Introduction: Bone stock and cement-bone interface in revision total hip replacement (THR) for deep infection have never been investigated in the literature, while they are known to be important for aseptic loosening. 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 revision THR for deep infection. Methods: This study included 115 cases in which revision THR with antibiotic-loaded cement was operated for infected hip replacement by a single surgeon with minimal follow-up of five years (range 5–27 years). Preoperative bone stock was classified into four grades (Grade 0: No bone loss, Grade 1: Demarcation, Grade 2: Localized cavitation, Grade 3: Extensive bone loss). The 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 with regard to infection control and mechanical survival of implants after surgery. Results: Bone stock did not have significant influence on infection control while it affected mechanical outcome. The cement-bone interface was an affecting factor for not only the mechanical survival of implants but also the cure of infection. Discussion: There was a good chance of curing the infection even with extensive bone loss. Good cement fixation was an important factor with regard to infection control as well as the mechanical survival of implants. The results suggested that it might be important to shield the medullary space from the infected joint space with antibiotic-loaded cement

Aseptic loosening which may lead to osteolysis and massive loss of bone, remains the major cause of failure after total hip arthroplasty. Reconstruction of acetabular bone stock defects by means of bone grafting is mandatory to create a stable construct to support the cup, recreate anatomy, and restore lower limb length. Numerous classification systems for acetabular bone stock deficiencies have been recommended to date. The one proposed by the American Academy of Orthopedic Surgeons (AAOS) is the most comprehensive and most consistent. This system classifies acetabular defects into segmental (type 1), cavitary (type 2), combined segmental and cavitary (type 3), pelvic dissociation (type 4), and hip fusion (type 5). The aim of this study is to present a long term review of our experience with reconstruction of acetabular bone stock deficiencies in conjugation with revision hip arthroplasties using bone grafting, based on the AAOS classification system. Between 1987 and 1998, 88 revisions using bone grafting to reconstruct acetabular bone stock defects were performed. Of them 4 patients were classified as type 1, 47 as type 2, 29 – type 3, and 8 as type 4. The mean follow-up period was 8 years (range: 2–3 years). The mean Haris Hip Score improved from 35 points preoperatively to 75 postoperatively. All patients improved. The complications included nonunion in 5 cases, joint instability in 6 cases, graft lysis in one case, and neurologic injury in one case. Five cups were considered radiographicaly loose. One case was infected

Aims: Remaining bone stock at revision total hip arthroplasty (THA) determines the procedure and is related to outcome. This study was carried out to determine the radiological effect on bone stock of patients waiting for surgery. Methods: The hospital notes and AP pelvic radiographs of all (19) patients (22 hips) who underwent revision surgery for symptomatic aseptic loosening of a heterogeneous group of THAs over the last 2 years were obtained. The Hahnemann University Hospital (HUH) Classification and Staging System for Revision THA (a purely radiological classification that evaluates both the acetabular and the femoral bone stock, any component instability and sepsis and that correlates well with functional outcome) was used to evaluate bone stock on the initial clinic and the immediate preoperative radiographs. The effect of delay on the planned procedure was also recorded. Results: The average time delay for all patients was 57 weeks. 12/22 hips deteriorated radiologically by an average of 1.3 points (range 1–3) on the HUH Classification. In 7/12 it altered the procedure to be carried out. Conclusions: This preliminary study suggests that a delay to revision hip surgery is associated with a reduction in bone stock and hence potential functional outcome. It can also detrimentally affect the planned procedure. This study reinforces the need for minimal delay in symptomatic patients with aseptic loosening of THA

