methods
Modern ceramic-on-ceramic bearings have become attractive alternatives to conventional polyethylene due to their low wear and minimal particle production. However, ceramic-on-ceramic implants have been associated with ceramic fracture and squeaking. To address these issues, large ceramic heads with a titanium-alloy sleeve have been introduced although limited data are available on their clinical outcomes. The purpose of this study was to report the midterm results of primary total hip arthroplasty using a 32mm with a titanium-alloy sleeve. We reviewed 245 patients who had 274 total hip arthroplasties with a 32 mm ceramic head with a titanium-alloy sleeve and had been followed for more than 5 years (average, 6.5 years; range, 5–9 years). The mean patient age at the time of surgery was 55.1 years (range, 16–82 years). All operations were performed at a single center. All of the ceramic implants were hot isostatic pressed, laser-marked, proof-tested third-generation alumina (Fig. 1). We determined the implant survival, Harris hip scores, incidence of ceramic fracture or noisy hips, and presence of osteolysis.Introduction
Materials & Methods
Highly cross-linked polyethylene has been introduced to decrease osteolysis secondary to polyethylene wear debris generation, but there are few long-term data on revision total hip arthroplasty using highly cross-linked polyethylene liners. The purpose of this study was to report the long-term radiographic and clinical outcomes of a highly cross-linked polyethylene liner in revision total hip arthroplasty. We analyzed 63 revision total hip arthoplasties that were performed in 63 patients using a highly cross-linked polyethylene liner between April 2000 and February 2005. Of these, nine died and four were lost to follow-up before the end of the 10-year evaluation. Thus, the final study cohort consisted of 50 patients (50 hips). There were 26 males and 24 females with a mean age at time of revision total hip arthoplasty of 53 years (range, 27–75 years). Mean duration of follow-up was 11 years (range, 10–14 years).Introduction
Materials & Methods
Cementless grit-blasted tapered-wedge titanium femoral stems are being used with increasing frequency in hip arthroplasty because of excellent long-term outcomes. However, periprosthetic femur fracture is a potentially worrisome phenomenon in these types of femoral stems. The aim of this study is to report the incidence of stem loosening in association with periprosthetic femur fractures following hip arthroplasty using cementless grit-blasted tapered-wedge stems. A total of 36 Vancouver Type B1 and B2 periprosthetic femur fractures following either hemiarthroplasty or total hip arthroplasty using cementless grit-blasted tapered-wedge titanium femoral stems (GB group) were identified from a retrospective review of the medical records at three participating academic institutions. The control group consisted of 21 Vancouver Type B1 and B2 periprosthetic femur fractures following either hemiarthroplasty or total hip arthroplasty using cementless proximal porous-coated femoral stems (PC group) at the same institutions during the same period of the study. All femoral stems included in this study had been a well-fixed state before the occurrence of periprosthetic femur fractures. All patients in both groups were treated surgically with either open reduction and internal fixation or femoral stem revision. Femoral stem stability was assessed by preoperative radiographs and was confirmed by intraoperative scrutinization. The incidence of stem loosening was compared between the groups.Introduction
Materials & Methods
Micro-arc oxidation (MAO) is an electrochemical method used to treat metal surfaces. It provides nanoporous pits, and thick oxide layers, and incorporates calcium and phosphorus into the coating layer of titanium alloy. This modification on the surface of titanium alloy by MAO coating would improve the ability of cementless stems to osseointegrate. In spite of these structural and chemical advantages, clinical study of total hip arthroplasty (THA) using MAO coated stem has not yet been reported. In this study, we evaluated the clinical and radiographic results associated with cementless grit-blasted tapered-wedge stems that were identical in geometry but differed with regard to surface treatment with or without MAO coating. We performed a retrospective review of 141 THAs using MAO coated stem for a minimum of 5 years and compared them to 219 THAs using the same geometry stem without MAO coating. A cementless Bencox femoral component (Corentec, Seoul, Korea) was used in all hips. It is made of titanium alloy with a straight, double wedged, tapered stem with a rectangular cross-section. Surface treatment was performed using grit blasting with a roughness of 5.5ųm that was available either with or without MAO coating. Clinical and radiographic evaluations were performed preoperatively and at 6 weeks, 3 months, 6 months, and 1 year postoperatively, and then annually.Introduction
Materials & Methods
The robot-assisted cementless total hip arthroplasty has theoretical advantages of providing better fit and mechanical stability of the stem. However, no previous study has been reported on a short stem implantation using surgical robot. We compared early clinical and radiographic results between robotic milling and manual rasping in short stem total hip arthroplasty. We designed a prospective randomized controlled trial to determine whether robot-assisted short stem total hip arthroplasty improves the implant position represented by stem alignment, leg length equality, and reduces the intraoperative and early postoperative complications. A total of 40 patients were enrolled with informed consents and randomly assigned to robotic milling group (20 hips) and manual rasping group (20 hips) by means of a computer-generated random number table. There were no statistically significant differences in the demographics of the patients between the two groupsIntroduction:
Materials & Methods:
The outcome of previous cemented total hip arthroplasty has been reported to be inferior in renal transplant patients because of poor bone stock resulting from long-term steroid use. Moreover, as renal transplant patients remain on immunosuppressant therapy for life, higher levels of overall morbidity must be considered. We evaluated the mid-term results of cementless total hip arthroplasty in renal transplant recipients with osteonecrosis of the femoral head, and compared those with age and sex matched osteonecrosis patients that had not undergone organ transplantation or been treated with long-term steroid. Between October 1997 and October 2008, 45 consecutive primary cementless total hip arthroplasties were performed in 30 patients with advanced osteonecrosis of the femoral head after renal transplantation. There were 18 males (27 hips) and 12 females (18 hips) of overall mean age 44 years (22 to 68). The clinical and radiographic results of cementless total hip arthroplasty in these 45 hips were compared with those of 96 sex and age-matched osteonecrotic hips of 72 patients that had not undergone organ transplantation or long-term steroid use. Patients were evaluated at surgery and at a mean of 7.2 years (range, 2–13 years) postoperatively.Introduction:
Materials & Methods:
Ceramic head with titanium-alloy sleeve offers a modular ceramic head solution for the damaged taper in revision total hip arthroplasty (THA). It can also be used in primary THA to reduce the risk of ceramic head fracture. The purpose of the present study was to report the intermediate-term outcomes of primary ceramic-on-ceramic THA with use of ceramic head with titanium-alloy sleeve. We evaluated 244 patients (271 hips) who had undergone primary ceramic-on-ceramic THA with use of BIOLOX® forte 32 mm ceramic head with titanium-alloy sleeve between November 2005 and August 2009. There were 158 males (175 hips) and 86 female (96 hips) patients with a mean age of 55.5 years. Clinical and radiographic evaluation was performed at a mean of 4.6 years (range, 2–7 years) postoperatively.Introduction:
Materials & Methods:
The management strategy regarding optimally addressing polyethylene wear with a well-fixed acetabular shell remains controversial. The purpose of the present study was to document outcomes of cementation of a highly cross-linked polyethylene (PE) liner into a well-fixed acetabular metal shell in 36 hips We identified 37 patients (39 hips) who had undergone revision THA by cementation of a highly cross-linked PE liner into a well-fixed metal shell between June 2004 and April 2009. Of these patients, one (1 hip) died before the end of the 3-year evaluation and another was lost to follow-up. Thus, the study cohort consisted of 35 patients (36 hips). There were 23 males (24 hips) and 12 female (12 hips) patients with a mean age at time of revision surgery of 57.6 years (range, 38–79 years). All operations were performed by a single surgeon using only one type of liner. Clinical and radiographic evaluation was performed at a mean of 6.1 years (range, 3–8 years) postoperatively.Introduction:
Materials & Methods:
As the proximal femoral bone is generally compromised in failed hip arthroplasty, achievement of solid fixation with a new component can be technically demanding. Recent studies have demonstrated good short-term clinical results after revision total hip arthroplasty using modular distal fixation stems, but, to our knowledge, none have included clinical follow-up of greater than 5 years. The purpose of this study was to report the clinical and radiographic outcomes assessed 5 to 10 years following revision total hip arthroplasty with a modular tapered distal fixation stem. We retrospectively evaluated 50 revision total hip arthroplasties performed using a modular tapered distal fixation stem Between December 1998 and November 2003. There were 15 men (16 hips) and 34 women (34 hips) with a mean age of 59 years (range, 36 to 80 years). The index operation was the first femoral revision for 46 hips, the second for 3 hips, and the fifth for 1 hip. According to the Paprosky classification, 5 femoral defects were Type II, 31 were Type IIIA, and 14 were Type IIIB. An extended trochanteric osteotomy was carried out in 24 (48%) of the 50 hips. Patients were followed both clinically and radiographically for a mean of 7.2 years. The mean Harris hip score improved from 54 points preoperatively to 94 points at the time of the latest follow-up. The mean stem subsidence was 1.5mm. Three stems subsided more than 5 mm, but all have stabilized in their new positions. During follow-up, a total of 4 hips required additional surgery. One hip had two-stage re-revision due to deep infection, one had liner and head exchange for alumina ceramic head fracture, and the other two underwent isolated cup re-revision because of aseptic cup loosening and recurrent dislocation, respectively. No repeat revision was performed due to aseptic loosening of the femoral component. Complications included 6% intraoperative fractures, 4% cortical perforations, and 4% dislocations. There were no stem fractures at the modular junction. The medium-term clinical results and mechanical stability obtained with this modular tapered distal fixation stem were excellent in these challenging revision situations with femoral bone defects.
