How to Screen for Lumbar Spine Stiffness in Patients Awaiting Total Hip Arthroplasty.

BACKGROUND: This study aimed to (1) define the prevalence of spinopelvic abnormalities among patients who have hip osteoarthritis (OA) and controls (asymptomatic volunteers) and (2) identify factors that reliably predict the presence of lumbar spine stiffness. METHODS: This is a prospective, cross-sectional, case-cohort study of patients who have end-stage primary hip OA, who underwent primary total hip arthroplasty (THA). Patients were compared with a cohort of asymptomatic volunteers, matched for age, sex, and body mass index (BMI), serving as a control group. Spinopelvic pathologies were defined as: lumbar spine flatback deformity (difference of 10 or more degrees for pelvic incidence minus lumbar lordosis angle), a standing sagittal pelvic tilt of 19° or more and lumbar spine stiffness (lumbar flexion of less than 20° between both postures). RESULTS: The prevalence of spinopelvic pathologies was similar between patients and controls (flatback deformity: 16% versus 10%, P = .209; standing pelvic tilt >19°: 17% versus 24%, P = .218; lumbar spine stiffness: 6% versus 5%, P = .827). Age over 65 years-old and standing lumbar lordosis angle less than 45° were associated with high sensitivity and specificity for identifying lumbar spine stiffness (age >65 years: 82% and 66%; standing lumbar lordosis angle <45°: 85% and 73%). CONCLUSION: The presence of end-stage hip osteoarthritis was not associated with increased prevalence of adverse spinopelvic characteristics compared to matched, asymptomatic volunteers. Age and LLstanding are the strongest predictors of lumbar spine flexion and can guide clinical practice on when to obtain additional radiographs for patients who have hip OA before arthroplasty to identify at-risk patients. LEVEL OF EVIDENCE: II (prospective, cohort study).

Elevated Blood Tantalum Concentrations in Patients Following Reconstruction of Severe Acetabular Defects in Total Hip Arthroplasty Using Modular Tantalum Augments in Combination With Uncemented Tantalum Cups.

INTRODUCTION: The reconstruction of acetabular defects in total hip arthroplasty (THA) can be challenging. An option to treat uncontained acetabular defects is to use modular tantalum augments in combination with cementless press-fit cups. However, modularity is associated with an increased risk of debonding and mechanical failure. In addition, metal wear particles can be released due to micromotions at the implant interface. Clinical data on the long-term results of this treatment strategy is limited. The purposes of this study were: (1) to evaluate the clinical and radiological outcome of complex THA using modular trabecular metal augments and uncemented revision cups; (2) to investigate the blood tantalum concentrations in these patients at mid-term (mean 4.5 year) follow-up; and (3) to report complications and mechanisms of failure related to this procedure. MATERIALS AND METHODS: In this single-center study, we retrospectively reviewed data from a consecutive cohort of 27 patients who underwent complex acetabular defect reconstruction using a modular tantalum acetabular augment in combination with an uncemented tantalum cup. We evaluated the implant survival, and the radiological and clinical outcomes after a mean follow-up of 4.5 years (SD 2.1; range 2.5 to 10.6 years) using patient-reported outcome scores (PROMs). Blood samples were analyzed regarding tantalum concentration and compared with a control group. RESULTS: The cumulative survival rate at 4.5 years with the endpoint "revision of the acetabular component for aseptic loosening" was 94.4% (95% confidence interval (CI) 71.6 to 99.2) and 82.9% (95 % CI 60.5 to 93.3) for the endpoint "revision for any reason." The PROMs improved significantly up to the latest follow-up, and radiographic data showed no signs of loosening or implant migration. Median blood tantalum concentrations were significantly higher in the study group (0.15 µg/L) compared to the control group (0.002 µg/L) (P < 0.001). CONCLUSIONS: This study demonstrated acceptable clinical and radiological results of cementless revision THA using modular trabecular metal implants for the reconstruction of large acetabular defects. Tantalum concentrations were significantly higher in patients who had tantalum implants compared to the control group, however, the systemic and local effects of an increased tantalum exposure are not yet fully understood and have to be further investigated.

