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BACKGROUND: Recently, surgeons introduced a minimally invasive modification on the classic posterolateral approach (PLA) in total hip arthroplasty (THA): the direct superior approach (DSA). We investigated the association between surgeon's experience and the risk of early revision of the DSA in primary THA, using data from the Dutch Arthroplasty Register (LROI). METHODS: We retrieved all primary THAs performed using the DSA in 4 hospitals between 2016 and 2022 (n = 1551). Procedures were sorted in 5 groups using the date of operation and number of previous procedures per surgeon: 1-25; 26-50; 51-75; 76-100; >100. Subsequently, data from different surgeons were pooled together and the risk of revision was calculated via a multilevel time-to-event analysis. RESULTS: The overall revision rate was 1.5% after a mean follow-up of 2 years. Patients from the 1-25 group had comparable risks of revision compared to patients in the >100 group (hazard ratio [HR] 1.0 [CI, 0.3-3.2]). The risk for patients in groups 26-50, 51-75 and 75-100 was also not statistically different from the >100 group (resp. HR 1.5 [CI, 0.5-5.0], 1.8 [CI, 0.5-6.4] and 0.5 [CI, 0.1-4.0]). Main reasons of revision were dislocation (0.5%) and infection (0.4%). CONCLUSIONS: We did not identify an association between the surgeon's experience and the early risk of revision for the DSA in primary THA in the Netherlands. The DSA seems safe in the early adoption phases with a low risk of revision due to dislocation and revision for all other causes.

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BACKGROUND: To reduce the risk of dislocation, larger head size can be used in total hip arthroplasty (THA). However, larger head size leads to thinner acetabular liners. With conventional polyethylene, thickness of >8 mm has been advocated to reduce stress and wear rate of the polyethylene. Modern polyethylene has become more wear-resistant. In this study, we investigated if the thickness of sequentially cross-linked polyethylene (XLPE) liners is associated with failure of THA in the medium term. PATIENTS AND METHODS: 3654 THAs were included (2009-2016), in which THA was performed with a XLPE liner in combination with a 36-mm femoral head. Patient and surgical characteristics were collected. We compared implant survival of THA with thin liners (<7.9 mm) and thick liners (⩾7.9 mm) with a Kaplan Meier survival analysis at 5 years, median follow-up and 10 years of follow-up with and point aseptic loosening and performed a multivariate analysis to estimate hazard ratios (HR). RESULTS: Median follow-up was 7.7 years (IQR 5.6-9.8). In total, 179 revision procedures were performed, where 82 revisions (46%) were performed for aseptic loosening. The survival rate at 5 years, median and 10 years of follow-up showed no statistically significant difference in implant survival. The survival rate at 10 years follow-up was for thin liners 97.1% (95% CI, 96.3-97.9) and for thick liners 98.2% (95% CI, 97.4-99.0) in the aseptic loosening group (chi-square 2.55; p = 0.11).The adjusted HR for thick liners (⩾7.9 mm) was 0.65 (95% CI, 0.38-1.08) compared with the thin liners (<7.9 mm), which was not significantly different. CONCLUSIONS: From this single-centre retrospective study it appears that thinner polyethylene liners are well tolerated when using second-generation highly cross-linked polyethylene. Thickness of the XLPE liners did not influence the risk of aseptic loosening of the implants in the medium term.

