Routine Total Hip Arthroplasty Research Articles

Equivalent revision rates and patient reported outcomes with routine use of a short (125mm) cemented stem for total hip arthroplasty compared to a standard length (150mm) cemented stem. A two surgeon series of 1335 patients.

Routine total hip arthroplasty (THA) using a short cemented stem as compared with a standard length cemented stem may have benefits in terms of stress distribution, bone preservation, stem subsidence and ease of revision surgery. Two senior arthroplasty surgeons transitioned their routine femoral implant from a standard 150mm Exeter V40 cemented stem to a short 125mm Exeter V40 cemented stem for all patients over the course of several years. We analysed revision rates, adjusted survival, and PROMS scores for patients who received a standard stem and a short stem in routine THA. All THAs performed by the two surgeons between January 2011 and December 2021 were included. All procedures were performed using either a 150mm or 125mm Exeter V40 stem. Demographic data, acetabular implant type, and outcome data including implant survival, reason for revision, and post-operative Oxford Hip Scores were obtained from the New Zealand Joint Registry (NZJR), and detailed survival analyses were performed. Primary outcome was revision for any reason. Reason for revision, including femoral or acetabular failure, and time to revision were also recorded. 1335 THAs were included. 516 using the 150mm stem and 819 using the 125mm stem. There were 4055.5 and 3227.8 component years analysed in the standard stem and short stem groups respectively due to a longer mean follow up in the 150mm group. Patient reported outcomes were comparable across all groups. Revision rates were comparable between the standard 150mm stem (0.44 revisions/100 component years) and the short 125mm stem (0.56 revisions/100 component years) with no statistically significant difference found (p = 0.240). Routine use of a short 125mm stem had no statistically significant impact on revision rate or PROMS scores when compared to a standard 150mm stem. There may be benefits to routine use of a short cemented femoral implant.

Survival of total hip arthroplasty (THA) in sickle cell disease.

The objective of this study was to evaluate the outcome of THA done in patients with sickle cell disease at a single center, and compare with rest of the world before we could recommend routine THA in SCD patients. In 92 patients, 117 THAs were performed in sickle cell patients. Seventy-six (76) patients had homozygous hemoglobin (Hgb SS) disease, whereas sixteen had sickle cell trait (Hgb AS). Patients with Grade III Ficat and above avascular necrosis of the head of femur (ANFH) with cementless porous-coated proximal femur fixation were included in this analysis. Harris hip score was modified (MHHS) and used for assessment of improvement and visual analog scale score (VAS), for pain assessment. VAS improved from average pre-operative mean of 7 (7-9) to 2.5 (1-5). The average pre-operative MHHS was 44 (32-63), and it improved to 79 (71-88) in the final mean follow-up of 12.4 (4-18) years. Nine patients (9.7%) had complications and revision surgery was required in seven (5.9%) for aseptic loosening. Our analysis shows that THA in sickle cell disease is safe with average 12years of follow-up, indicating that surgery in these young patients (≤ 25years) is safe and should not be delayed.

Quantitative determination of the femoral offset templating error in total hip arthroplasty using a new geometric model.