How Do Spinopelvic Characteristics Change Post-Total Hip Arthroplasty? A Longitudinal Assessment Raising Awareness of the Postoperative Period.

BACKGROUND: Spinopelvic characteristics, including sacral slope (SS), are commonly evaluated in different positions pre-total hip arthroplasty (THA). This study aimed to: 1) investigate the change in spinopelvic parameters at 7 days (early) and 1-year post-THA; and 2) identify patient characteristics associated with a change in SS of more than 7° post-THA. METHODS: We prospectively studied 250 patients who underwent unilateral THA [132 women, age 66 years (range, 32 to 88)] and underwent biplanar images preoperatively and at 7 days and 1-year post-THA. Parameters measured included pelvic incidence, standing lumbar lordosis, SS, and proximal femoral angle (PFA). A SS change ≥ 7° was considered the threshold as it would result in more than a 5° change in cup orientation. RESULTS: Early post-THA SSstanding remained within ± 6º from preoperative measurements in 75% of patients, reduced by ≥ 7° in 9%, and increased by ≥ 7° in 16%. Those that showed a reduction in SS had the lowest PFA and the highest SS pre-THA (P = .028, .107, and < 0.001, respectively). From 7 days until the 1-year mark, pelvic tilt increased, SS reduced (mean: -4º, range: -29 to 17º, P < .001), and patients stood with greater hip extension ΔPFAstanding (mean 7°, range: -34 to 37°, P < .001). At 1 year, SSseated had remained within ± 6º, relative to the pre-THA value, in 49% of patients. CONCLUSIONS: Standing spinopelvic characteristics, especially SSstanding, remain within ±6° in three-quarters of patients both early- and at 1-year post-THA. In the remaining cases, pelvic tilt changes significantly. In 9% of cases, SS reduces ≥ 7° early THA, probably due to the alleviation of fixed-flexion contractures. The SSseated changes by ≥ ± 7° in almost 50% of cases in this study, and its clinical value as a preoperative planning tool should be questioned. LEVEL OF EVIDENCE: Level II, diagnostic study.

Impact of Offset and Leg Length on Functional Outcomes Post-Total Hip Arthroplasty: How Accurate Should Coronal Reconstruction Be?

BACKGROUND: Accurate hip reconstruction is associated with improved biomechanical behavior following total hip arthroplasty (THA). However, whether this is associated with improved patient-reported outcomes (PROs) is unknown. HYPOTHESIS/PURPOSE: This study aimed to: 1) describe the ability to reconstruct coronal geometry during THA without advanced technology; 2) assess whether restoration of global offset (GO) and leg length (LL) is associated with improved PROs; and 3) investigate whether increased femoral offset (FO) to compensate for reduced acetabular offset (AO) influences PROs. METHOD: This was a prospective, multicenter, consecutive cohort study of 500 patients treated with primary THA without robotics or navigation. The Oxford Hip score (OHS) was obtained preoperatively and at 1-year follow-up. Supine anteroposterior pelvic radiographs were analyzed to determine AO, FO, GO, and LL relative to the native contralateral side. Contour plots for ΔOHS based on ΔLL and ΔGO were created, and ΔOHS was calculated within and outside various ranges (±2.5, ±5, or ±10 mm). RESULTS: In the operated hip, mean FO increased by 3 ± 6 mm (range, -16 to 27), while AO decreased by 2 ± 4 mm (range, -17 to 10). The contour graph for ±2.5 mm zones showed the best outcomes (ΔOHS >25) with GO and LL centered on 0 ± 2.5 mm (P < .01). However, only 10% achieved such reconstruction. When GO and LL differences were within ±10 mm, ΔOHS was superior when both AO and FO were within ±5 mm (mean: 24 ± 10; range, -5 to 40) compared with when FO was above 5 mm to compensate for a reduction in AO (mean: 22 ± 11; range, -10 to 46; P = .040). CONCLUSIONS: The PROs were associated with biomechanical reconstruction, and the best clinical improvement can be expected when GO and LL differences are both within 2.5 mm. Maintenance of AO is important, as compensation by increasing FO is associated with inferior OHS.