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BACKGROUND AND PURPOSE: The direct superior approach (DSA) is a modification of the posterolateral approach (PLA) for total hip arthroplasty (THA). Patient-reported outcome measures (PROMs) of the DSA have not been investigated previously using nationwide data. Our aim was to assess PROMs after THA using the DSA compared with the PLA and, secondarily, with the anterior approach (DAA). PATIENTS AND METHODS: In this population-based cohort study we included 37,976 primary THAs performed between 2014 and 2020 (PLA: n = 22,616; DAA: n = 15,017; DSA: n = 343) using Dutch Arthroplasty Registry data. PROMs (NRS pain, EQ-5D, HOOS-PS, and OHS) were measured preoperatively, and at 3 and 12 months postoperatively. Repeated measurements were analyzed using mixed-effects models, adjusted for confounders, to investigate the association between surgical approach and PROMs over time. RESULTS: From baseline to 3 and 12 months, improvements for NRS pain scores, EQ-5D, and OHS were comparable for the DSA compared with the PLA or DAA. No difference was found in HOOS-PS improvement 3 months postoperatively between DSA and PLA (-0.2, 95% confidence interval [CI] -2.4 to 1.9) and between DSA and DAA (-1.7, CI -3.9 to 0.5). At 12 months postoperatively, patients in the DSA group had improved -2.8 points (CI -4.9 to -0.6) more in HOOS-PS compared with the DAA, but not with the PLA group (-1.0, CI -3.2 to 1.1). CONCLUSION: Our study showed no clinically meaningful differences between the DSA and either PLA or DAA.

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BACKGROUND AND PURPOSE: The direct superior approach (DSA) is a modification of the classic posterolateral approach (PLA) for total hip arthroplasty (THA), in which the iliotibial band and short external rotators are spared. The revision rate of the DSA has not been investigated previously using arthroplasty registry data. We examined the reasons and risk of revision of the DSA, compared with the direct anterior approach (DAA) and PLA. PATIENTS AND METHODS: In this population-based cohort study we included 175,543 primary THAs performed between 2014 and 2020 (PLA, n = 117,576; DAA, n = 56,626; DSA, n = 1,341). Competing risk survival analysis and multivariable Cox proportional hazard analyses, adjusted for potential confounders, were performed. RESULTS: After 3 years, crude revision rates due to any reason were 2.1% (95% confidence interval [CI] 1.3-3.3) for DSA, and 2.9% (CI 2.8-3.0) for PLA. Crude dislocation revision rates were 0.3% (CI 0.1-0.8) for DSA, versus 1.0% (CI 0.9-1.0) for PLA. Dislocation revision rate for DSA did not differ from DAA (0.3% [CI 0.2-0.3]). Multivariable Cox regression analysis demonstrated no overall difference in revision rates for the DSA (HR 0.6 [CI 0.4-1.09) compared with the PLA. Lower risk of revision due to dislocation was found in patients operated on through the DSA (HR 0.3 [0.1-0.9]) compared with the PLA. CONCLUSION: Early nationwide results suggest that the DSA for total hip arthroplasty seems to show a tendency towards a lower risk of revision for dislocation but no overall reduced revision risk compared with the PLA.

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National arthroplasty registries reveal a higher risk of revision for periprosthetic fracture and dislocation after total hip arthroplasty (THA) in patients with a femoral neck fracture compared to those with osteoarthritis (OA). Since these registries may con- tain confounding factors, we conducted a single center cohort study comparing survival and reason for failure between THA for an acute femoral neck fracture and OA using the same hip prosthesis after a minimum follow-up of 2 years. We retrospectively analyzed 2782 patients who had undergone THA with an Accolade TMZF stem and a Trident cup between March 2009 and September 2014. Primary diagnosis before THA was osteoarthritis (OA group : n=2610) or acute femoral fracture (Fracture group : n=172). Patients in both groups were operated on by the same hip surgeons. Effect of diagnosis on THA survival was analyzed using Cox-regression analysis. Chi-square tests were used to illustrate the different reasons for revision between the groups. Mean follow-up was 4.6 years (2-7.6). A total of 100 revisions were performed. The revision risk was comparable between the OA and Fracture group (HR=1.04, 95% CI :0.46-2.39). No differences were found between the OA and Fracture group with respect to the occurrence of periprosthetic fractures (0.8% vs. 0.6%, p=0.71) and revisions for dislocation (0.6% vs. 1.2%, p=0.38). We found no difference in outcome or reason for revision between THA for OA or femoral neck frac- ture. Using an implant with a proven ODEP rating and having experienced hip surgeons carry out the procedures may be more important than the primary diagnosis.