Traditionally, total hip arthroplasty (THA) templating has been performed on anteroposterior (AP) pelvis radiographs. Recently, additional AP hip radiographs have been recommended for accurate measurement of the femoral offset (FO). To verify this claim, this study aimed to establish quantitative data of the measurement error of the FO in relation to leg position and X-ray source position using a newly developed geometric model and clinical data. We analyzed the FOs measured on AP hip and pelvis radiographs in a prospective consecutive series of 55 patients undergoing unilateral primary THA for hip osteoarthritis. To determine sample size, a power analysis was performed. Patients' position and X-ray beam setting followed a standardized protocol to achieve reproducible projections. All images were calibrated with the KingMark calibration system. In addition, a geometric model was created to evaluate both the effects of leg position (rotation and abduction/adduction) and the effects of X-ray source position on FO measurement. The mean FOs measured on AP hip and pelvis radiographs were 38.0 mm (SD 6.4) and 36.6 mm (SD 6.3) (p < 0.001), respectively. Radiological view had a smaller effect on FO measurement than inaccurate leg positioning. The model showed a non-linear relationship between projected FO and femoral neck orientation; at 30° external neck rotation (with reference to the detector plane), a true FO of 40 mm was underestimated by up to 20% (7.8 mm). With a neutral to mild external neck rotation (≤ 15°), the underestimation was less than 7% (2.7 mm). The effect of abduction and adduction was negligible. For routine THA templating, an AP pelvis radiograph remains the gold standard. Only patients with femoral neck malrotation > 15° on the AP pelvis view, e.g. due to external rotation contracture, should receive further imaging. Options include an additional AP hip view with elevation of the entire affected hip to align the femoral neck more parallel to the detector, or a CT scan in more severe cases.Cite this article: Bone Jt Open2022;3(10):795-803.

Is rationing of total hip arthroplasty justified? Working to optimize patient accessibility to surgery using long-term patient-reported outcome data.

AimsThe aim of this study was to assess medium-term improvements following total hip arthroplasty (THA), and to evaluate what effect different preoperative Oxford Hip Score (OHS) thresholds for treatment may have on patients’ access to THA and outcomes.MethodsPatients undergoing primary THA at our institution with an OHS both preoperatively and at least four years postoperatively were included. Rationing thresholds were explored to identify possible deprivation of OHS improvement.ResultsOverall, 2,341 patients were included. Mean OHS was 19.7 (SD 8.2) preoperatively and 39.7 (SD 9.8) at latest follow-up. An improvement of at least eight-points, the minimally important change (MIC), was seen in 2,072 patients (88.5%). The mean improvement was 20.0 points (SD 10.5). If a rationing threshold of OHS of 20 points had been enforced, 90.8% of those treated would have achieved the MIC, but only 54.3% of our cohort would have had access to surgery; increasing this threshold to 32 would have enabled 89.5% of those treated to achieve the MIC while only depriving 6.5% of our cohort. The ‘rationed’ group of OHS > 20 had significantly better OHS at latest follow-up (42.6 vs 37.3; p < 0.001), while extending the rationing threshold above 32 showed postoperative scores were more significantly affected by the ceiling effect of the OHS.ConclusionThe OHS was not designed as a tool to ration healthcare, but if it had been used at our institution for this cohort, applying an OHS threshold of 20 to routine THA access would have excluded nearly half of patients from having a THA; a group in which over 85% had a significant improvement in OHS. Where its use for rationing is deemed necessary, use of a higher threshold may be more appropriate to ensure a better balance between patient access to treatment and chances of achieving good to excellent outcomes.Cite this article: Bone Jt Open 2022;3(3):196–204.

Does robotic-assisted surgery improve outcomes of total hip arthroplasty compared to manual technique? A systematic review and meta-analysis.

Robot-assisted total hip arthroplasty (THA) is an emerging technology that claims to position implants with very high accuracy. However, there is currently limited data in literature on whether this improved accuracy leads to better long-term clinical outcomes. This systematic review compares the outcomes of THA done with the help of robotic assistance (RA) to those done with conventional manual techniques (MTs). Four electronic databases were searched for eligible articles that directly compared robot-assisted THA to manual THA and had data on the radiological or clinical outcomes of both. Data on various outcome parameters were collected. Meta-analysis was conducted using a random-effects model with 95% CIs. A total of 17 articles were found eligible for inclusion, and 3600 cases were analysed. Mean operating time in the RA group was significantly longer than in the MT group. RA resulted in significantly more acetabular cups being placed inside Lewinnek's and Callanan's safe zones (p<0.001) and had significantly reduced limb length discrepancy compared with MT. There were no statistically significant differences in the two groups in terms of incidence of perioperative complications, need for revision surgery and long-term functional outcome. RA leads to highly accurate implant placement and leads to significantly reduced limb length discrepancies. However, the authors do not recommend robot-assisted techniques for routine THAs due to lack of adequate long-term follow-up data, prolonged surgical times and no significant differences in the rate of complications and implant survivorship compared with conventional MTs.