Change in cup orientation from supine to standing posture: a prospective cohort study of 419 total hip arthroplasties.

BACKGROUND AND PURPOSE: Arthroplasty surgeons traditionally assess cup orientation after total hip arthroplasty (THA) on supine radiographs. Contemporary hip-spine analyses provide information on standing, functional cup orientation. This study aims to (i) characterize cup orientations when supine and standing; (ii) determine orientation differences between postures; and (iii) identify factors associated with magnitude of orientation differences. METHODS: This is a 2-center, multi-surgeon, prospective, consecutive cohort study. 419 primary THAs were included (57% women; mean age: 64 years, standard deviation [SD] 11). All patients underwent supine and standing antero-posterior pelvic and lateral spinopelvic radiographs. Cup orientation and spinopelvic parameters were measured. Target cup orientation was defined as inclination/anteversion of 40°/20° ± 10°. A change in orientation (Δinclination/Δanteversion) between postures > 5° was defined as clinically significant. Variability was defined as 2 x SD. RESULTS: Inclination increased from 40° (supine) to 42° (standing) corresponding to a Δinclination of 2° (95% confidence interval [CI] 2-3). Anteversion increased from 25° (supine) to 30° (standing) corresponding to a Δanteversion of 5° (CI 5-6). When supine, 69% (CI 65-74) of THAs were within target, but only 44% (CI 39-49) were within target when standing, resulting in a further 26% (CI 21-30) being out of target when standing. From supine to standing, a clinically significant change in anteversion (> 5°) was seen in 47% (CI 42-52) of cases. Δanteversion was higher in women than in men (6°, CI 5-7 vs 5°, CI 4-5) corresponding to a difference of 1° (CI 1-2), which was dependent on tilt change, standing cup anteversion, age, and standing pelvic tilt. CONCLUSION: Cup inclination and version increase upon standing but significant variability exists due to patient factors.

How is hip anatomy reconstruction and inlay wear associated up to 10 years after primary THA using ceramic on highly crosslinked polyethylene bearings?

INTRODUCTION: Conventional polyethylene (PE) wear has been reported to be associated with femoral offset reconstruction and cup orientation after THA. Thus, the present study aimed (1) to determine the polyethylene wear rate of 32 mm ceramic heads with highly cross-linked polyethylene (HXLPE) inlays up to 10 years postoperatively and (2) to identify patient and surgery-related factors affecting the wear rate. METHODS: A prospective cohort study was performed, investigating 101 patients with 101 cementless THAs and ceramic (32 mm) on HXLPE bearings after 6-24 months, 2-5 years and 5-10 years postoperatively. The linear wear rate was determined using a validated software (PolyWare®, Rev 8, Draftware Inc, North Webster, IN, USA) by two reviewers, blinded to each other. A linear regression model was used to identify patient and surgery-related factors on HXLPE -wear. RESULTS: After an initial bedding-in phase of 1 year after surgery, the mean linear wear rate was 0.059 ± 0.031 mm/y at ten years (mean 7.7 years; SD 0.6 years, range 6-10), being below the osteolysis relevant threshold of 0.1 mm/year. The regression analysis demonstrated that age at surgery, BMI, cup inclination or anteversion and the UCLA score were not associated with the linear HXLPE-wear rate. Only increased femoral offset showed a significant correlation with an increased HXLPE-wear rate (correlation coefficient of 0.303; p = 0.003) with a moderate clinical effect size (Cohen's f²=0.11). CONCLUSION: In contrast to conventional PE inlays, hip arthroplasty surgeons may be less concerned about osteolysis-related wear of the HXLPE if the femoral offset is slightly increased. This allows focusing on joint anatomy reconstruction, hip stability and leg length.

Fixed-bearing is superior to mobile-bearing in lateral unicompartmental knee replacement: a retrospective matched-pairs analysis.