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OBJECTIVES: To assess the learning curve of the direct superior approach (DSA) for total hip arthroplasty (THA) and to compare surgical, clinical, and radiological results with a matched control group using the mini posterior approach (MPA). METHODS: A prospective cohort study was performed from October 2016 to May 2017 including our first 52 patients undergoing THA using the DSA. Patients with primary osteoarthritis or osteonecrosis and a body mass index (BMI) < 35 who were eligible for surgery were included. As a control group, 52 patients who underwent the MPA were included, matched based on age, BMI, and ASA classification. In the DSA group, damage to the iliotibial tract and the distal external rotators, including the external obturator and quadriceps femoris muscles, was avoided. Outcome measures were collected, including surgical time, blood loss, postoperative pain, length of stay, implant position, use of walking aids, patient reported outcome measures (PROM), and complications. Unpaired t-tests were used to analyze differences between the DSA and the MPA group in surgical time, blood loss, length of stay, and acetabular and femoral component position. χ2 -tests were used to analyze mobility and the number of complications. Two-way repeated measures ANOVA was used to analyze pain scores and PROM between the DSA and the MPA groups. RESULTS: The mean surgical time of 61 min (SD 8) in the DSA group was longer (P < 0.001) compared to that in the MPA group, 46 min (SD 12). No differences were found in blood loss, postoperative pain, or mean length of stay in the hospital. After 6 weeks, 94% of the patients in the DSA group were able to walk inside their home without walking aids compared to 90% in the MPA group. The mobility scores were not different after follow up of 6 weeks and 1 year (P = 0.12 and P = 0.36 respectively). All PROM improved postoperatively in both the DSA and the MPA group (P < 0.01). Acetabular cup and femoral stem position were not compromised by the DSA. Complications included two Vancouver B2 periprosthetic fractures in the DSA group, of which there was one surgical-related fracture and one fracture after a traffic accident. Complications in the MPA group included one periprosthetic fracture, two hip dislocations, and one ischial neuropathy. No infections or thromboembolic events were observed. The 1-year complication rate was not different between the MPA and DSA groups (P = 0.40). CONCLUSION: The DSA can be safely introduced as no learning curve in the prosthesis position or the complication rate was found.

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Background and purpose - Partial knee replacement (PKR) survival rates vary a great deal among registries and cohort studies. These discrepancies can largely be attributed to inappropriate indications of the PKR and low thresholds for revision, but also to the PKR volume. This study used Dutch Arthroplasty Register data to analyze whether absolute PKR or proportional PKR hospital volume is associated with the risk of revision.Patients and methods - 18,134 PKRs were identified in the Dutch Arthroplasty Register from 2007 to 2016. For each year, hospitals were divided into 4 groups based on the quartiles for the absolute volume (< 22, 22-36, 36-58 and > 58 PKRs per year) and the proportional volume (< 8.5, 8.6-14.2, 14.3-25.8 and > 25.8% PKRs). Kaplan-Meier survival analysis was performed to determine survival rates. A multivariable Cox regression adjusted for age category, sex, ASA score, year of surgery, diagnosis, unicondylar side, and type of hospital was used to estimate hazard ratios (HR) for revision.Results and interpretation - Proportional PKR volume did not, but absolute PKR volume did influence the risk of revision. The adjusted HR for hospitals with an absolute volume of 22-36 PKRs per year was 1.04 (95% CI 0.91-1.20), 0.96 (CI 0.83-1.10) for the hospitals with 36-58 PKRs, and 0.74 (CI 0.62-0.89) for hospitals with more than 58 PKRs compared with hospitals that had fewer than 22 PKRs per year. So, patients treated with a PKR in a high absolute volume hospital have a lower risk of revision compared with those treated in a low absolute volume hospital.