Short-term effectiveness of Mako robot-assisted total hip arthroplasty via posterolateral approach

To explore the short-term effectiveness of Mako robot-assisted total hip arthroplasty (THA) via posterolateral approach. The clinical data of 64 patients (74 hips) treated with Mako robot-assisted THA via posterolateral approach (robot group) between May 2020 and March 2021 were retrospectively analyzed and compared with the clinical data of 52 patients (55 hips) treated with traditional THA via posterolateral approach (control group) in the same period. There was no significant difference in general data such as gender, age, side, body mass index, disease type, and preoperative Harris score between the two groups ( P>0.05). The operation time, intraoperative blood loss, and complications were recorded and compared between the two groups. Acetabular inclination angle, acetabular anteversion angle, and lower limbs discrepancy were measured after operation. At last follow-up, the improvement of hip pain and function was evaluated by visual analogue scale (VAS) score, Harris score, and forgetting joint score (FJS-12). In the robot group, 3 patients (including 1 patient with acetabular fracture during operation) were converted to routine THA because the pelvic data array placed at the anterior superior iliac spine was loose, resulting in data error and unable to register the acetabulum; the other patients in the two groups completed the operation successfully. The operation time and intraoperative blood loss in the robot group were significantly higher than those in the control group ( P<0.05). All patients were followed up 1-10 months, with an average of 4.6 months. In the robot group, 1 patient with ankylosing spondylitis had acetabular prosthesis loosening at 2 days after operation, underwent surgical revision, and 10 patients had lower limb intermuscular vein thrombosis; in the control group, 1 patient had left hip dislocation and 5 patients had lower extremity intermuscular vein thrombosis; there was no complication such as sciatic nerve injury, incision exudation, and periprosthetic infection in both groups. There was no significant difference in the incidence of complications between the robot group and the control group (17.2% vs.11.5%) ( χ 2=0.732, P=0.392). At last follow-up, the acetabular anteversion angle and FJS-12 score in the robot group were was significantly greater than those in the control group, and the lower limbs discrepancy was significantly less than that in the control group ( P<0.05); there was no significant difference in acetabular inclination angle and VAS score between the two groups ( P>0.05). The Harris scores of the two groups were significantly improved when compared with those before operation ( P<0.05), but there was no significant difference in the difference of pre- and post-operative score between the two groups ( t=1.632, P=0.119). Compared with traditional surgery, Mako robot-assisted THA can optimize the accuracy and safety of acetabular cup implantation, reduce the length difference of the lower limbs, and has a certain learning curve. Its long-term effectiveness needs further research to confirm.

Human IgA-Expressing Bone Marrow Plasma Cells Characteristically Upregulate Programmed Cell Death Protein-1 Upon B Cell Receptor Stimulation

The functions of bone marrow plasma cells (BMPC) beyond antibody production are not fully elucidated and distinct subsets of BMPC suggest potential different functions. Phenotypic differences were identified for human BMPC depending on CD19 expression. Since CD19 is a co-stimulatory molecule of the B-cell-receptor (BCR), and IgA+ and IgM+ BMPC express the BCR on their surface, we here studied whether CD19 expression affects cellular responses, such as BCR signaling and the expression of checkpoint molecules. We analyzed 132 BM samples from individuals undergoing routine total hip arthroplasty. We found that both CD19+ and CD19− BMPC expressed BCR signaling molecules. Notably, the BCR-associated kinase spleen tyrosine kinase (SYK) including pSYK was higher expressed in CD19+ BMPC compared to CD19− BMPC. BCR stimulation also resulted in increased kinase phosphorylation downstream of the BCR while expression of CD19 remained stable afterwards. Interestingly, the BCR response was restricted to IgA+ BMPC independently of CD19 expression. With regard to the expression of checkpoint molecules, CD19− BMPC expressed higher levels of co-inhibitory molecule programmed cell death protein-1 (PD-1) than CD19+ BMPC. IgA+ BMPC characteristically upregulated PD-1 upon BCR stimulation in contrast to other PC subsets and inhibition of the kinase SYK abrogated PD-1 upregulation. In contrast, expression of PD-1 ligand, B and T lymphocyte attenuator (BTLA) and CD28 did not change upon BCR activation of IgA+ BMPC. Here, we identify a distinct characteristic of IgA+ BMPC that is independent of the phenotypic heterogeneity of the subsets according to their CD19 expression. The data suggest that IgA+ BMPC underlie different regulatory principles and/or exert distinct regulatory functions.