PURPOSE: Due to low incidence of isolated lateral osteoarthritis (OA), there are limited data on whether a fixed-bearing (FB) or a mobile-bearing (MB) design is superior for lateral unicompartmental knee replacement (UKR). The aim of this matched-pairs analysis was to compare both designs in terms of implant survival and clinical outcome. METHODS: Patients who received MB-UKR (Group A) and FB-UKR (Group B) at a single centre were matched according to gender, age at time of surgery and body mass index (BMI). Survivorship analysis was performed with the endpoint set as "revision for any reason". Clinical outcome was assessed using the Oxford knee score (OKS), visual analogue scale for pain (VAS), patients' satisfaction, University of California Los Angeles activity scale (UCLA) and the Tegner activity score (TAS). RESULTS: A total of 60 matched pairs were included with a mean follow-up (FU) of 3.4 ± 1.3 (range 1.2-5.0) years in Group A and 2.7 ± 1.2 (range 1.0-5.0) years in Group B. Survivorship between both groups differed significantly (Group A: 78.7%; Group B: 98.3%, p = 0.003) with bearing dislocation being the most common reason for revision in Group A (46.2%). The relative and absolute risk reduction were 92.2% and 20%, respectively, with 5 being the number needed to treat. There were no differences in OKS (Group A: 41.6 ± 6.5; Group B: 40.4 ± 7.7), VAS (Group A: 2.9 ± 3.2; Group B: 1.6 ± 2.2), UCLA (Group A: 5.7 ± 1.3; Group B: 5.9 ± 1.8) and TAS (Group A: 3.0 ± 1.0; Group B: 3.1 ± 1.2) between both groups on follow-up. CONCLUSION: Despite modern prosthesis design and surgical technique, implant survival of lateral MB-UKR is lower than that of FB-UKR on the short- to mid-term due to bearing dislocation as the most common cause of failure. Since clinical results are equivalent in both groups, FB-UKR should be preferred in treatment of isolated lateral OA. LEVEL OF EVIDENCE: Retrospective case-control study, Level III.

Sacral Slope Change From Standing to Relaxed-Seated Grossly Overpredicts the Presence of a Stiff Spine.

BACKGROUND: Several authors propose that a change in sacral slope of ≤10° between the standing and relaxed-seated positions (ΔSSstanding→relaxed-seated) identifies a patient with a stiff lumbar spine and has suggested the use of dual-mobility bearings for such patients undergoing a total hip arthroplasty (THA). The aim of this study was to assess how accurately ΔSSstanding→relaxed-seated can identify patients with a stiff spine. METHODS: A prospective, multicentre, consecutive cohort series of 312 patients had standing, relaxed-seated, and flexed-seated lateral radiographs prior to THA. ΔSSstanding→relaxed-seated was determined by the change in sacral slope between the standing and relaxed-seated positions. Lumbar flexion (LF) was defined as the difference in lumbar lordotic angle between standing and flexed-seated. LF ≤20° was considered a stiff spine. The predictive value of ΔSSstanding→relaxed-seated for characterizing a stiff spine was assessed. RESULTS: A weak correlation between ΔSSstanding→relaxed-seated and LF was identified (r2 = 0.13). Eighty six patients (28%) had ΔSSstanding→relaxed-seated ≤10° and 19 patients (6%) had a stiff spine. Of the 86 patients with ΔSSstanding→relaxed-seated ≤10°, 13 had a stiff spine. The positive predictive value of ΔSSstanding→relaxed-seated ≤10° for identifying a stiff spine was 15%. CONCLUSION: In this cohort, ΔSSstanding→relaxed-seated ≤10° was not correlated with a stiff spine. Using this simplified approach could lead to a 7-fold overprediction of patients with a stiff lumbar spine and abnormal spinopelvic mobility, unnecessary use of dual-mobility bearings, and incorrect component alignment targets. Referring to patients with ΔSSstanding→relaxed-seated ≤10° as being stiff is misleading. The flexed-seated position should be used to effectively assess a patient's spine mobility prior to THA.

