Meta-analysis of randomised controlled trials comparing unipolar with bipolar hemiarthroplasty for displaced femoral-neck fractures

Purpose

Unipolar and bipolar hemiarthroplasty (HA) are used to treat displaced femoral-neck fractures. However, which type is best for treating displaced femoral-neck fractures in elderly patients remains a subject for debate. Our aim was to review randomised controlled trials to establish which type provides superior clinical outcome for this patient population.

Methods

We searched PubMed, Embase and Cochrane Register of Controlled Trials databases and Web of Science for randomised controlled trials (RCTs) comparing unipolar with bipolar HA to treat femoral-neck fracture in the elderly. Risk ratios (RRs) and mean differences (MDs) from each trial were pooled using random-effects or fixed-effects models depending on study heterogeneity. Analysis was performed using RevMan5.2 from the Cochrane Collaboration.

Results

A total of 1,100 patients from nine studies were assessed in this meta-analysis. Results showed no significant differences in function score [MD = −0.14, 95% confidence interval (CI) −2.42–2.13], mortality (RR = 0.97, 95% CI 0.65–1.46), dislocation (RR = 1.33, 95 % CI 0.53–3.34), deep infection (RR = 0.79, 95 % CI 0.35–1.79), acetabular erosion (RR = 1.99, 95 % CI 0.61–6.52), operating time (MD = 2.14, 95 % CI −9.85 to14.14), blood loss (MD = 13.40, 95 % CI −49.60 to 76.39) and length of hospital stay (MD = 0.12, 95 % CI −0.49to0.73) between unipolar and bipolar HA.

Conclusions

Unipolar and bipolar HA achieved similar clinical outcomes in patients with displaced femoral-neck fractures.     

Posterior acetabular arc angle of the femoral head assesses instability of posterior fracture-dislocation of the hip

Purpose

Unstable posterior fracture-dislocation of the hip is determined by the wall defect or acetabular fracture index. The unstable hip is a result of inadequate posterior acetabular coverage of the femoral head from the posterior acetabular wall fracture. In order to measure total posterior acetabular coverage of the femoral head and avoid using the contralateral acetabulum as a calculation reference, the posterior acetabular arc angle of the femoral head was measured to assess stability of posterior fracture-dislocation of the hip.

Methods

Using coronal computed tomography (CT) scan of the normal contralateral acetabulum at the level of the widest acetabular diameter and thinnest medial wall of 60 acetabular fractures, posterior acetabular arc angles of the femoral head in intact, 20 % and 50 % defects of posterior acetabular walls were measured. The angles were measured from the acetabular centre to the thinnest medial wall and to the top, inner cortex of 80 % and 50 % posterior acetabular walls.

Results

Average intact, 80 % and 50 % posterior acetabular walls were 33.82 ± 4.30, 26.88 ± 3.33 and 16.91 ± 2.15 mm which corresponded to 92.25 ± 11.34, 77.42 ± 10.04 and 50.63 ± 6.58° of posterior acetabular arc angles of the femoral head. The intraclass correlation coefficient (ICC) of the measurements including correlation of conversion of posterior acetabular wall depths to posterior acetabular arc angles of the femoral head were more than 0.82 and 0.89.

Conclusions

The measurement technique of posterior acetabular arc angle of the femoral head has strong reliability. Therefore, stable or unstable posterior fracture-dislocation of the hip can be determined in terms of more than 77 degrees or less than 50 degrees of posterior acetabular arc angles of the femoral head instead of less than 20 % or more than 50 % posterior acetabular wall defect.     

Unipolar hemiarthroplasty versus bipolar hemiarthroplasty in the most elderly patients with displaced femoral neck fractures: a randomised, controlled trial

Purpose  

Hemiarthroplasty (HA) is generally considered to be the treatment of choice in the most elderly patients with a displaced fracture of the femoral neck. However, there is inadequate evidence to support the choice between unipolar HA or bipolar HA. The primary aim of this study was to analyse the outcome regarding hip function and health-related quality of life (HRQoL) in patients randomised to either a unipolar or bipolar HA. The secondary aim was to analyse the degree of acetabular erosion and its influence upon outcome.     