Assessment of the Learning Curve of Supercapsular Percutaneously Assisted Total Hip Arthroplasty in an Asian Population

The supercapsular percutaneously assisted total hip (SuperPATH) approach is a microinvasive approach that was developed to minimize surgical disruption of soft tissue during routine total hip arthroplasty (THA). This study was aimed at assessing early outcomes and learning curves of the SuperPATH approach in one Chinese hospital's experience. Early outcomes of the first consecutive 78 SuperPATH cases (80 hips) performed by the same surgeon were evaluated. The patients were divided into 4 groups according to the surgical order. The incision, intraoperative blood loss, hospital stay, Harris hip score, and complication occurrence in each group were evaluated. Learning curves were assessed using operative time and intraoperative blood loss as surrogates. The operation time and intraoperative blood loss of groups A and B were more than those of groups C and D, and the difference was statistically significant (P < 0.05); however, there was no statistically significant difference between the two groups (group A vs. group B, P = 0.426; group A vs. group B, P = 0.426). There was no statistically significant difference in terms of incision length and hospital stay, and Harris hip score at the last follow-up was increased with statistically significant difference when compared with that preoperatively among the 4 groups. One case of periprosthetic fracture occurred in group A. No other complication, such as joint dislocation, sciatic nerve injury, prosthesis loosening, periprosthetic infection, and deep vein thromboembolism, occurred in the 4 groups. In summary, for surgeons who are familiar with the standard posterolateral approach, they could achieve more familiarity with SuperPATH after 40 cases of surgery.

Advantages of an Anterior-Based Muscle-Sparing Approach in Transitioning From a Posterior Approach for Total Hip Arthroplasty: Minimizing the Learning Curve

BackgroundEnthusiasm for anterior-based approaches for total hip arthroplasty (THA) continues to increase but there is concern for increased complications during the learning curve period associated. This study aimed to investigate if there was a difference in perioperative variables, intraoperative and immediate postoperative complications, or patient-reported outcomes when transitioning from a mini-posterior approach (mPA) to an anterior-based muscle-sparing (ABMS) approach for THA. MethodsRetrospective cohort study on the first 100 primary THA cases (n = 96 patients) of the senior author (August 2016 to August 2017) using the ABMS approach. These cases were compared to primary THA cases done the year prior (July 2015 to July 2016, n = 91 cases in 89 patients) using an mPA. Data were extracted and analyzed via gamma regression with robust standard errors and using generalized estimating equation regression. ResultsWe found no difference in the estimated blood loss (P = .452) and surgical time (P = .564) between the cohorts. The ABMS cases had a slightly shorter length of stay (P = .001) with an adjusted mean length of stay of 1.53 days (95% confidence interval 1.4-1.6) compared to 1.85 days (95% confidence interval 1.8-1.9) in the mPA cases. There was no difference in the frequency of immediate postoperative complications (all, P > .05). There was no difference in the adjusted mean change in patient-reported outcomes (all P > .05). In the ABMS group, there was no difference in surgical time or physical function computerized adaptive test between the first 20 cases (reference) and each subsequent group of 20 cases (all P > .05). ConclusionThis study demonstrates no associated learning curve for an experienced senior surgeon when switching routine THA approach from mPA to ABMS. We advise careful interpretation of our results, as they may not apply to all surgeons and practices. Level of EvidenceLevel III Therapeutic Study: retrospective comparative study.