Stress shielding has been a well-recognised problem with uncemented femoral components resulting in proximal bone loss and dysfunction, but less attention has been paid to the preservation of acetabular bone stock. Uncemented acetabular components often demonstrate reduced bone density on plain radiographs in the mid-portion of the cup (zone 2), which may be due to the rigidity of the outer shell. This study compares the change in bone density around three different cups with varying moduli of elasticity at a minimum of 2 years. Our hypothesis was that less rigid cups would be associated with improved bone density and less stress shielding. This prospective randomised controlled trial compared the bone mineral content (BMC) adjacent to three different cups with marked differences in stiffness. Cup A was an all titanium shell, cup B was a titanium coated all polyethylene implant and cup C was a tantalum backed shell. All articulations used a 32mm ceramic femoral head. Cup B used polyethylene modified by treatment with vitamin E whereas cups A and C used a liner made of irradiated cross linked polyethylene. Five regions of interest (ROI) were established adjacent to the cup, regions 2, 3 and 4 where similar to the DeLee and Charnley regions 1, 2 and 3. Bone density was measured using IDXA preoperatively, postoperatively, 6 months, 1 and 2 years and compared for each ROI and implant. Precision measurements showed significant reliability. All areas showed a reduction in BMC following insertion of the acetabular cup. Bone loss was less in ROI 1 and 4 in the area of rim fit for all cups and the maximal bone loss was seen in ROI 2 and 3 at the dome of the cup. The more elastic cup (Cup B) produced the least bone loss in this area (p<0.05). Cup C produced the largest bone loss at ROI 2 (40%) which continued increasing at 2 years. Cup stiffness is related to bone loss adjacent to the acetabulum, presumably due to a similar process of stress shielding as seen in the femur. All cups produced similar changes at the periphery of the cup but the more elastic cup retained bone density beneath the cup which continued past 2 years. This improvement in bone quality is likely to be associated with better acetabular bone stock into the future and more reliable long term cup fixation

Background. Preservation of acetabular bone during primary total hip arthroplasty (THA) is important, because proper stability of cementless acetabular cup during primary THA depends largely on the amount of bone stock left after acetabular reaming. Eccentric or excessive acetabular reaming can cause soft tissue impingement, loosening, altered centre of rotation, bone-to-bone impingement, intra-operative periprosthetic fracture, and other complications. Furthermore, loss of bone stock during primary THA may adversely affect subsequent revision THA. Questions/Purposes. The purpose of this study was to compare preservation of acetabular bone stock between conventional THA (CTHA) vs. robotic-guided THA (RGTHA). We hypothesised that RGTHA would allow more precise reaming, leading to use of smaller cups and greater preservation of bone stock. Methods. Patients who received RGTHA were matched to a control group of patients who received CTHA, in terms of pre-operative native femoral head size (47.8mm – 48.1mm), age (mean 56.9), gender, BMI, and approach. Acetabular cup size relative to femoral head size was used as a surrogate for amount of bone resected. We compared the groups according to three measures describing the acetabular cup diameter (c) in relation to the femoral head diameter (f). These three measures were: (1) c-f, the difference between the cup diameter and femoral head diameter, (2) (c-f)/f, the same difference as a fraction of the femoral head diameter, and (3) (c∧3-f∧3)/f∧3, the same ratio expressed volumetrically. Results. A total of 57 matched pairs were included in each group. There were no significant differences between groups in terms of gender, age at surgery, or BMI. No differences in femoral head diameter or acetabular cup diameter were observed between groups (p > 0.05). However, measure (2) (c-f)/f and (3) (c∧3-f∧3)/f∧3 did differ significantly between the groups, with lower values in the RGTHA group (p < 0.02). Conclusion. RGTHA allowed for the use of smaller acetabular cups in relation to the patient's femoral head size, compared to CTHA. Using acetabular cup size relative to femoral head size as a surrogate measure of acetabular bone resection, these results indicate that greater preservation of bone stock using RGTHA compared to CTHA. This may reflect increased translational precision during the reaming process. However, further studies are needed to validate the relationship between acetabular cup size and loss of bone in THA

Aims: Aim of the work is evaluation of outcome after reconstruction of acetabular bone stock deþcit in revision hip alloplastics. Methods: Material consists 113 patients with septic and aseptic acetabulum loosening after THA, 31 (27,4%) with cementless and 82 (72,6%) with cemented THA. For evaluation of the functional outcome has been used AAOS scale. Loosening was evaluated on X-rays on behalf of symptoms described by De Lee and Charnley. Surgical tactic was based on Paprosky anatomical bone stock deþcit evaluation Results: Functional Harris hip scores after realloplastic showed improving in passive motion and lowering of pain complaints. There has been concluded full graft in osteointegration in cases with stabile placement of thick cancellous bone graft, with good contact between graft-bone interface and cup. Conclusions: Solid liophylized and milled cancellous bone grafts, used in reconstruction of acetabulum, can remodel and osteointegrate even in cemented technique if there is a sufþcient contact between acetabulum wall and graft. It is possible to obtain good long-term functional and radiological results with usage of operative technique based on remodeling of bone grafts