A retrospective study focusing on long-term follow up of 28 patients with a malignant bone tumour in the distal femur was conducted. Patients with a mean age of 50 (18–90) were clinically and radiologically followed-up for a mean period of 64 months (7–144). Osteosarcoma was the most common primary bone tumour, occurring in 15 patients. The 5-year survival for all patients was 80,9%. At final follow-up, 19 patients were still alive and had a mean follow up of 74,6 months (7–137). Clinical evaluation was done with the MSTS questionnaire (mean score: 70,0 (26,7–93,3)) and the use of the TESS (mean score: 82,5 (45–99,2) and SF-36 (mean Physical Component Score (PCS): 46,6 (27,1–56,5), mean Mental Component Score (MCS): 53,7 (range 37,0–62,1) was introduced There were 12 complications: 5 aseptic loosenings, two deep prosthetic infections, two luxations, one prosthetic fracture and two fissures. Six failures were re-operated. An overall prosthetic survival at 5-years of 77,0 % was found. A total of eight (29%) prostheses were considered to have failed after a mean follow up of 27,4 months (0–97). Risk factors in failure of the prosthetics were: non HA-coated stem and top stem-ratio >
1.2. Not length of the endoprosthesis and base stem-ratio. The top-ratio had a mean value of 1,14 (1,00–1,52) and for the four patients with an aseptic loosening the mean top-ratio was 1,23 (1,12–1,51) which was significantly different (p<
0,05 Mann-Whitney U test). Our results suggest that of the MUTARS endoprosthesis has a good 5-year survival. The use with a HA coating is preferable. The use of a stem-cortex ratio (>
1.2) at the top of the prosthetic stem can be predictor for aseptic loosening. The addition of the TESS and SF-36 scores give more insight information in how patients undergo their disease: half do not feel disabled.
Limb-sparing surgery has become the preferred surgical treatment of malignant bone tumours of the knee. In patients with intra-articular extension of their tumour, extra-articular limb sparing surgery can prevent the knee from amputation. In a retrospective study between January 1985 and December 2007, we performed 34 extra-articular tumour resections of the knee-joint for a bone- or soft tissue tumour in the distal femur or proximal tibia with (suspect) intra-articular tumour extension into the knee on MRI. Contra-indications were extension of the tumour into the extensor mechanism and/or tumour involvement of the neurovascular bundle. Osteosarcoma (23/34) was the most common primary malignancy. Mean age was 36 years (17–70) and the mean follow up was 9 years (1–19). Patient survival rates at 5 years and 10 years are 78% and 58% respectively, mean patient survival was 47 months (8–211). In 12 (35%) patients, the primary implanted prosthesis failed during follow up. Prosthetic survival rates including minor revision surgery were 63% at 5 years and 36% at 10 years. Six (18%) patients had local recurrence of their malignancy, 5 of them in the popliteal fossa. Local recurrence was significantly correlated with marginal margins (P<
0.05). Fifteen patients had major complications (44%) mainly deep infection in proximal tibia resections and aseptic loosening in distal femur resections. Aseptic loosening was significantly correlated with non HA-coated stems (P<
0.05). Functional outcome scores according to MSTS (mean 81, (65–93)) and TESS (mean 85, (56–98)) of survivors are good. Our results suggest that extra-articular tumour resections of the knee-joint can provide a functional endoprosthesis and can be an alternative for primary amputation. However it is a technical demanding procedure with acceptable local recurrence and high complication rates in patients with, in general, poor survival.