Scanning electron microscopical observation of an osteoblast/osteoclast co-culture on micropatterned orthopaedic ceramics

Category: Basic Sciences/Biologics Introduction/Purpose: In biomaterial engineering, the surface of an implant can influence cell differentiation, adhesion and affinity towards the implant. On contact with an implant, bone marrow-derived mesenchymal stromal cells (BMSCs) demonstrate differentiation towards bone forming osteoblasts, which can improve osteointegration. The process of micropatterning has been shown to improve osteointegration in polymers, but there are few reports surrounding ceramics. Several implants in forefoot surgery like the Moje metatarsal phalangeal joint replacement were made from smoother ceramic zirconia toughened alumina (ZTA). The aim was to establish whether the pits were specifically bioactive towards osteogenesis or were generally bioactive and would also stimulate osteoclastogenesis that could potentially lead to osteolysis. Methods: We established a co-culture of bone marrow-derived mesenchymal stromal cells (BMSCs) with osteoclast progenitor cells and to observe the response to micropatterned ZTA ceramics with 30 µm diameter pits compared to smooth controls. Micropatterned masks were fabricated using a standard photolithography and electroplating technique. Micropatterned ceramic substrates were produced by embossing of visco-plastic green ceramic tapes at room temperature followed by sintering. After informed consent was obtained from healthy patients undergoing routine total hip arthroplasty, bone marrow was aspirated from the femoral medullary canal. At day 3, non-adherent cells were removed within the supernatant and cultured separately until a confluent BMSC layer was identified. The co-culture was maintained up to specific time points (days 3, 7, 14, 21 and 28) with thrice weekly media exchange. At each time point, duplicate samples were fixed and prepared for analysis by scanning electron microscopy (SEM) with immuofluorescence and histochemical staining, Results: SEM analysis of the patterned materials demonstrated successful micropatterning of the ZTA ceramic with approximately 30 µm diameter, 1.7 µm depth pits due to sintering shrinkage. At the longest time-point (day 28), osteoclast-like cells were visible across the planar surfaces and had strong interactions with the ceramic grains. Podosomes were notable on some of the osteoclast membranes. On the pitted surfaces, we observed significantly less osteoclast-like cells. Also, pit bridging by macrophage-like cells was regularly noted. Nodular clusters of osteoblast-like cells were noted statistically more often on the micropatterned ceramics. Conclusion: These results demonstrated specific bioactivity of micropatterned ZTA ceramics towards osteogenesis, with more bone nodule formation and less osteoclastogenesis compared to planar controls. In addition, we found that that macrophage and osteoclast-like cells did not interact with the pits and formed fewer full-size osteoclast-like cells on the pitted surfaces. This may have a role when designing ceramic orthopaedic foot implants. We are now using this co-culture for research on other micropatterned biomaterials used in foot and ankle surgery.

Severe Polyethylene Wear Requiring Revision Total Hip Arthroplasty in Three Dogs.

To describe the occurrence of severe polyethylene wear of the acetabular component in 3 dogs that ultimately led to implant failure, and to report the outcome of revision of total hip arthroplasty (THA) in these cases. Case report Dogs (n=3). Three dogs with hip dysplasia underwent routine THA before 2 years of age. All dogs became acutely lame 4-5 years after THA. Radiographs revealed acetabular cup wear in all cases, shell fragmentation in 2 cases, and additional stem failure in 1 case. All dogs underwent successful revision surgery, during which severe polyethylene wear and metallosis was observed. Revision surgery provided an excellent clinical outcome in all dogs from 10 months to 4 years post revision. Polyethylene wear and implant failure may be a significant long-term complication of THA not previously recognized, which may be especially true when placed at an early age in a large breed, active dog, or in a dog with significant morbidity associated with other limbs. A successful revision was achieved in all 3 dogs. Additional investigation is warranted to document the risk factors associated with severe polyethylene wear in canine THA.