Introduction. Preoperative bone stock and cement-bone interface in revision total hip replacement (THR) for deep infection have never been investigated while they are both well known to be important for mechanical outcome after revision THR for aseptic loosening. Purpose. The purpose of this study was to assess pre-operative bone stock and immediate postoperative cement-bone interface as factors affecting infection control after one stage revision 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. b) Follow-up of more than five years was done. Preoperative bone stock was classified into four grades (Grade 0: No bone loss, Grade 1: Demarcation, Grade 2: Localized cavitation, Grade 3: Extensive 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 within 1mm, Grade D: Gap more than 1mm). These two factors were analyzed in view of infection control after surgery. Results. Preoperative bone stock did not show significant influence on infection control. Immediate postoperative cement-bone interface was an affecting factor for cure of infection. Conclusion. 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. The results suggested the importance of shielding of medullary space with antibiotic-loaded cement from infected joint space in revision THR for infection

Introduction: Total hip arthroplasty (THA) has proven to be a highly successful procedure, but with its increased use there are an increasing number of joints requiring revision. A number of those patients requiring revision present with a severe loss of femoral bone stock around the failed femoral hip implant, which makes conventional revision techniques difficult or impossible. Materials and Methods: We have followed a consecutive series of forty-nine revisions THA (45 patients), performed for severe femoral bone loss using anatomic specific proximal femoral allografts longer than five centimetres. The patients mean age at the time of the index surgery was 63 (32–86) years. The patients were followed for a mean of 8.4 (5.2–16.6) years, with a five-year minimum follow-up. Results: The mean Harris Hip Score improved from 42.9 points preoperatively to 76.9 points at the last review. Fort-three of the hips (88%) had a successful outcome. Kaplan-Meier survivorship analysis predicted 83% rate of survival at 17 years. Six hips (12.2%) were further revised: four for non-union and aseptic failure of the implant, one for infection, and one for host step-cut fracture. Radiographicly, junctional union was observed in 44 hips (90%). Asymptomatic non-union of the greater trochanter were noticed in three hips (6.1%). Moderate allograft resorption was observed in five hips (10.2%), none were full-thickness graft resorption. The complications include trochanteric escape in three hips, host step-cut fractures in two hips, and four dislocations. Conclusion: We conclude that the good medium-term results with the use of large anatomic-specific femoral allografts justify their continued use in cases of revision hip arthroplasty with severe bone stock loss

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

Background. Preservation of acetabular bone during primary total hip arthroplasty (THA) is important, because proper stability of cementless acetabular cup during primary THA depends largely on the amount of bone stock left after acetabular reaming. Eccentric or excessive acetabular reaming can cause soft tissue impingement, loosening, altered center of rotation, bone-to-bone impingement, intraoperative periprosthetic fracture, and other complications. Furthermore, loss of bone stock during primary THA may adversely affect subsequent revision THA. Questions/Purposes. We sought to compare the conventional THA (CTHA) approach to robotic-guided THA (RGTHA) to determine which of these techniques preserves more acetabular bone, as interpreted from the size of the acetabular component compared with the size of the native femoral head. Methods. Patients who received RGTHA were matched to a control group of patients who received CTHA, in terms of pre-operative native femoral head size (47.8mm – 48.1mm), age (mean 56.9), gender, BMI, and approach. Acetabular cup size relative to femoral head size was used as a surrogate for amount of bone resected. We compared the groups according to three measures describing the acetabular cup diameter (c) in relation to the femoral head diameter (f). These three measures were: (1) (c − f), the difference between the cup diameter and femoral head diameter, (2) (c − f) / f, the same difference as a fraction of the femoral head diameter, and (3) (c3 − f3) / f3, the same ratio expressed volumetrically. Results. A total of 57 matched pairs were included in each group. There were no significant differences between groups in terms of gender, age at surgery, or BMI. No differences in femoral head diameter or acetabular cup diameter were observed between groups (p > 0.05). However, measures (1)(c − f), (2)(c − f) / f, and (3)(c3 − f3) / f3 did differ significantly between the groups, with lower values in the RGTHA group (p < 0.02). Conclusion. RGTHA allowed for the use of smaller acetabular cups in relation to the patient's femoral head size, compared to CTHA. Using acetabular cup size relative to femoral head size as a surrogate measure of acetabular bone resection, these results indicate that greater preservation of bone stock using RGTHA compared to CTHA. This may reflect increased translational precision during the reaming process. However, further studies are needed to validate the relationship between acetabular cup size and loss of bone in THA