Minimally invasive Oxford medial unicompartmental knee replacement in patients 50 years of age or younger.

INTRODUCTION: The aim of the present study was to assess clinical outcome and mid-term survivorship of mobile-bearing unicompartmental knee arthroplasty in patients 50 years of age or younger. METHODS: This study reports the results of 119 patients (130 knees) following mobile-bearing medial UKA. Primary indication was advanced osteoarthritis or avascular necrosis of the femoral condyle. The anterior cruciate ligament (ACL) as well as the collateral ligaments were functionally intact, the varus deformity was manually correctable and there was no evidence of osteoarthritis in the lateral compartment. Survivorship analysis was performed with different endpoints and clinical outcome was measured using the Oxford Knee Score (OKS), American Knee Society Score and Functional Score (AKSS-O, AKSS-F), range of motion (ROM), Tegner activity score, University of California Los Angeles score (UCLA) and visual analogue scale for pain (VAS). RESULTS: The survival rate was 96.6% at 6.5 years (95% CI 98.7-91.3%; number at risk: 56) and 91.7% (95% CI 96.7-80%; number at risk: 22) at 10 years for the endpoint device related revisions and 91.5% at 6.5 years (95% CI 95.4-84.5%; number at risk: 56) and 86.8% (95% CI 93-76.2%; number at risk: 22) at 10 years for the endpoint revision for any reason. Outcome scores, VAS and ROM showed significant improvements (p < 0.001). The mean OKS increased from 26.7 (standard deviation (sd): 7.2) preoperatively to 40.9 (sd: 7.6) at final follow-up, the mean AKSS-O from 48.3 (sd: 13.3) to 87.8 (sd: 14.4) and the mean ROM from 118° (sd: 16.7) to 125° (sd: 11.4). The radiological analysis revealed progression of degenerative changes in the lateral compartment in 39.6% of patients without affecting the functional outcome. CONCLUSIONS: Medial mobile-bearing UKA is a viable surgical treatment option in young patients with significant improvements in knee function and pain. Further follow-up is necessary to evaluate the long-term efficacy. LEVEL OF EVIDENCE: Retrospective cohort study, Level III.

Minimum 20-year follow-up of a press-fit acetabular cup in cementless total hip replacement in young patients.

PURPOSE: We aimed to determine the minimum 20-year survival rates of a cementless press-fit cup in young patients. PATIENTS AND METHODS: This is a retrospective, single-center, multi-surgeon cohort study investigating the minimum 20-year clinical and radiological outcome of the first 121 consecutive total hip replacements (THRs) using a cementless, press-fit cup (Allofit, Zimmer, Warsaw, IN, USA) performed between 1999 and 2001. 28-mm metal-on-metal (MoM) and ceramic-on-conventionally not highly crosslinked polyethylene (CoP) bearings were used in 71% and 28%, respectively. Median patient age at surgery was 52 (range 21-60) years. Kaplan-Meier survival analysis was conducted for different endpoints. RESULTS: The 22-year survival rate for the endpoint aseptic cup or inlay revision was 94% (95% confidence interval [CI] 87-96) and 99% (CI 94-100) for aseptic cup loosening. 20 patients (21 THRs; 17%) had died and 5 (5 THRs; 4%) were lost to follow-up. No THR showed evidence of radiographic cup loosening. Osteolysis was observed in 40% of THRs with MoM and 77% with CoP bearings. 88% of THRs with CoP bearings showed significant polyethylene wear. CONCLUSION: The investigated cementless press-fit cup, which is still in clinical use today, showed excellent long-term survival rates in patients under the age of 60 years at surgery. However, osteolysis due to polyethylene and metal wear was frequently observed and is a matter of concern in the third decade after surgery.

Cup orientation following posterior approach THA - the effect of different visual aids and pelvic supports.