Total Hip Arthroplasty in the Ankylosed Hip

Altered biomechanics secondary to hip ankylosis often result in degeneration of the lumbar spine, ipsilateral knee, and contralateral hip and knee. Symptoms in these joints may be reduced with conversion total hip arthroplasty (THA) of the ankylosed hip. THA in the ankylosed hip is a technically challenging procedure, and the overall clinical outcome is generally less satisfactory than routine THA performed for osteoarthritis and other etiologies. Functional integrity of the hip abductor muscles is the most important predictor of walking ability following conversion THA. Many patients experience persistent limp, and it can take up to 2 years to fully assess final functional outcome. Risk factors cited for increased risk of failed THA include prior surgical ankylosis and age <50 years at the time of conversion THA.

Componente acetabular no cementado en coxartrosis por fractura de cotilo

Objective To evaluate the outcomes of cementless acetabular component for post-traumatic arthritis after acetabular fracture. Material and method A prospective study of twenty-four patients with a mean age of 56 years (range: 28-77) and a follow-up 8.4 years (range: 5-15) treated with cementless total hip arthroplasty. The time from fracture to total hip arthroplasty was 3 years (range: 5 months-14 years). The fracture had been treated conservatively in 15 cases and with internal fixation in 9 cases. A clinical assessment was made using with Harris hip score, along with radiology with special interest in the socket. Results Harris hip score increased from 35 points (range: 22-52) to 77 (range: 45-94). Unstable acetabular fixation was seen in 3 cases, 2 with osteolysis that required revision and 1 with a complete radiolucent line. The stem required revision in 1 case. There was 1 case of deep infection and 1 post-traumatic late dislocation. Survival for any cause at 12 years was 78.4%. Discussion and conclusions There are few studies on this topic, and all with a small number of cases. Acetabular failure rate is higher than routine total hip arthroplasty for non-traumatic osteoarthritis. Cementless total hip arthroplasty is a suitable treatment for post-traumatic arthritis after acetabular fracture.

Cementless acetabular component in coxarthrosis due to a acetabular fracture

Objective To evaluate the outcomes of cementless acetabular component for post-traumatic arthritis after acetabular fracture. Material and method A prospective study of twenty-four patients with a mean age of 56 years (range: 28–77) and a follow-up 8.4 years (range: 5–15) treated with cementless total hip arthroplasty. The time from fracture to total hip arthroplasty was 3 years (range: 5 months-14 years). The fracture had been treated conservatively in 15 cases and with internal fixation in 9 cases. A clinical assessment was made using with Harris hip score, along with radiology with special interest in the socket. Results Harris hip score increased from 35 points (range: 22–52) to 77 (range: 45–94). Unstable acetabular fixation was seen in 3 cases, 2 with osteolysis that required revision and 1 with a complete radiolucent line. The stem required revision in 1 case. There was 1 case of deep infection and 1 post-traumatic late dislocation. Survival for any cause at 12 years was 78.4%. Discussion and conclusions There are few studies on this topic, and all with a small number of cases. Acetabular failure rate is higher than routine total hip arthroplasty for non-traumatic osteoarthritis. Cementless total hip arthroplasty is a suitable treatment for post-traumatic arthritis after acetabular fracture.

Cemented Total Hip Arthroplasty With Subtrochanteric Osteotomy in Dysplastic Hips