Introduction. Revision hip arthroplasty with massive proximal femoral bone loss remains challenging. Whilst several surgical techniques have been described, few have reported long term supporting data. A proximal femoral allograft (PFA) may be used to reconstitute bone stock in the multiply revised femur with segmental bone loss of greater than 8 cm. This study reports the outcome of largest case series of PFA used in revision hip arthroplasty. Methods. Data was prospectively collected from a consecutive series of 69 revision hip cases incorporating PFA and retrospective analyzed. Allografts of greater than 8 cm in length (average 14cm) implanted to replace deficient bone stock during revision hip surgery between 1984 and 2000 were included. The average age at surgery was 56 years (range 32–84) with a minimum follow up of 10 years and a mean of 15.8 years (range). Results. From the original cohort four patients had died with the original PFA, 21 (30.4%) patients required further surgery with 14 (20.3%) of these needing revisions of the femoral component. The mean time to femoral revision was 9.5 years and Kaplan-Meier survivorship analysis demonstrates a 79.9% PFA survivorship at 20 years. Discussion. Proximal femoral allograft affords long lasting reconstruction of the femoral component in revision hip surgery. We advocate PFA as an attractive option in the reconstruction of the hip in the presence of significant segmental bone loss in younger patients

Resurfacing arthroplasty is advantageous over conventional total hip arthroplasty in that femoral bone stock is preserved. However, there has been controversy over the preservation of acetabular bone stock in resurfacing arthroplasty, with the concern that it may result in excess reaming compared with total hip replacement. This is of concern as the prosthesis is primarily advocated in the young patient, who is likely to face future revision surgery. We prospectively identified a cohort of 68 patients with primary hip osteoarthritis undergoing conventional total hip arthroplasty. During surgery, the excised femoral head and neck diameter was measured, along with the diameter of the final acetabular reamer used to achieve a bed of bleeding cancellous bone. The measured neck diameter was then used to calculate the minimum possible resurfacing head and cup sizes, with corresponding final reamer sizes that could have been used in each patient without neck notching for both Birmingham Hip Resurfacing (BHR, Smith & Nephew, 3rd Generation) and Articular Surface replacement (ASR, De Puy, 4th Generation). Reaming diameter and volume was compared for all 3 groups. Mean reaming diameters for the THR, ASR and BHR groups were 51, 52 and 56mm respectively. Mean reaming volumes were 39, 40 and 47cc. There was a statistically significant difference between the THR and BHR groups for both reamed diameter and volume (p< 0.001). There was also a significant difference between the ASR and BHR groups for both reamed diameter and volume (p< 0.001). This difference was more pronounced with larger neck diameters. Our data shows that the BHR results in more ace-tabular bone loss compared to total hip replacement. An implant with a lower profile acetabular cup and a larger variety of sizes such as the ASR may allow better preservation of acetabular bone stock

Introduction and Aims: The purpose of this study was to assess pre-operative bone stock and immediate postoperative cement-bone interface as factors affecting infection control and mechanical outcome after one stage revision THR for deep infection. Method: This study included 115 cases which satisfied the following conditions: 1) One stage revision THR for deep infection was the primary intervention for infected hip replacement by a single surgeon (BMW) unless the bone stock was too poor for fixing implants; 2) follow-up of more than five years; 3) A complete series of radiographs was available for radiological study including pre-operative and immediate post-operative ones. Pre-operative bone stock was classified into four grades (Grade 0: No bone loss, Grade 1: Demarcation, Grade 2: Localised cavitation, Grade 3: Extensive bone loss). The immediate post-operative 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 with regard to infection control and the mechanical survival of implants after surgery. Results: 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. Conclusion: There was a good chance of curing the infection even with extensive bone loss. Good cement fixation was an important factor with regard to infection control, as well as the mechanical survival of implants. The results suggested that it was important to shield the medullary space from the infected joint space with antibiotic-loaded cement in revision THR for deep infection

We have followed a consecutive series of revision hip arthroplasties, performed for severe femoral bone loss using anatomic specific proximal femoral allografts. Forty-nine revision hip arthroplasties, using anatomic specific proximal femoral allografts longer than five centimetres were followed for a mean of 10.4 years. The mean preoperative HHS improved from 42.9 points to 76.9 points postoperatively. Six hips (12.2%) were further revised, four for non-union and aseptic failure of the implant (8.2%), one for infection (2%), and one for host step-cut fracture (2%). Junctional union was observed in 44 hips (90%). Three hips underwent re-attachment of the greater trochanter for trochanteric escape (6.1%). Asymptomatic non-union of the greater trochanter was noticed in three hips (6.1%). Moderate allograft resorption was observed in five hips (10.2%). Two fractures of the host step-cut occurred (4.1%). There were four dislocations (8.2%), two of them developed in conjunction with trochanteric escape. By definition of success as increase of HHS by 20 points or more, and no need for any subsequent re-operation related to the allograft and/or the implant, a 75.5% rate of success was found. Kaplan-Meier survivorship analysis predicted 73% rate of survival at 12 years, with the need for further revision of the allograft and/or implant as the end point. We conclude that the good medium-term results with the use of large anatomic- specific femoral allografts justify their continued use in cases of revision hip arthroplasty with severe bone stock loss