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Background and purpose - Femoral neck fractures are commonly treated with cemented or uncemented hemiarthroplasties (HA). We evaluated differences in mortality and revision rates in this fragile patient group.Patients and methods - From January 1, 2007 until December 31, 2016, 22,356 HA procedures from the Dutch Arthroplasty Register (LROI) were included. For each HA, follow-up until death, revision, or end of follow-up (December 31, 2016) was determined. The crude revision rate was determined by competing risk analysis. Multivariable Cox regression analyses were performed to evaluate the effect of fixation method (cemented vs. uncemented) on death or revision. Age, sex, BMI, Orthopaedic Data Evaluation Panel (ODEP) rating, ASA grade, surgical approach, and previous surgery were included as potential confounders.Results - 1-year mortality rates did not differ between cemented and uncemented HA. 9-year mortality rates were 53% (95% CI 52-54) in cemented HA compared to 56% (CI 54-58) in uncemented HA. Multivariable Cox regression analysis showed similar mortality between cemented and uncemented HA (HR 1.0, CI 0.96-1.1). A statistically significantly lower 9-year revision rate of 3.1% (CI 2.7-3.6) in cemented HA compared with 5.1% (CI 4.2-6.2) in the uncemented HA was found with a lower hazard ratio for revision in cemented compared with uncemented HA (HR 0.56, CI 0.47-0.67).Interpretation - Long-term mortality rates did not differ between patients with a cemented or uncemented HA after an acute femoral neck fracture. Revision rates were lower in cemented compared with uncemented HA.

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Introduction: The Girdlestone resection arthroplasty (GRA) is a salvage procedure for a recurrent or persistent prosthetic joint infection of the hip. This procedure negatively impacts the functional outcome and presumably also diminishes health status (HS) and quality of life (QOL). However, studies investigating the QOL after GRA are lacking. This cross-sectional study compares patients with a Girdlestone situation after an infected total hip prosthesis with a normative population with regard to HS and QOL. Methods: Patients with a permanent GRA were suitable to be enrolled in the study. Subjects completed the World Health Organization Quality of life (WHOQOL-BREF) and the EuroQol 5 dimension 3 level version (EQ-5D-3L). Scores were compared with data from the normal population, from patients with a lower limb amputations and data from patients with a myocardial infarction. Results: Sixty-three patients who underwent GRA between January 2000 and March 2017 completed the questionnaire. The median time between the GRA and competing the questionnaire was 48 months (4 -436). All WHOQOL-BREF domain scores were significantly lower in GRA patients compared to the normative data (p<0.001), patients with myocardial infarction or lower limb amputation. EQ-5D-3L results showed that HS was significantly impaired in GRA patients when compared to normative data (p<0.001) and also impaired when compared to data from lower limb amputations and myocardial infarctions. Conclusion: HS and QOL scores in patients with a permanent Girdlestone situation after an infected hip prosthesis are significantly lower than Dutch normative scores. Patients with a permanent Girdlestone situation scored even lower on HS than patients with a lower limb amputation or a myocardial infarction.

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INTRODUCTION: Surgeon volume of hip arthroplasties is of importance with regard to complication and revision rates in total hip arthroplasty. For hip hemiarthroplasty, the effect of surgeon volume on outcome is far less studied. We analyzed the outcome of hip hemiarthroplasties performed by orthopedic surgeons in a retrospective cohort in different volume categories, focusing on early survival of the prosthesis and complications. METHODS: Between March 2009 and January 2014, 752 hemiarthroplasties were performed for intracapsular femoral neck fracture by 27 orthopedic surgeons in a large Dutch teaching hospital. Surgeons were divided into four groups, a resident group and three groups based on the number of total hip arthroplasties and hemiarthroplasties performed per year: a low-volume (< 10 arthroplasties per year), moderate-volume (10-35 arthroplasties per year), and high-volume groups (> 35 arthroplasties per year). Outcome measures were stem survival using a competing risk analysis, complication rates, and mortality. Chi-square tests were used to compare complication rates and mortality between groups. RESULTS: Patients were followed for a minimum of 2 years or until revision or death. Overall 60% of the patients included had died at time of follow-up. We found comparable stem survival rates in the low-volume group (n = 48), moderate-volume group (n = 201), high-volume group (n = 446), and resident group (n = 57). There were no significant differences between the groups with regard to dislocation rate, incidence of periprosthetic fracture, infection, and mortality. CONCLUSION: Surgeon volume and experience did not influence early outcome and complication rates in hip hemiarthroplasty. Hemiarthroplasty can safely be performed by both experienced hip surgeons and low-volume surgeons.