Total hip arthroplasty (THA) in the presence of developmental dysplasia of the hip (DDH) can be technically challenging. Restoring the anatomic center of hip rotation may require femoral osteotomy. Techniques using cementless components are widely reported but less is known about using cemented components that may be more appropriate with osteopenic bone. We therefore determined the rate of union, complications, and early functional score in a series of patients with DDH who underwent cemented THA and simultaneous subtrochanteric osteotomy. We retrospectively reviewed 28 patients (35 hips) who underwent a cemented THA for DDH at a mean age of 47.3 years. Two patients (two hips) died within 12 months of surgery of unrelated conditions. The clinical notes and radiographs were reviewed with a minimum followup of 2 years (mean, 5.6 years; range, 2-14 years). Complications were noted. SF-12 and Oxford hip scores (OHS) were recorded for 18 patients preoperatively and after 6 and 12 months. Union occurred in 32 of 33 femora (97%); one patient had an infected nonunion. The overall revision rate was 20% (9% femoral revision rate). There were three dislocations, two of which had further surgery. Two patients had a transient neuropraxia. The mean SF-12 physical component score increased from 32 to 52 and mean SF-12 mental component score increased from 48 to 51. The mean OHS decreased from 40 to 27. Combined subtrochanteric osteotomy and cemented THA is technically demanding with a higher complication rate than routine THA. The rate of union, complications, implant survival, and early OHS were comparable to those for similar techniques using cementless components.

Total Hip Arthroplasty Following Previous Acetabular Fracture

For patients with end-stage post-traumatic arthritis or osteonecrosis of the femoral head, conversion total hip arthroplasty (THA) can be an effective treatment option. It is more technically difficult than routine THA for inflammatory arthritis or osteoarthritis and it is associated with more complications. Preparation of the acetabulum is often the most technically challenging aspect of the operation. Newer technology is available to improve implant fixation. Surgical techniques will vary by acetabular defect type and size, and the use of bone graft is frequently required. Removal of previous hardware is not always required. Heterotopic ossification should be addressed with excision and appropriate prophylaxis instituted. A review of recent literature suggests that cementless fixation and improved implant design have improved the clinical outcome in these patients.

Penetration of Moxifloxacin and Levofloxacin into Cancellous and Cortical Bone in Patients Undergoing Total Hip Arthroplasty

Penetration of levofloxacin and moxifloxacin into cancellous and cortical bone was studied using high-performance liquid chromatography (HPLC) in 16 patients who underwent routine total hip arthroplasty. Our results demonstrate a good degree of penetration into bone for both quinolones. The mean cancellous penetration was 53.86% for moxifloxacin and 54.13% for levofloxacin. The penetration into cortical bone was 41.59% and 34.26% respectively. The concentrations for both quinolones were above the minimum inhibitory concentration (MIC90s) for the most common pathogens, so they can be used for the treatment of osteomyelitis.

Penetration of linezolid into bone, fat, muscle and haematoma of patients undergoing routine hip replacement.

Twelve patients undergoing total hip replacement were given 600 mg of linezolid as a 20 min iv infusion along with conventional prophylaxis of 1 g of cefamandole immediately before surgery. Routine total hip arthroplasty was carried out, and at timed intervals during surgery samples of bone, fat, muscle and blood were collected for assay by high-performance liquid chromatography analysis. Samples of the haematoma fluid that formed around the operation site and further blood samples for assay were also collected at timed intervals following the operation. The penetration of linezolid into bone was rapid, with mean concentrations of 9.1 mg/L (95% CI 7.7-10.6 mg/L) achieved at 10 min after the infusion, decreasing to 6.3 mg/L (95% CI 3.9-8.6 mg/L) at 30 min. Correction for the simultaneous blood concentrations gave mean values for bone penetration of 51% at 10 min, 60% at 20 min and 47% at 30 min. Although the penetration of linezolid into fat was also rapid, mean concentrations and degree of penetration were c. 60% of those in bone; at 10 min they were 4.5 mg/L (95% CI 3.0-6.1 mg/L; penetration 27%); at 20 min they were 5.2 mg/L (95% CI 4.0-6.4 mg/L; penetration 37%); and at 30 min, 4.1 mg/L (95% CI 3.3-4.8 mg/L; penetration 31%). For muscle the corresponding values were 10.4 mg/L (95% CI 8.1-12.7 mg/L; penetration 58%) at 10 min, 13.4 mg/L (95% CI 10.2-16.5 mg/L; penetration 94%) at 20 min and 12.0 mg/L (95% CI 9.2-14.8 mg/L; penetration 93%) at 30 min. Mean concentrations of linezolid in the haematoma fluid drained from around the operation site were 8.2 mg/L at 6-8 h and 5.6 mg/L at 10-12 h after the infusion, and 7.0 mg/L at 2-4 h following a second 600 mg infusion given 12 h post-operatively. We conclude that linezolid exhibits rapid penetration into bone, fat and muscle of patients undergoing hip arthroplasty, to achieve levels in excess of its MIC for susceptible organisms (< or=4 mg/L); therapeutic concentrations were maintained in the haematoma fluid that surrounds the operation site for >16 h.

