Objectives

Metal-on-metal (MoM) hip resurfacing was introduced into clinical practice because it was perceived to be a better alternative to conventional total hip replacement for young and active patients. However, an increasing number of reports of complications have arisen focusing on design and orientation of the components, the generation of metallic wear particles and serum levels of metallic ions. The procedure introduced a combination of two elements: large-dimension components and hard abrasive particles of metal wear. The objective of our study was to investigate the theory that microseparation of the articular surfaces draws in a high volume of bursal fluid and its contents into the articulation, and at relocation under load would generate high pressures of fluid ejection, resulting in an abrasive water jet.

Introduction:. The C-Stem in its design as a triple tapered stem, is the logical development of the original Charnley flat-back polished stem. The concept, design and the surgical technique cater for a limited slip of the stem within the cement mantle transferring the load more proximally.

Method: Five thousand two hundred and thirty three primary procedures using a C-stem have been carried out since 1993. We reviewed all 621 cases that had their total hip arthroplasty before 1998.

Results:. Sixty nine patients (70 hips) had died and 106 hips had not reached a ten-year clinical and radiological follow-up and had not been revised. In 22 hips, the stem had been changed before the 10 year follow-up, with infection, dislocation and loosening of the cup being the reasons for revision. None of the stems were loose.

The remaining 423 hips had a mean follow-up of 11 years (range 10 – 15 years). There were 216 women and 173 men, and 34 patients had bilateral LFAs. The patients’ mean age at surgery was 53 years (range 16 – 83 years). Thirty eight hips had been revised at the time of review. The reasons for revision were infection in 5: dislocation in 2: loose cup in 28: wear in 2 and 1 for meralgia paresthetica where the stem was found to be well fixed. In 1 case which had not been revised there was radiological loosening of the stem in a patient with Gaucher’s disease.

Discussion: With only 1 stem radiologically loose and no revisions for stem loosening the clinical results are very encouraging and they support the concept of the Charnley cemented low friction arthroplasty, but place a demand on the understanding of the technique and its execution at surgery.

Background: Since Sir John Charnley introduced bio-clean air operating techniques such as the “body exhausting” system and a bio-clean air operating theatre to reduce the risk of infection 3), total hip replacement has become one of the safest and most successful procedures in orthopaedic surgery and has benefited numerous people suffering from arthritis all over the world. However, deep infection is still undoubtedly one of the most serious complications after total hip arthroplasty (THA). It is still controversial whether one or two stage revision should be indicated for deeply infected hip replacement.

Purpose: The aim of this study was to identify the influential factors in one stage revision THA for deep infection with a long-term follow-up.

Methods: One stage revision THA for deep infection was carried out in 273 joints on 262 patients by the senior author between 1974 and 2000. All infected hip replacements were primarily treated with one stage revision THA regardless of micro organisms at the authors’ unit as far as sufficient bone stock for socket fixation was available in the acetabulum. This study included 162 revisions in 154 patients for which a minimum follow-up of five years (range 5 to 28 years; average 12.3 years) had been done. Fifty-two cases (32.1 %) had had discharging sinus by the time of revision surgery for infection.

Results: One hundred and thirty eight (85.2 %) hips were free of infection at the time of the latest follow-up. Twenty cases (12.3 %) had reoperation for recurrent infection. Four hips (2.5 %) maintained their implants with the evidence of infection. Twenty-two cases (13.6 %) showed radiological loosening. Thirteen cases (8.0 %) were revised again for reasons other than infection (12 for aseptic loosening and one for dislocation). Bone stock did not have significant influence on infection control while it did affect mechanical outcome. The cement-bone interface was an affecting factor for not only the mechanical survival of implants but also the cure of infection. Neither discharging sinus nor gram-negative microorganism was considered as a contraindication.

Conclusion: This study presented the longest follow-up with a large number of cases in revision THA for deep infection. The results suggested that shielding medullary space with antibiotic-loaded cement was important for treatment of infected THA.

Factors influencing the results of revised cemented sockets with bone grafting have been studied in 249 cases.

Freeze-dried allografts in 77 and fresh frozen in 172 cases have been used. The average follow-up was 8 years 11 months for the freeze-dried group and 2 years 11 months for the fresh frozen cases. There were 13 postoperative dislocations, 20 TNU, 4 thromboembolic complications, 4 delayed wound healing and 2 intraoperative fractures of the acetabulum. There have been 11 re-revisions: 8 for aseptic loosening, 2 for dislocation and 1 for infection. Radiographic evidence of loosening was seen in another 38 cases.