Risk of impingement after total hip resurfacing arthroplasty may be great because femoral head-neck unit is preserved and there is little flexibility to adjust limb length and femoral offset, but this potentially worrisome phenomenon has been rarely reported. Impingement between femoral neck and acetabular cup was observed in a cohort of patients who underwent contemporary total hip resurfacing arthroplasty. We then questioned whether patient demographics, component features or suboptimal position of components would be risk factors for impingement. We reviewed a consecutive series of 51 patients (61 hips) who underwent contemporary total hip resurfacing arthroplasty. The mean age at the time of the index arthroplasty was 38 years (18 to 64). The most common diagnosis leading to the total hip resurfacing arthroplasty was osteonecrosis of the femoral head in 41 hips (67%). All the procedures were performed by single surgeon through an anterolateral approach. All the patients were assessed clinically and radiographically at a mean of 32 months (24 to 53) postoperatively. Femoro-acetabular cup impingement, defined as the presence of bony spur at the femoral neck corresponding to abutment site of the metallic cup, was observed in seven of the 61 hips (11.5%). Of these, five patients reported limitation of activities due to groin pain. The average postoperative Harris hip score of impingement hips was inferior to those of non-impingement hips (p = 0.004). No significant difference was detected between the impingement hips and non-impingement hips with regard to of patient demographics, component features and radiographic measurements including cup inclination, cup version, femoral component version, anterior femoral offset, stem-shaft angle, femoral offset and limb length discrepancy. Our multivariate analysis revealed that only acetabular cup uncoverage ratio had a significant association with femoro-acetabular cup impingement (p = 0.04, odds ratio 1.385 [95% CI, 1.014 – 1.891]). There was no aseptic loosening of components or femoral neck fracture. We found a high incidence of impingement between retained femoral neck and metallic acetabular cup after contemporary total hip resurfacing arthroplasty in association with an increased acetabular cup uncoverage ratio. As patients with femoro-acetabular cup impingement showed inferior clinical results, it is crucial to avoid excessive protrusion of acetabular cup beyond bony margin by proper selection of acetabular component size and appropriate positioning.
Metal-on-metal bearing was re-introduced with the aim of eliminating polyethylene wear and resulting complications of osteolysis and aseptic loosening in total hip arthroplasty (THA). However, authors of recent studies have reported periprosthetic osteolysis and aseptic failure following second-generation metal-on-metal THA. The purpose of this study is to report the results at a minimum of five years following cementless total hip arthroplasty with a contemporary metal-on-metal articulation. Our study included findings of histologic examination on periprosthetic tissues from revised hips and wear and roughness analysis of retrieved implants. A consecutive series of 158 cementless THAs that were performed in 154 patients using a contemporary metal-on-metal bearing were assessed at a mean of 6.5 years (5 to 8). Their mean age at surgery was 53 years (21 to 80). The patients were assessed clinically with use of the Harris hip score, and the hips were assessed radiographically. Histological analysis was performed on specimens retrieved from the revised hips, and wear and roughness measurements were made for the explanted prostheses. The average Harris hip score improved from 45 points preoperatively to 92 points at the final follow-up examination. There was no aseptic loosening of the femoral or acetabular components. One hip was revised because of recurrent dislocation and one was managed with two-stage re-implantation for deep infection. Thirteen hips (8%) had osteolysis; 11 had osteolysis localized within the greater trochanter and two had both femoral and ace-tabular osteolysis. Of these, five patients who had a persistent pain and osteolysis underwent revision operation for the consideration of bearing exchange to a ceramic-on-ceramic or ceramic-on-polyethylene combination. All these revised hips showed extensive synovial-like tissue hypertrophy and perivascular infiltration of lymphocytes on histological examinations. Annual volumetric wear rate measured on one retrieved femoral head was 1.04mm3/yr, and roughness measured on three retrieved femoral heads was consistently very low between 8nm and 117nm. After the revision surgery, all the patients noticed disappearance of pain as well as radiographic evidence of healing of the osteolytic lesion. Our mid-term follow-up of cementless THA using a contemporary metal-on-metal bearing revealed an unexpectedly high rate of periprosthetic osteolysis possibly in association with metal hypersensitivity. In patients with persistent hip pain and osteolysis after contemporary metal-on-metal THA, surgeons should consider an exchange of the articulation surface to a ceramic-on-ceramic or ceramic-on-polyethylene combination because they can be cured only after an elimination of the source of hypersensitivity reaction.