The Conversion Rate of Bipolar Hemiarthroplasty after a Hip Fracture to a Total Hip Arthroplasty

Background

Bipolar hip hemiarthroplasty is used in the management of fractures of the proximal femur. The dual articulation is cited as advantageous in comparison to unipolar prostheses as it decreases acetabular erosion, has a lower dislocation rates and is easier to convert to a total hip arthroplasty (THA) should the need arise. However, these claims are debatable. Our study examines the rate of conversion of the bipolar hemiarthroplasty to THA and the justification for using it on the basis of future conversion to THA.

Methods

All cases of bipolar hemiarthroplasty performed in our unit for hip fractures over a 9-year period (1999-2007) were reviewed. Medical notes and radiographs of all patients were reviewed, and all surviving patients that were contactable received a telephone follow-up.

Results

Of all 164 patients reviewed with a minimum of 1 year from date of surgery, 4 patients had undergone a conversion of their bipolar prosthesis to THA. Three conversions were performed for infection, dislocation, and fracture. Only one (0.6%) conversion was performed for groin pain.

Conclusions

Our study show that bipolar hemiarthroplasties for hip fractures have a low conversion rate to THAs and this is comparable to the published conversion rate of unipolar hemiarthroplasties.     

Total hip arthroplasty versus hemiarthroplasty for displaced femoral neck fractures in the healthy elderly: a meta-analysis and systematic review of randomized trials

Purpose

Displaced femoral neck fractures in healthy elderly patients have traditionally been managed with hemiarthroplasty (HA). Recent data suggest that total hip arthroplasty (THA) may be a better alternative.

Methods

A systematic review of the English literature was conducted. Randomized controlled trials comparing all forms of THA with HA were included. Three authors independently extracted articles and predefined data. Results were pooled using a random effects model.

Results

Eight trials totalling 986 patients were retrieved. After THA 4 % underwent revision surgery versus 7 % after HA. The one-year mortality was equal in both groups: 13 % (THA) versus 15 % (HA). Dislocation rates were 9 % after THA versus 3 % after HA. Equal rates were found for major (25 % in THA versus 24 % in HA) and minor complications (13 % THA versus 14 % HA). The weighted mean of the Harris hip score was 81 points after THA versus 77 after HA. The subdomain pain of the HHS (weighted mean score after THA was 42 versus 39 points for HA), the rate of patients reporting mild to no pain (75 % after THA versus 56 % after HA) and the score of WOMAC (94 points for THA versus 78 for HA) all favored THA. Quality of life measured with the EQ-5D favored THA (0.69 versus 0.57).

Conclusions

Total hip arthroplasty for displaced femoral neck fractures in the fit elderly may lead to higher patient-based outcomes but has higher dislocation rates compared with hemiarthroplasty. Further high-quality randomized clinical trails are needed to provide robust evidence and to definitively answer this clinical question.     

Does total hip arthroplasty restore native hip anatomy? Three-dimensional reconstruction analysis

Purpose

Component orientations and positions in total hip arthroplasty (THA) are important parameters in restoring hip function. However, measurements using plain radiographs and 2D computed tomography (CT) slices are affected by patient position during imaging. This study used 3D CT to determine whether contemporary THA restores native hip geometry.

Methods

Fourteen patients with unilateral THA underwent CT scan for 3D hip reconstruction. Hip models of the nonoperated side were mirrored with the implanted side to quantify the differences in hip geometry between sides.

Results

The study demonstrated that combined hip anteversion (sum of acetabular and femoral anteversion) and vertical hip offset significantly increased by 25.3° ± 29.3° (range, −25.7° to 55.9°, p = 0.003) and 4.1 ± 4.7 mm (range, −7.1 to 9.8 mm, p = 0.009) in THAs.