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BACKGROUND: Total hip arthroplasty (THA) is a successful procedure to treat end-stage hip osteoarthritis. The procedure is increasingly performed in adults of working age, who often wish to return to sports (RTS) and return to work (RTW). However, a systematic overview of the evidence on RTS and RTW after THA is lacking. OBJECTIVES: Our aim was to systematically review (1) the extent to which patients RTS and RTW after THA, including (2) the time to RTS and RTW. METHODS: We searched MEDLINE and Embase from inception until October 2017. Two authors screened and extracted the data, including study information, patient demographics, rehabilitation protocols and pre- and postoperative sports and work participation. Methodological quality was assessed using the Newcastle-Ottawa scale. Data on pre- and postoperative sports and work participation were pooled using descriptive statistics. RESULTS: A total of 37 studies were included, of which seven were prospective studies and 30 were retrospective studies. Methodological quality was high in 11 studies, moderate in 16 studies, and low in ten studies. RTS was reported in 14 studies. Mean RTS was 104% to the pre-surgery level and 82% to the pre-symptomatic sports level. Time to RTS varied from 16 to 28 weeks. RTW was reported in 23 studies; the mean was 69%. Time to RTW varied from 1 to 17 weeks. CONCLUSION: A great majority of patients RTS and RTW after THA within a timeframe of 28 and 17 weeks, respectively. For the increasingly younger THA population, this is valuable information that can be used in the preoperative shared decision-making process.

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INTRODUCTION: Revision hip arthroplasty is associated with higher dislocation rates than primary hip arthroplasty. A dual-mobility cup (DMC) can reduce this risk. Another problem is destruction of the acetabulum, induced by aseptic loosening of the prosthesis. Bone impaction grafting (BIG) can be used to reconstruct these defects, but is usually performed with cemented all polyethylene cups. The purpose of this study is to evaluate midterm cup survival and dislocation rate for the combination of BIG and DMC. METHODS: Between 2007 and 2013, 96 patients received 102 DMCs combined with BIG of the acetabulum during revision surgery. These data were first compared with a control group, consisting of 59 cases from the same hospital receiving a cemented all polyethylene cup combined with BIG. In addition, the control group was expanded with 41 cases operated on in 2007 in 'an orthopaedic centre of excellence', resulting in a 'combined control group' of 100 patients. Log-rank tests and chi-square tests were used to compare survival and dislocation rates, respectively. RESULTS: Cumulative survival of the DMC was 95.8% (range 3 months-7 years). This was comparable to the survival in the control groups (96.5% and 94.7%). The dislocation rate of 2.9% (3/102) in the dual-mobility group was lower (p = 0.02) compared to the dislocation rate of 11.8% (7/59) in the control group, but not (p = 0.12) compared to 8% in the combined control group (8/100). CONCLUSIONS: This study shows that combining a DMC with BIG does not compromise outcome in terms of midterm survival of the cup.

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After the low friction arthroplasty by John Charnley was no longer confined to specialized hospitals but commonplace in the general orthopedic practice, the issue remained how to most optimally reach the hip. The names of the authors of these approaches remain in a lot of cases connected to the approach. By evaluating the original articles in which the approaches are described we ascertain the original description and technique. By various sources we obtained the (short) biography of the people whose name is connected to the approach. Our research covers the biographies of colleagues Smith-Petersen, Watson-Jones, Hardinge, Charnley, Moore and Ludloff. The eponymous approaches are shown and described after the short biography on each individual. This study shows that without the work of our colleagues we cannot proceed in our profession. An understanding and knowledge of the people who dedicated themselves to developing the orthopedic surgery to the high standard it has today is the least honour we should give them.