INTRODUCTION: This study aims to compare cup inclination achieved (1) Using two orientation guides, whilst using the same 3-point pelvic positioner and (2) Using two types of pelvic positioners, whilst measuring intra-operative cup inclination with an inclinometer. MATERIALS AND METHODS: This is a prospective, diagnostic cohort study of a consecutive series of 150 THAs performed through a posterior approach. Two types of 3-point pelvic positioners were used (Stulberg and modified Capello Hip Positioners) and the cup was positioned freehand using one of two orientation guides (mechanical guide or digital inclinometer). Intra-operative inclination was recorded, radiographic cup inclination and anteversion were measured from radiographs. The differences in inclination due to pelvic position (ΔPelvicPosition) and orientation definitions (ΔDefinition) were calculated. Target radiographic inclination and anteversion was 40/20° ± 10°. RESULTS: There was no difference in radiographic cup inclination/ (p = 0.63) using a mechanical guide or digital inclinometer. However, differences were seen in ΔPelvicPosition between the positioners ((Stulberg: 0° ± 5 vs. Capello: 3° ± 6); p = 0.011). Intra-operative inclination at implantation was different between positioners and this led to equivalent cases within inclination/anteversion targets (Stulberg:84%, Capello:80%; p = 0.48). CONCLUSIONS: With the pelvis securely positioned with 3-point supports, optimum cup orientation can be achieved with both alignment guides and inclinometer. Non-optimal cup inclinations were seen when intra-operative inclinations were above 40° and below 32°, or the ΔPelvicPosition was excessive (> 15°; n = 2). We would thus recommend that the intra-operative cup inclination should be centered strictly between 30° and 35° relative to the floor. Small differences exist between different type of pelvic positioners that surgeons need to be aware off and account for.

Differences in Spinopelvic Characteristics Between Hip Osteoarthritis Patients and Controls.

BACKGROUND: This study of patients with hip primary osteoarthritis and a matched, asymptomatic, volunteers (controls) group aimed to determine spinopelvic differences between the two groups and their consequences for total hip arthroplasty. METHODS: 104 patients (52 in each group) had their sagittal spinopelvic parameters (lumbar lordosis angle, sacral slope, pelvic tilt, pelvic incidence, and the pelvic-femoral angle) measured in the standing, relaxed-seated, and deep-flexed seated positions. Spinopelvic movement was calculated as the change between the different positions, and individual spinopelvic mobility was classified in accordance with the change in pelvic tilt as previously described (ΔPT: stiff (<10°), normal (10-30°), and hypermobile (>30°)). RESULTS: Transitioning from the standing to relaxed-seated position, patients demonstrated 13˚ less hip flexion (P < .001), 12˚ more posterior pelvic tilt (P = .006), and 6˚ more lumbar flexion (P = .038) compared with controls. Transitioning from the standing to deep-flexed seated position, patients demonstrated 18˚ less hip flexion (P < .001), accompanied by a posterior and not an anterior pelvic tilt as in the controls (7˚ ± 14 vs -6˚ ± 17; P < .001). Patients showed a higher percentage of spinopelvic hypermobility (19% vs 2%; P = .008). CONCLUSION: The reduced ability of flexion in the arthritic hip, leads to posterior pelvic tilt in the relaxed-seated position. This is associated with a likely compensatory increased lumbar flexion to keep an upright position. Therefore, spinopelvic hypermobility has to be defined as pathologic. When moving to the deep-flexed seated position, decreased flexion of the arthritic hip prevents the pelvis from tilting anteriorly while the lumbar spine performs a compensatory flexion by approximately the same amount compared with controls. LEVEL OF EVIDENCE: Level II, diagnostic study.

How Does Spinopelvic Mobility and Sagittal Functional Cup Orientation Affect Patient-Reported Outcome 1 Year after THA?-A Prospective Diagnostic Cohort Study.