Conclusions

These data suggest that hip anatomy is not fully restored following THA compared with the contralateral native hip.     

Ten year results of the collum femoris preserving total hip replacement: a prospective cohort study of seventy five patients

Purpose

The collum femoris preserving (CFP) uncemented prosthesis has a bone-preserving, high subcapital neck resection and a short anatomical stem. The ideal arthroplasty option in the younger, active patient is a subject of some debate. We evaluated midterm outcomes of the CFP in this patient population.

Methods

A prospective, consecutive cohort of 75 CFP total hip replacement (THR) patients with a mean age of 52 years was followed for a mean of 9.3 years. Patients were assessed using the Harris Hip Score (HHS). Pain was assessed using a visual analogue scale (VAS) and activity levels using the University of California, Los Angeles (UCLA) score. Radiographs were evaluated for evidence of loosening. Survivorship was calculated with an endpoint of revision for aseptic loosening or radiographic evidence of loosening.

Results

Mean HHS improved from a mean of 50 pre-operatively to 91 (p < 0.001) postoperatively. Mean pain score was 1, mean patient satisfaction was 9 and mean UCLA score was 6. Two acetabular components were revised for aseptic loosening; no stem required revision. Radiographically, no cases had evidence of loosening. Survivorship was 96.8 % for the acetabular component and 100 % for the stem at ten years. Three patients died from unrelated causes, and five were lost to follow-up.

Conclusions

Bone-preserving hip replacement has increased in popularity as hip replacement in younger and more active individuals increases. The CFP prosthesis has excellent midterm clinical function and survival and provides high levels of satisfaction in young patients.     

Dual mobility cup reduces dislocation and re-operation when used to treat displaced femoral neck fractures

Purpose

Total hip arthroplasty (THA) as primary treatment for displaced femoral neck fractures is controversial as THA is associated with higher rates of dislocation but lower rates of re-operation compared to hemiarthroplasty (HA). A dual mobility cup (DMC) design is associated with lower dislocation and re-operation rates in elective surgery. Is this also the case when used to treat displaced femoral neck fractures? The aim of this study is to compare rates of dislocation and re-operation of any kind following treatment for displaced femoral neck fractures with either bipolar HA or THA with DMC.

Methods

Two consecutive groups of patients treated for displaced femoral neck fractures at the Regional Hospital in Viborg in Denmark were included. In 2007–2008 171 patients (mean age 84.1 years) were treated with bipolar HA. In 2009–2010 175 patients (mean age 75.2 years) were treated with THA with DMC. Data regarding rates of dislocation and re-operation were obtained by retrospective review of medical records.

Results

We found a statistically significant difference regarding rates of dislocation and re-operation of any kind in favour of THA with DMC. Dislocation occurred in 25/171 patients [95 % confidence interval (CI) 9.3–19.9 %] treated with bipolar HA and 8/175 patients (95 % CI 1.5–7.7 %) treated with THA with DMC (p = 0.002). Re-operations were required in 32/171 patients (95 % CI 12.9–24.6 %) treated with bipolar HA and 16/175 patients (95 % CI 4.8–13.4 %) treated with THA with DMC (p = 0.01).

Conclusions

Our findings indicate that THA with DMC is superior to bipolar HA following treatment for displaced femoral neck fractures in regard to rates of dislocation and re-operation.     

Effect of Pelvic Osteotomy in the Skeletally Immature on Acetabular Coverage

Background

Although pelvic osteotomy in children has been effective in re-establishing containment of the hip joint, its impact on hip joint development with respect to acetabular coverage is ill defined.

Purpose

The purpose of this study is to determine the prevalence of acetabular overcoverage in patients who had pelvic osteotomy during childhood and its impact on patient function.