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PURPOSE: Dislocation is a concerning complication of the posterolateral approach for total hip arthroplasty (THA). Use of a larger size femoral head and a correct repair of the posterior structures can reduce the risk on dislocation of the hip prosthesis. In this study we investigated if there was a difference in dislocation rate between transmuscular and transosseous repair of the posterior soft tissues with use of 36 mm heads. METHODS: A power analysis showed that with a standardised effect size of 0.3 and p-value of 0.05, each group should include at least 174 patients. A total of 465 consecutive primary THAs with a posterolateral approach were performed in patients with primary osteoarthritis by 3 orthopaedic surgeons. There were 246 patients operated using transmuscular repair, the other 219 by using transosseous repair. All patients were given the same prostheses. RESULTS: Dislocation rate was 1.7% in all patients with at least 1 year follow-up. No significant difference was found in dislocation between both reconstruction techniques. Clinical outcome scores were comparable between the groups. CONCLUSIONS: Transosseous and transmuscular repair were equally effective techniques in closing the posterior soft tissues after THA through the posterolateral approach, without difference in dislocation rate or complication rate.

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BACKGROUND AND PURPOSE: There is growing interest in minimally invasive surgery techniques in total hip arthroplasty (THA). In this study, we investigated the learning curve and the early complications of the direct anterior approach in hip replacement. METHODS: In the period January through December 2010, THA was performed in 46 patients for primary osteoarthritis, using the direct anterior approach. These cases were compared to a matched cohort of 46 patients who were operated on with a conventional posterolateral approach. All patients were followed for at least 1 year. RESULTS: Operating time was almost twice as long and mean blood loss was almost twice as much in the group with anterior approach. No learning effect was observed in this group regarding operating time or blood loss. Radiographic evaluation showed adequate placement of the implants in both groups. The early complication rate was higher in the anterior approach group. Mean time of hospital stay and functional outcome (with Harris hip score and Oxford hip score) were similar in both groups at the 1-year follow-up. INTERPRETATION: The direct anterior approach is a difficult technique, but adequate hip placement was achieved radiographically. Early results showed no improvement in functional outcome compared to the posterolateral approach, but there was a higher early complication rate. We did not observe any learning effect after 46 patients.

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BACKGROUND: A discussion is ongoing whether displaced femoral neck fractures in elderly patients should be treated with a non-cemented or a cemented hemiarthroplasty. A recent Cochrane analysis stresses the importance of further research into the relative merits of these techniques. We hypothesise that non-cemented hemiarthroplasty will result in at least the same technical-functional outcome and complication rate, with a shorter operation time. METHODS AND DESIGN: A randomised controlled multicentre trial will be performed.The study population consists of 200 patients of 70 years and older. Patients with a displaced femoral neck fracture will be allocated randomly to have a cemented or a non-cemented hemiarthroplasty. Data will be collected preoperatively, immediately postoperatively, and 6 weeks, 3 months and 1 year postoperatively.The main outcome measures of this study are technical-functional results of the hemiarthroplasty, duration of surgery, complications, and mid-thigh pain. Secondary outcome measures are living conditions at final follow up, self-reported health-related quality of life, and radiological evaluation of the hemiarthroplasty. CONCLUSION: A recent Cochrane analysis did not find arguments in favour of either non-cemented or cemented hemiarthroplasty. The forthcoming trial will compare treatment for a displaced femoral neck fracture by cemented versus non-cemented hemiarthroplasty. Our results will be published as soon as they become available. TRIAL REGISTRATION: Trial Registration Number NTR1508.