We have followed a consecutive series of forty-nine revision hip arthroplasties (45 patients), performed for severe femoral bone loss using anatomic specific proximal femoral allografts longer than five centimetres. The patients were followed for a mean of 10.4 years, with a five year minimum follow-up. The mean preoperative Harris Hip Score improved from 42.9 points to 76.9 points postoperatively, an average improvement of 33.8 points. Six hips were further revised, for a failure rate of 12.2%, four for non-union and aseptic failure of the implant (8.2%), one for infection (2%), and one for host step-cut fracture (2%). Junctional union was observed in 44 hips (89.8%). Three hips underwent re-attachment of the greater trochanter for trochanteric escape (6.1%). Asymptomatic non-union of the greater trochanter were noticed in three hips (6.1%). Moderate allograft resorption was observed in five hips (10.2%), non were full-thickness graft resorption. Two fractures of the host step-cut occurred (4.1%). There were four dislocations (8.2%), two of them developed in conjunction with trochanteric escape. By definition of success as increase of HHS by 20 points or more, and no need for any subsequent re-operation related to the allograft and/or the implant, a 75.5% rate of success was found. Kaplan-Meier survivorship analysis predicted 73% rate of survival at 12 years, with the need for further revision of the allograft and/or implant as the end point. We conclude that the good medium-term results with the use of large anatomic-specific femoral allografts justify their continued use in cases of revision hip arthroplasty with severe bone stock loss

Aim: Hip resurfacing is a bone conserving procedure with respect to proximal femoral resection. For previous generations of conservative hip replacement, preservation of the natural femoral head diameter necessitated additional sacrifice of acetabular bone in order to accommodate a sufficiently thick polyethylene acetabular component. We have investigated whether the BHR offers a bone conserving procedure with respect to the acetabular bone stock. Method: We reviewed 284 Birmingham resurfacing hip replacements (BHR), and 479, primary hip replacements, in which an uncemented acetabular component (THUA) was used. The BHR and THUA group had mean age at surgery of 55 and 65 years respectively. In 32 BHR’s and 21 THUA, pre-operative templating measurements were available for subsequent comparison with size of component implanted. Results: Comparison of component sizes, for both implant types, confirmed bi-modal distribution according to patient gender. BHR cups, implanted by the first author, in females, were significantly smaller than those implanted, by the same author, in THUA,(p< 0.0001). Pre-operative templating overestimated component size for all groups but the difference was only significant in male BHR cases;(p=0.03). BHR cups implanted by the first author were significantly smaller than the second author, for both male (p= 0.0001) and female patients;(p< 0.001). Conclusion: In females, BHR is bone a conserving procedure for femoral and acetabular components. In males, the procedure is not bone sacrificing when compared to THUA. Pre-operative templating can overestimate size of acetabular component that will be used for men. A significant difference was found between size of acetabular components used by two surgeons for BHR

Calcium sulphate is now a proven adjunct to the replenishment of bone stock in joint replacement surgery. Alone and as a composite, it has been used successfully for many years in both dental and orthopaedic applications. OsteoSet (Wright Medical Technology), a processed, purified material, has been used as a bone void filler in 51 revision total hip arthroplasty (THA) procedures. Follow-up of these cases ranges from 3 to 48 months. Radiographs show that the calcium sulphate has disappeared in all cases. In all but three patients, all of whom had failure of the acetabular component or infection, the calcium sulphate has been replaced with what appears to be trabeculated cancellous bone. Clinical results for cases that did not have mechanical failure or infection are indistinguishable from any revision THA in which the acetabular component is well fixed. Implantation of the calcium sulphate pellets calls for preparation of a well vascularised bed. The pellets are placed in such a way that load is not transferred to them from the implanted acetabular component. Rather, the load should be transferred from the acetabular component directly to host bone. Postoperatively, load bearing is limited for at least eight weeks and for longer of the quality of the supporting bone is poor