Patients and Methods

Between 1980 and 2008, all patients who had a pelvic osteotomy done at our institution for non-neuropathic hip dysplasia (DDH) or secondary to Legg–Calvé–Perthes disease (LCP) prior to skeletal maturity were reviewed. A clinical assessment and the WOMAC, UCLA Activity Score, Marx activity score, and SF-36 quality-of-life questionnaires were completed. A standardized AP pelvic X-ray was performed to determine the acetabular coverage, signs of retroversion, and degenerative changes.

Results

Twenty-eight patients (32 hips) were identified, of which 14 (9 DDH, 5 LCP) agreed to participate. Impingement sign was positive in eight patients (six DDH, two LCP). Crossover and ischial spine signs were each present in ten hips. Tonnis grades were: 0 in 1 hip, 1 in 10 hips, 2 in 2 hips, and 3 in 1 hip. The mean Tonnis angle was 11.6 ± 8.6°. The mean CE angle was 24.0 ± 15.9° with six hips having a CE angle <20° and one hip with a CE angle >40°. There was no correlation between crossover sign or ischial sign and Tonnis grade (p = 0.739), hip pain (p = 0.520), or impingement sign (p = 1.00).

Conclusions

Acetabular overcoverage is common in patients who underwent pelvic osteotomy during childhood. No correlation was identified between retroversion and hip pain in our patient cohort.     

Total hip arthroplasty with acetabular reconstruction using a bulk autograft for patients with developmental dysplasia of the hip results in high loosening rates at mid-term follow-up

Purpose

Managing a deficient acetabulum in patients with developmental dysplasia of the hip (DDH) can be challenging. The purpose of the study was to determine the mid-term results of total hip arthroplasty (THA) using a bulk structural autograft for reconstruction of the acetabular roof in patients with DDH.

Methods

Between 1982 and 1999, 112 patients underwent THA with acetabular roof-plasty using a bulk structural autograft for secondary osteoarthritis related to DDH. A total of 106 patients (115 hips) met inclusion criteria and were followed for an average of 11.6 years (seven to 24 years). The mean age was 52.5 years at the index operation. Clinical and radiological evaluations were performed according to the methods of Merle d’Aubigné and Postel, Johnston et al. and DeLee and Charnley.

Results

The overall Merle d’Aubigné hip score significantly improved (3.7 vs 10.4, p < 0.01). The limb length discrepancy decreased from 30 to 6 mm (p < 0.01). The average distance that the hip centre was distalised was 22.3 mm (0–56 mm). However, radiolucent lines were observed in 27 % of patients at final follow-up, and the overall rate of revision for aseptic loosening was 16 %. Further, Kaplan-Meier survivorship curves predicted a rapid increase in the failure rate at 15 years.

Conclusions

The mid-term functional outcome of THA with an acetabular roof-plasty using a bulk autograft is satisfactory; however, the long-term results are questionable.     

Does stem design influence component positioning in total hip arthroplasty using a minimal invasive posterolateral approach?

Purpose

Limited data exist for the reconstructive potential of short bone-preserving stems in THA using a minimal invasive posterolateral approach. Our study aim was to assess the effect of stem design on the reconstruction of hip offset and leg length in MIS posterolateral THA.

Methods

This retrospective consecutive single-surgeon study compares hip offset and leg length, as well as acetabular component positioning (cup anteversion; inclination) of 129 THAs with a cementless standard-length stem (Synergy®) and 143 THAs with a cementless short bone-preserving stem (Trilock®).

Results

In reference to the contralateral side, the mean difference in hip offset was 0.9 mm (p = 0.067) for the standard stem and 0.1 mm (p = 0.793) for the short stem, respectively. Leg-length discrepancy was 0.7 mm (Synergy®) and 0.9 mm (Trilock®), respectively. A total of 233 (86 %) acetabular components fell within the target zone for anteversion and inclination.

Conclusion

Accurate component positioning in MIS posterolateral approach THA is possible and is not influenced by the type of stem.     