The acetabular bone stock at the time of revision and initial stability of socket fixation had a significant influence on the outcome. Direction of socket migration before surgery appeared to predict risk of failure. The primary pathology, type of bone graft and grafting technique also had an effect.

We previously reported the result of 45 Charnley LFA’s with femoral head autograft for Developmental Dysplasia of the hip with a minimum follow-up of ten years.

After an average follow-up of eleven years there was no revision. One socket migrated and four sockets were fully demarcated.

To assess our long-term results we reviewed the clinical and radiological findings in the same group of patients that had been studied previously.

To date 5 patients died from causes unrelated to the hip replacement and were excluded from the final radiological analysis. 40 Charnley LFA’s have been followed-up regularly.

The average follow-up is now 17 years 1 month / range: 15–21 years/. Three sockets have been revised: two for aseptic loosening and one for infection. Radiographic assessment showed that three sockets migrated and four had full demarcation.

Demarcation at the cement-bone interface of the socket was rare in zone one but was common in zone two.

We concluded that sound fixation of the autograft and orientations of the acetabular component are essential. We recommend that solid bone graft should be combined with impaction bone grafting in dysplastic cases. We also observed that bone grafting at primary surgery gives better chances for component fixation at the time of revision.

Background: Dislocation after total hip replacement (THR) is a significant concern with the increased number of THR carried out all over the world, although there has been a substantial lack of information regarding revision THR for instability in literature.

Purpose: The purpose of this study was to evaluate the effectiveness of operative treatment for recurrent dislocation after THR.

Material and methods: One hundred and eleven cases were treated operatively for recurrent dislocation after THR by a senior author (BMW). Group A; 104 cases were operated with change of either or both of components, a socket and a stem. Twenty-two mm head was used in 90 cases (A-1), 32 mm head in twelve (A-2), and 36 mm head in two (A-3). Group B; only modular head was changed in one case. Group C; augmentation device was applied on a cup in six cases. The average follow-up period was 6.2 years (range, 1 to 21 years).

Results: Group A-1; twelve cases (13%) required further operations for instability (N=90). Group A-2; one case (8.3%) was converted to Girdle-Stone for recurrent dislocation (N=12). Group A-3; one of them was revised for periprosthetic fracture (N=2). Group B; the case survived at the follow-up of 3.3 years (N=1). Group C; two cases (33%) were revised for dislocation (N=6).

Conclusion: We reported the largest series of revision THR for recurrent dislocation by a single surgeon with a considerable length of follow-up periods. Revision THR with change of components was an effective treatment for recurrent dislocation after THR.

Hip prostheses that do not reproduce the patients’ preoperative femoral offset have been correlated with increased wear rate, instability, abductor weakness and reduced range of motion. We have reviewed the results of 54 primary low friction arthroplasties with low offset stem commonly called “¾ neck Charnley” in 49 patients (47 females and 2 males). There has been no publication in literature on the results of this stem. Mean age was 68 years (range 30 to 83). The operations were performed by one of us, (VR) as an orthopaedic trainee, with a mean follow up of 8.7 ± 2 years. The preoperative diagnosis was 40 OA, 8 protrusio, 2 DDH, 2 post-traumatic, 1 SUFE and 1 RA. The preoperative offset was 41.9 ± 7.1 mm (mean ± STD), weight 65 ± 8.4 kg, height 156.4 ± 8 cm.

At their latest review 3 cases had been revised for infection or recurrent instability with a survivorship of 93.5% using Kaplan Meyer’s analysis. None of the femoral or acetabular components were loose or at risk of loosening. 16 cups showed demarcation in 1 zone of ≤ 1mm, and 2 cups had a 2 mm demarcation in 2 zones that was not progressive. 7 stems had ≤ 1mm demarcation in 1 zone, and 5 stems at 2 zones. Condensation at the tip of the stem was noted in 2 hips. The linear wear rate was 0.2 ± 0.08mm/year. Using Pearson’s correlation coefficient with P< 0.05, no statistically significant correlation was found between the preoperative offset and the linear wear rate.

We believe that the surgeon should try to reproduce the patient’s femoral offset aiming for the best intra-operative soft tissue balance. The linear wear rate in this series is higher than previously reported in cases that survived for over 20 years from this unit. However, at this stage of analysis low offset Charnley stems produce good medium term results.

Since wear and loosening of the ultra high molecular weight polyethylene is the one factor limiting the life of the arthroplasty we set out to identify factors associated with either low wear 0.02 mm/year or less, or high wear 0.2 mm/year or more.

In a group of 1092 patients, 1434 Charnley low-friction arthroplasties 190 (13.2%) showed low wear while 149 (10.4%) showed high wear. We used Chi square test to assess the significance.