BACKGROUND: This prospective cohort study aimed to characterize how spinopelvic characteristics change post-total hip arthroplasty (THA) and determine how patient-reported outcome measures are associated with 1) individual spinopelvic mobility and 2) functional sagittal cup orientation post-THA. METHODS: One hundred consecutive patients who received unilateral THAs for end-stage hip osteoarthritis, without spinal pathology were studied. Preoperatively and postoperatively, patients underwent clinical and radiographic evaluations. Patient-reported outcomes were collected using the hip disability and osteoarthritis outcome score - physical function shortform (HOOS-PS). Radiographic parameters measured from standing and relaxed-seated radiographs, included the lumbar lordosis angle, pelvic tilt, pelvic femoral angle and cup orientation in the coronal (inclination/anteversion) and sagittal (anteinclination) planes. Spinopelvic mobility was characterized (ΔPT: "stiff" [<10°], "normal" [10°-30°], and "hypermobile" [>30°]). RESULTS: Preoperative spinopelvic characteristics were not associated with HOOS-PS. Post-THA, the spinopelvic characteristics changed, with less patients having spinopelvic hypermobility (7%) compared with preop (14%). Postoperatively, patients with spinopelvic hypermobility showed significantly worse HOOS-PS scores (21 ± 17 vs 21 ± 22 vs 41 ± 23; ANOVA P = .037). Sagittal but not coronal cup orientation was associated with postoperative spinopelvic characteristics. Cup anteinclination was less in the patients with postoperative spinopelvic hypermobility (27 ± 7° vs 36 ± 8° vs 36 ± 10°; ANOVA: P = .035). CONCLUSION: We hypothesize that spinopelvic hypermobility is secondary to impingement and reduced hip flexion; to achieve a seated position, impinging hips require more posterior pelvic tilt. Patients with spinopelvic hypermobility are likely impinging secondary to the low cup anteinclination (sagittal malorientation despite optimum coronal orientation) and thus have lower HOOS-PS compared. Sagittal assessments are thus important to adequately study hip mechanics. LEVEL OF EVIDENCE: Level II, diagnostic study.

[What are the benefits of patient-specific reconstruction in total hip replacement?] / Welchen Nutzen hat die Rekonstruktion der patientenindividuellen Anatomie beim endoprothetischen Hüftgelenkersatz?

BACKGROUND: The success of primary total hip replacement (THR) is predominately determined by the primary stability of the implant and the restoration of the patient-specific joint biomechanics. The three-dimensional (patho-) anatomy, size, geometry, and shape of the acetabulum and proximal femur is highly variable in patients with advanced hip osteoarthritis. Accurate preoperative planning is an essential prerequisite for all replacement procedures. CURRENT SITUATION: Current data demonstrates clinical advantages for patient-specific reconstruction of functional joint geometry via surrogate parameters (offset and leg length). Frequently cited "target zones" for the positioning and orientation of the cup are increasingly in the focus of scientific discussion, as individually adjusted target zones for implant positioning allow for a potential reduction of impingement risk. Patients with spinal fusions or pathologic spinopelvic alignment require that particular attention be paid to patient-specific preoperative preparation, the surgical technique, and implant selection in order to reduce the risk of postoperative instability.

What Is the Long-term (27- to 32-year) Survivorship of an Uncemented Tapered Titanium Femoral Component and Survival in Patients Younger Than 50 Years?