Posterior acetabular arc angle of unstable posterior hip fracture–dislocation

Purpose

Posterior hip fracture–dislocation needs stability evaluation. A previous study in the normal acetabulum has shown that the coronal posterior acetabular arc angle (PAAA) could be used to assess an unstable posterior hip fracture. Our study was designed to assess PAAA of unstable posterior hip fracture–dislocation and whether posterior acetabular wall fracture involves the superior acetabular dome.

Methods

Using coronal computed tomography (CT) of the acetabulum and 3D reconstruction of the lateral pelvis, we measured coronal, vertical PAAA and posterior acetabular wall depth of 21 unstable posterior hip fracture–dislocations and of 50 % normal contralateral acetabula. Posterior acetabular wall fracture was assessed to determine whether the fracture involved the superior acetabular dome and then defined as a high or low wall fracture using vertical PAAA in reference to the centroacetabulo–greater sciatic notch line.

Results

The coronal PAAA of unstable posterior hip fracture–dislocations and of 50 % of the posterior acetabular wall of normal the contralateral acetabulum were 54.48° (9.09°) and 57.43° (5.88°) and corresponded to 15.06 (4.39) and 15.61 (2.01) mm of the posterior acetabular wall without significant difference (p > 0.05). The vertical PAAA of unstable posterior hip fracture–dislocation was 101.67° (20.44°). There were 16 high posterior acetabular wall fractures with 35.00 (16.18) vertical PAAA involving the acetabular dome and 5 low wall fractures. High posterior wall fractures resulted in four avascular necroses of the femoral head, three sciatic nerve injuries and one osteoarthritic hip.

Conclusion

Coronal and vertical PAAA of unstable posterior hip fracture–dislocations were 54.48° and 101.67°. Vertical PAAA assesses high or low posterior acetabular wall fracture by referring to the centroacetabulo–greater sciatic notch line. High posterior wall fracture seems to be the most frequent and is involved with many complications.     

The natural history of unexplained early poor function following total hip replacement

Purpose

The majority of patients experience a significant improvement in quality of life and function after total hip replacement (THR). It has recently been shown that age and good pre-operative function are the best predictors of postoperative function. When patients fail to achieve a satisfactory outcome, a cause is often identified. Where there is no identifiable cause, advice, follow-up and management is not clear. The aim of this study was to determine the long-term outcome of patients who had early poor function, but no identifiable cause.

Methods

From a regional database, we identified 1,564 patients who underwent unilateral THR between 1998 and 2004 and who were without complication or subsequent bilateral procedure at six months. These patients were divided into two groups according to their Harris hip score (HHS) at this stage: group A consisted of 270 patients with a ‘poor’ result (HHS less than 70). Group B consisted of 1,294 patients with a ‘good’ or ‘excellent’ result (HHS 70 or above). The patients were reviewed at five years. One hundred and ten patients from group A and 980 from group B completed five-year follow-up without further identifiable complication.

Results

Those with poor or fair function at six months were at an increased risk of developing an identified complication by five years including dislocation (OR 5.7, 95 % CI 1.8–18.2), deep infection (OR 9.8, 95%CI 2.9–37.7) and death (OR 1.6, 95 % CI 1.1–2.3). There was a greater rate of revision in group A versus group B (OR 5.7, 95 % CI 2.9–11). The overall function measured by the Harris hip score significantly improved in group A, but never reached that of those with good or excellent function at six months (HHS 76.2 versus 90.3, P < 0.001).

Conclusions

Patients with poor function at six months, but no obvious cause, are at higher risk of developing complications by five years. This group may benefit from more regular arthroplasty review and intervention.     

A new method of measuring acetabular cup anteversion on simulated radiographs

Purpose

Optimal positioning of acetabular components is crucial for maintaining stability of THA. Postoperative assessment of acetabular anteversion is a vital but difficult task. Various methods have been devised with good results for measuring anteversion on plain radiographs but these methods are either too complicated or require special objects like scientific calculators, special protectors, tables, etc. A new simplified method of measuring anteversion on plain radiographs was created based on basic geometry.