The characteristics of the low wear group were: female gender (p=0.042) Rheumatoid arthritis (p= 0.014), Charnley category “C” patients (p=0.03) and varus position of the stem (p=0.003) The use of acetabular cement pressurization (p=0.07) and medialization of the cup (p=0.07) approached significance.

In the high wear group there was a predominance of males (p=0.042) with primary arthritis (p=0.006) as the underlying hip pathology, and the stem in valgus position (p=0.023). Rim position of the cup was approaching significance (p=0.07). There was no statistical significance between the two groups for revision for aseptic stem loosening or stem fracture (p= 0.49). There was a highly significant difference (p< 0.0001) between the two groups for revision for wear and aseptic cup loosening: 5.3% against 40%.

Changes in the cup geometry are sufficient to explain the increasing incidence with depth of cup penetration. There is much to be gained from the use of low wearing ceramic – ultra high molecular weight combination. Tissue reaction to the plastic particles cannot be the cause of stem loosening.

Purpose: The purpose of this study was to assess preoperative bone stock and immediate postoperative cement-bone interface as factors affecting infection control and mechanical outcome after one stage revision total hip replacement (THR) for deep infection.

Material and methods: This study included 115 cases which satisfied following conditions; a) One stage revision THRs for deep infection were carried out by a single surgeon (BMW). b) Follow-up of more than five years was possible. c) Complete series of radiographs were available including preoperative, immediate postoperative and the latest follow-up ones. Preoperative bone stock was classified into four grades (Grade 0: No bone loss, Grade 1: Demarcation, Grade 2: Localized cavitation, Grade 3: Significant bone loss). Immediate postoperative cement-bone interface was also graded into four categories (Grade A: White-out, obscure interface, Grade B: Clear line, no measurable gap, Grade C: Gap> 1mm, Grade D< 1mm). These two factors were analysed in view of infection control and mechanical survival of implants after surgery.

Results: Preoperative bone stock did not show significant influence on infection control while it affected mechanical outcome. Immediate postoperative cement-bone interface was an affecting factor for not only mechanical survival of implants but cure of infection.

Conclusion: Preoperative bone stock and immediate postoperative cement-bone interface were assessed as influential factors in one stage revision THR for deep infection. There was a good chance of cure of infection even in cases with significant bone loss. Good cement fixation appeared to be important in view of infection control as well as mechanical survival of implants.

We report the result of 49 revisions for aseptic cup loosening using freeze-dried allografts.

We assessed the results according to the primary pathology, severity of bone loss, direction of socket migration before revision, method of bone grafting, socket position, graft incorporation and socket loosening.

Patient’s mean age at revision was 56 years 8 months. At a mean follow up of 7 years and 5 months four cups have been revised for aseptic loosening. Five sockets have migrated but remained stable while six showed full demarcation but have not migrated.

The other 34 remained stable and show radiographic evidence of graft incorporation.

Pyrexia in the post-operative setting has often been associated with a possible systemic or wound infection. We assessed whether there is any justification for our concern regarding post-operative pyrexia following hip arthroplasty and subsequent deep prosthetic infection.

Method:

Study 1

An assessment of the clinical outcome of 97 sequential patients who underwent 103 primary hip arthroplasty for primary osteoarthritis replacements. Daily temperature and systemic complications in the post-operative period were recorded. Clinical outcome was measured using an Oxford hip questionnaire.

Patients had a mean follow-up of 5.2 years (range 3.5–7.2years).

Study 2

A review of postoperative temperature records of 80 patients who had undergone primary total hip replacement. Thirty-one patients had required revision surgery at a mean time interval of 37.2 months (range 5–74 months) for confirmed deep prosthetic infection. The remaining Forty-nine patients were asymptomatic at a mean follow-up of 31.5 months.

Results:

Study 1

Post-operative pyrexia of 38 degrees Celsius was present in 51% of patient’s undergoing primary hip replacement in the first post-operative week but in 21.1% no etiological cause could be identified. Clinical outcome measured by an oxford hip questionnaire was not influenced by the post-operative temperature pattern.

Study 2

The mean peak temperature on the first post-operative day was significantly lower in patients with deep prosthetic infection then patients with a clinically normal outcome (p=0.01).

Conclusion: Post-operative pyrexia is clearly not uncommon following primary arthroplasty and its presence should not be regarded as detrimental. Pyrexia in the post-operative setting is a component of the acute phase response to trauma and study 2 demonstrates patients who develop a low-grade infection following arthroplasty may have diminished febrile response to surgical trauma.