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UNLABELLED: Acetabular bone loss hampers implantation of a total hip arthroplasty in patients with developmental dysplasia of the hip. The bone impaction grafting technique in combination with a cemented total hip can restore the bone stock in these patients, but do these reconstructions yield satisfying long-term results? We used this technique in 28 hips (22 consecutive patients). The degree of dislocation was graded preoperatively as Crowe I in five hips, Crowe II in eight hips, Crowe III in nine hips, and Crowe IV in four hips. We present the long-term results of this bone impaction grafting technique a minimum of 10 years after surgery. Two patients died before the minimum followup of 10 years, leaving 20 patients (26 hips). Two cups were revised, one cup for a sciatic nerve palsy (at 2 years) and the other for aseptic loosening after 12 years. The cumulative survival of the cup with revision for any reason as the end point was 96% at 10 years and 84% at 15 years. There were no femoral revisions during followup. The bone impaction grafting technique in combination with a cemented cup is an effective technique for developmental dysplasia of the hip with favorable long-term results. LEVEL OF EVIDENCE: Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

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Bone impaction grafting of the femur is associated with more complications when segmental defects are present. The effect of segmental defect repair on initial stem stability was studied in an in vitro study with fresh-frozen goat femora. A standardized medial segmental defect was reconstructed using a cortical strut or a metal mesh. As controls, we used intact femora and femora with a nonreconstructed defect. In all 4 groups, impacted bone grafting was performed in combination with a cemented Exeter stem. Each group contained 5 femora. Reconstructions were dynamically loaded up to 1,500 N. Migration was measured with Roentgen stereophotogrammetric analysis. All cases with a nonreconstructed segmental defect failed into excessive varus rotation. None of the femora with a reconstructed defect failed. Cortical struts and metal meshes were equally effective in creating a stable stem construction (varus rotation, 2.89 +/- 2.27 and 2.27 +/- 0.57, respectively). Reconstructions with a metal mesh were more reproducible, although the obtained stability was significantly lower (P<.01) when compared with impaction grafting in an intact femur (varus rotation, 0.58 +/- 0.36).

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Segmental defects can be reconstructed with a cortical strut or a metal wire mesh when using bone impaction grafting in the femur. We hypothesized that structural grafts would negatively influence revascularization of the underlying impacted grafts compared with an open wire mesh. A standardized large medial wall defect was reconstructed with a strut or a mesh in six goats per group. In all femurs impaction grafting was done in combination with a cemented collarless double-tapered highly polished Exeter stem. After 6 weeks the femurs were harvested. A high rate of periprosthetic fractures was observed (three of seven and two of six for the strut and mesh groups, respectively). Histologic analysis showed different revascularization and tissue ingrowth patterns for both reconstruction techniques. In the strut group, fibrous tissue ingrowth was limited to the edges of the defect. Medially behind the strut no or limited fibrous tissue ingrowth was found. In the mesh group, fibrous tissue and blood vessels penetrated the mesh and a superficial zone of revascularized grafts was observed. Although revascularization, concomitant graft resorption and bone incorporation may compromise the short-term stability of the stem after surgery, the long-term stability of the stem probably is best guaranteed by graft incorporation.

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We determined the effect of bone graft particle size and impaction technique on the initial stability of cemented acetabular cups. First, acetabular reconstructions were performed in human cadaveric pelvic bones in which type 2 AAOS cavitary defects were created. Reconstructions were made with small bone grafts (average 2 mm) produced by a bone mill or large bone grafts (average 9 mm) produced by hand with a rongeur. All chips were made from freshly-frozen femoral heads. Impaction was done using acetabular impactors and a hammer. We did a loading experiment with a gradually increasing dynamic load up to 3000 N. We used radiostereometric analysis (RSA) to determine cup stability. The cups were more stable when large bone grafts were used. Because of limitations of the cadaver model, we developed a synthetic acetabular model. For validation of this model, we repeated the experiments using small and large bone grafts. The results with both models were similar. In the synthetic model, we compared impaction with hammer and impactors with the reversed reaming technique using manual compression on the reamer. The latter method resulted in more migration. We recommend firm impaction with a hammer of large bone grafts for optimal stability of the cup.

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