Methods

Anteversion of acetabular components was estimated on computer generated images of the acetabular cup by our method and compared with two previously established methods of Liaw and Pradhan. Measurement was done at 400 different positions of acetabular cup and compared with actual values. Another analysis was done after adding the femoral head to the acetabular component, thus obscuring some of the acetabular rim.

Results

Mean and standard deviation of error for our method was 0.77° ± 0.75° as compared to 0.93° ± 0.86° and 0.72° ± 0.68° for the methods of Liaw and Pardhan, respectively, with no significant differences from actual values. Maximal errors for our method, Liaw’s and Pradhan’s method were 3°, 4°, and 2.91°, respectively. On analysis, after the adding femoral head, there was a significant error of measurement with Liaw’s method, while our method as well as Pardhan’s remained accurate. All methods showed high inter- and intraobserver reliability.

Conclusion

Our new simplified method of measuring acetabular anteversion on plain radiographs is acceptable in comparision to other established methods and requires only routinely used goniometer and calliper.     

Dorsal versus transgluteal approach for hip hemiarthroplasty: an analysis of early complications in seven hundred and four consecutive cases

Purpose

Hemiarthroplasty (HA) is an established treatment for femoral neck fractures of the elderly. Several surgical approaches are currently used including dorsal and transgluteal. It is still unclear whether one approach may be advantageous. We compared early complication rates after dorsal and transgluteal approaches.

Methods

We retrospectively analysed a cohort including 704 consecutive patients who received HA for femoral neck fracture; 212 male and 492 female patients were included, and the mean age was 80.4 years (SD 9.8 years). In 487 patients a dorsal and in 217 a transgluteal approach was chosen. In all patients an Excia® stem with self-centring bipolar head manufactured by Aesculap (Tuttlingen, Germany) was used. We evaluated early postoperative complications including dislocation, infection, haematoma, seroma and perioperative fracture. Complication rates after dorsal and transgluteal approaches were calculated and compared by the chi-square test.

Results

After a dorsal approach 10.5 % [confidence interval (CI) 7.7–13.2 %] of the patients suffered one or more early complications. Following a transgluteal approach this proportion was 9.7 % (CI 5.7–13.6 %), which was not significantly different (p = 0.75). The predominant complication after a dorsal approach was dislocation (3.9 %; CI 2.2–5.6 %). The dislocation rate after a transgluteal approach was significantly lower (0.5 %; CI 0–1.4 %). Postoperative haematoma however was seen after a transgluteal approach in 5.5 % (CI 2.5–8.6 %), which was significantly more frequent than after a dorsal approach (1.2 %; CI 0.2–2.2 %). The frequency of the other types of complications did not significantly differ.

Conclusions

The rate of early surgical complications after dorsal and transgluteal approaches is not significantly different. However, the dorsal approach predisposed to dislocation, whereas the transgluteal approach predisposed to haematoma.     

Finite Element Analysis Examining the Effects of Cam FAI on Hip Joint Mechanical Loading Using Subject-Specific Geometries During Standing and Maximum Squat

Background:

Cam femoroacetabular impingement (FAI) can impose elevated mechanical loading in the hip, potentially leading to an eventual mechanical failure of the joint. Since in vivo data on the pathomechanisms of FAI are limited, it is still unclear how this deformity leads to osteoarthritis.

Purpose:

The purpose of this study was to examine the effects of cam FAI on hip joint mechanical loading using finite element analysis, by incorporating subject-specific geometries, kinematics, and kinetics.

Questions:

The research objectives were to address and determine: (1) if hips with cam FAI demonstrate higher maximum shear stresses, in comparison with control hips; (2) the magnitude of the peak maximum shear stresses; and (3) the locations of the peak maximum shear stresses.