Introduction: Revision surgery in periprosthetic infection often encounters defects in bone stock caused by the loosening procedures, through continuous revisions or by explantation techniques. Since bony reconstruction in the presence of infection is critical, if no antibiotic impregnated bone grafts are available, metal implants are the last resort. Lately tantalum wedges and cones have been introduced as a stable augmentation device. Material and Methods: Since 2007 we have used 14 tantalum implants to fill bone defects in 13 cases of severe purulent periprosthetic infection (4 cones, 10 wedges). All patients are in permanent control on an outpatient basis. Results: Primary and continuous stability was achieved in all patients and no signs of recurrent or persistent infection were found. Conclusion: So far this concept proves to be successful and can be recommended. The stability of the implant is recorded for numerous aseptic reconstructions. Research is needed towards the surface properties of tantalum in contact with bacteria. Positive findings like in silver coating would be desirable. Further research towards impregnation possibilities of the porous structure with antibiotics for continuous elution like from cement or fleece could – in a positive result – improve septic surgery substantially

Hip resurfacing is widely recognised as a bone conserving procedure with respect to proximal femoral resection. However, it has been argued that this is not the case for the acetabulum due to the thickness of the acetabular component and the large diameter bearing surfaces. We have investigated whether the Birmingham Hip is a bone conserving procedure with respect to the acetabular bone stock. Data was obtained from 257 consecutive Midland Medical Technology (MMT) surface replacements and 458 primary hybrid total hip replacements implanted under our care. The surface replacement group comprised 185 males (185 hips) and 72 females (72 hips) with a mean age at surgery of 55 years. The hybrid primary total hip replacement group comprised 207 males (207) and 251 females (251 hips). The mean age at surgery was 65 years old. In the surface replacement group the mean uncemented acetabular size implanted was 54.88 mm (females = 51.9 mm; males = 57.8 mm). In the hybrid primary total hip replacement group the mean uncemented acetabular size of 55.04 mm (females =52.9 mm; males = 57.2 mm). Statistical analysis was undertaken to compare the uncemented acetabular sizes in the surface replacement group with the uncemented acetabular sizes implanted in the primary hybrid total hip replacement group. We report no significant difference in the size of acetabular component used for the two groups (p = 0.4629; 95% C.I. −0.28 to 0.61). The effect of gender was analysed and the mean size of uncemented acetabular component implanted in males for the surface replacement group was not significantly different (p = 0.06) to the hybrid primary total hip replacement group. However the mean size of uncemented acetabular component in females for the surface replacement group was significantly smaller (p = 0.016) compared to the primary total hip replacement group. We conclude hip resurfacing is not bone sacrificing on the acetabular bone stock and can be bone conserving for females

Femoral components in total hip replacements fail in well-known ways. There is vertical sink, posterior rotation and pivot, either distal or mid-stem. In order to sink, the stem moves into valgus and then slides down the inside of the calcar. It does not cut through the calcar.

To prevent sink and pivot, a canal filling stem is required. Canal fill prevents the stem from moving into valgus and, therefore, it will not sink. Two centimeters with complete canal fill is adequate in a primary stem. A long stem will give longer canal fill in a revision. Sharp distal flutes will prevent rotation. The distal end of the stem should be polished. One is looking for a distal stability, not distal fixation.

If the isthmus is intact, a primary stem can be used. If the isthmus is damaged, a long stem is necessary. If the calcar is intact, a primary neck is adequate. If the calcar is missing down to the level of the lesser trochanter, a calcar replacement neck is required. If there is more than 70 millimeters of completely missing proximal femur, a structural allograft is required.

If the proximal femur is damaged, the ability to place a sleeve or collar to seek the best bone available independently of the stem version is very helpful.

No matter how poor the proximal bone quality is, it can be supplemented by cerclage wires. The implant will sink only if the cerclage wires break.

The advantage of proximal fixation is that loading the proximal femur speeds recovery. The huge disadvantage of distal fixation is removal of the implant should it become necessary.

My long term results for the S-ROM stem used in revision are now out over 20 years. There were 119 primary stems with a minimum follow up of 5 years with no revisions for aseptic loosening.

There were 262 long stems used. Nine (3.7%) underwent aseptic loosening. Most of these were due to technical errors due to my inexperience in the learning process of revision surgery. Four were dependent on strut-grafts and should have been treated with structural allografts.

There were seven cases with structural allografts. Three were revised. Again, these were largely from problems arising from inexperience.

I believe proximal modularity with distal stability allows the vast majority of revision cases to be treated with proximal fixation.