Total hip arthroplasty after operative treatment of an acetabular fracture.

Sixty-six primary total hip arthroplasties were performed to treat post-traumatic osteoarthrosis that had developed following an acetabular fracture and subsequent open reduction and internal fixation. The mean age of the patients at the time of the total hip arthroplasty was fifty-two years (range, nineteen to eighty years). The arthroplasty was performed with cement in forty-four hips and without cement in twenty hips; in the remaining two hips, the acetabular component was inserted without cement and the femoral component was inserted with cement (a so-called hybrid procedure). Scarring from a previous procedure, retained hardware, heterotopic bone, and residual osseous deformity and deficiency made the procedure more complex than routine total hip arthroplasty in most patients. However, only one of the sixty-six procedures was associated with an operative complication. Three patients were lost to follow-up. The remaining sixty-three patients were followed for a mean of 9.6 years (range, two to twenty years). The mean duration of follow-up was 14.9 years for the acetabular components inserted with cement, 11.6 years for the femoral components inserted with cement, 4.6 years for the femoral components inserted without cement, and 3.9 years for the acetabular components inserted without cement. The mean Harris hip score improved from 49 points preoperatively to 93 points at the latest follow-up evaluation for the forty-six patients who did not have a revision procedure after the index arthroplasty. Seventeen patients had a revision; sixteen revisions were performed because of aseptic loosening of one or both components (nine acetabular and eleven femoral components). Mechanical failure (radiographic loosening or revision due to aseptic loosening) occurred in twenty-five hips. As determined with use of the Kaplan-Meier method, the ten-year survival rate, with revision due to aseptic loosening as the end point, was 78 per cent (95 per cent confidence interval, 66 to 92 per cent) for the prosthesis as a whole (that is, no revision of either component), 87 per cent (95 per cent confidence interval, 76 to 99 per cent) for the acetabular component, and 84 per cent (95 per cent confidence interval, 72 to 97 per cent) for the femoral component. An age of less than fifty years (p = 0.02), a weight of eighty kilograms or more (p = 0.047), and large residual combined segmental and cavitary deficiencies in the acetabular bone (p < 0.0001) were significant risk factors for revision because of aseptic loosening. At the ten-year follow-up, none of the twenty-two acetabular components that had been inserted without cement had been revised or demonstrated radiographic loosening. The ten-year rate of failure due to aseptic loosening was higher than that in many reported series of total hip arthroplasties performed for other indications; this was probably partly because of the young mean age of the patients, the high number of patients who had Charnley class-A involvement, and the predominantly male cohort.

Preliminary Results of an Off-the-shelf Press-Fit Stem

The use of custom-manufactured femoral prostheses as part of routine total hip arthroplasty (THA) has been suggested. However, there are several disadvantages, including possible inaccuracy of fit, inadequate instrumentation, and high cost. A series of 28 THAs (including 18% for revision of failed, cemented THA) using a press-fit prosthesis of contemporary design were investigated. The average follow-up period was 28 months (range, 12-49 months). Clinical results were overall very good, even in revision cases. Roentgenographic changes included rapid femoral remodeling, which may increase component stability. Given the clinical and roentgenographic results obtained in this complex-problem patient population, it is difficult to justify the use of custom femoral components in routine THA.