Methods:

Using finite element analysis, two patient models were control-matched and simulated during quasi-static positions from standing to squatting. Intersegmental hip forces, from a previous study, were applied to the subject-specific hip geometries, segmented from CT data, to evaluate the maximum shear stresses on the acetabular cartilage and underlying bone.

Results:

Peak maximum shear stresses were found at the anterosuperior region of the underlying bone during squatting. The peaks at the anterosuperior acetabulum were substantially higher for the patients (15.2 ± 1.8 MPa) in comparison with the controls (4.5 ± 0.1 MPa).

Conclusions:

Peaks were not situated on the cartilage, but instead located on the underlying bone. The results correspond with the locations of initial cartilage degradation observed during surgical treatment and from MRI.

Clinical Relevance:

These findings support the pathomechanism of cam FAI. Changes may originate from the underlying subchondral bone properties rather than direct shear stresses to the articular cartilage.     

Three dimensional-CT evaluation of femoral neck anteversion, acetabular anteversion and combined anteversion in unilateral DDH in an early walking age group

Purpose

At present, the indications for femoral derotational osteotomy remain controversial due to the inconsistent findings in femoral neck anteversion in developmental dysplasia of the hip (DDH). Moreover, combined anteversion is not assessed in unilateral DDH using three dimensional-CT. Therefore, the purposes of our study were to observe whether the femoral neck anteversion (FA), acetabular anteversion (AA) and combined anteversion (CA) on the dislocated hips were universally presented in unilateral DDH according to the classification system of Tönnis.

Methods

Sixty-two patients with unilateral dislocation of hip were involved in the study, including 54 females and eight males with a mean age of 21.63 months (range, 18–48 months). The FA, AA and CA were measured and compared between the dislocated hips and the unaffected hips.

Results

Although no significant difference was observed in FA between the dislocated hips and the unaffected hips (P = 0.067, 0.132, respectively) in Tönnis II and III type, FA was obviously increased on the dislocated hips compared with the unaffected hips in Tönnis IV type. Increased AA on the dislocated hips was a universal finding in Tönnis II, III and IV types. Meanwhile, a wide safe range of CA from 24° to 62° was demonstrated on the unaffected hips.

Conclusion

Femoral derotational osteotomy seems not to be necessary in Tönnis II and III types in unilateral DDH. Femoral derotational osteotomy should be considered in DDH, especially in Tönnis IV type, if the CA is still above 62° and the hip joints present instability in operation after abnormal acetabular anteversion, acetabular index and acetabular coverage of the femoral head are recovered to normal range through pelvic osteotomy.     

Cross-sectional Anatomy of the Ilium: Implications for Acetabular Component Placement in Total Hip Arthroplasty

Background

High hip center reconstructions, used in revision and complex primary THAs, rely on pelvic bone stock at least 35 mm above the anatomic teardrop. However, the technique does not restore normal hip biomechanics and controversy exists regarding acetabular implant survival. Previous reports document a wide range of implant positioning above the teardrop. There is no anatomic guidance in the literature regarding the amount of bone stock available for initial implant stability in this area of the ilium.

Questions/purposes

We therefore determined the thickness of the human ilium and related it to acetabulum cup coverage in high hip center reconstructions.

Methods

We sectioned 16 cadaveric hips from the anterior superior iliac spine to the anatomic teardrop in 5-mm increments, then measured the thickness of the ilium for each cross section.

Results

The maximum thickness of 42 ± 9 mm occurred at the dome of the acetabulum 35 ± 3 mm above the teardrop. At a distance of 1 cm above the dome, the ilium was reduced by 24%, to 32 ± 6 mm. At 2 cm above the dome, the ilium thickness was 22 ± 4 mm, a 48% reduction from its maximum.

Conclusion

There are substantial anatomic limitations to high hip reconstructions 2 cm above the acetabular dome.