BACKGROUND: Uncemented femoral components in primary THA are in widespread use, especially in patients younger than 50 years, but few studies have evaluated their survival into the late third and early fourth decade. QUESTIONS/PURPOSES: We evaluated (1) survivorship using femoral revision for any reason as the endpoint, (2) survivorship using femoral revision for aseptic loosening as the endpoint, (3) survival in patients younger than 50 years, (4) cumulative incidence of stem revision for periprosthetic femoral fracture and (5) the overall risk of revision (change of any part of the implanted components) at a minimum of 27 years of follow-up with an uncemented tapered titanium stem still in clinical use today. METHODS: We reviewed the clinical and radiographic results of 326 THAs performed in 326 patients (for 28 patients with bilateral THA, only the first hip was included in the analysis to ensure independent observations) using an uncemented grit-blasted, tapered collarless titanium alloy (TiAl6Nb7) stem between January 1985 and December 1989. In that same timeframe, we performed 1038 primary THAs. During that time, we used cementless stems in patients without severe femoral canal deformity and adequate bone stock for uncemented femoral fixation as determined by using the indication criteria described by the developer. In all, 34% (354 of 1038) were cementless; all cementless stems implanted during that time were the stem being studied here. No others were used. The mean (range) age at the time of surgery was 56 years (13-81 years). Sixty-seven patients were younger than 50 years at the time of primary THA. A competing risk survivorship analysis was used to estimate long-term survival. The minimum follow-up was 27 years (mean 28 years; range 27-32 years); at that time, 169 patients had died, and four patients were lost to follow-up. RESULTS: Survivorship at 28 years with revision of the femoral component for any reason as the endpoint was 87% (95% CI 83 to 90). Survivorship for femoral revision for aseptic loosening as the endpoint was 94% at 28 years (95% CI 90 to 96). Survival in patients younger than 50 years at the time of primary THA was 89% (95% CI 78 to 95) and 95% (95% CI 86 to 98) at 28 years for the endpoints of all stem revisions and aseptic stem loosening, respectively. The overall cumulative incidence of stem revision for periprosthetic femoral fracture was 4% (95% CI 2 to 7) at 28 years. The overall THA survival rate at 28 years with revision for any reason as the endpoint was 57% (95% CI 51 to 62). CONCLUSIONS: Uncemented femoral fixation of a tapered collarless titanium alloy stem was reliable into the early fourth decade, especially in patients younger than 50 years. Late stem failures in the third and early fourth decade were mainly because of periprosthetic femoral fracture, while aseptic loosening occurred in undersized stems during the early second decade. LEVEL OF EVIDENCE: Level IV, therapeutic study.

How Can Patients With Mobile Hips and Stiff Lumbar Spines Be Identified Prior to Total Hip Arthroplasty? A Prospective, Diagnostic Cohort Study.

BACKGROUND: Patients with reduced lumbar spine mobility are at higher risk of dislocation following total hip arthroplasty (THA). Therefore our study aimed to (1) define the optimal protocol for identifying patients with mobile hips and stiff lumbar spines and (2) determine clinical and standing radiographic parameters predicting these patients. METHODS: A cohort of 113 patients with end-stage hip osteoarthritis awaiting THA was prospectively studied. Clinical data, patient-reported outcome measures, and spinopelvic radiographs were assessed with the patient in the standing, "relaxed-seated," and "deep-flexed seated" position. A "hip user index" was calculated quantifying the percentage of sagittal hip movement compared to overall movement between the standing and deep-flexed seated position. RESULTS: Radiographs in the relaxed-seated position had an accuracy of 56% (95% confidence interval 46-65) to detect patients with stiff lumbar spines, compared to a detected rate of 100% in the deep-flexed seated position. A standing pelvic tilt of ≥19° was the only predictor for being a hip user with a sensitivity of 90% and specificity of 71% (area under the curve 0.83). Patients with a standing pelvic tilt ≥19° and an unbalanced spine with a flatback deformity had a 30× fold relative risk (95% confidence interval 4-226, P < .001) of being a hip user. CONCLUSION: Patients awaiting THA and having combined high hip and reduced lumbar spine mobility can be screened for with lateral standing radiographs of the spinopelvic complex. Hip user verification should be done utilizing radiographs in the deep-flexed seated position due to a higher accuracy compared to relaxed-seated radiographs. LEVEL OF EVIDENCE: Level II, diagnostic study.

Does Functional Cup Orientation Change at Minimum of 10 Years After Primary Total Hip Arthroplasty?

BACKGROUND: Cup orientation has been shown to influence the postoperative risk of impingement and dislocation following total hip arthroplasty (THA) and may change over time due to changes in pelvic tilt that occur with aging. The purpose of this study is to determine if there is a significant change in acetabular cup inclination and anteversion over a 10-year period following THA. METHODS: A retrospective, multisurgeon, single-center cohort study was conducted of 46 patients that underwent THA between 1995 and 2002. A total of 46 patients were included, with a median age at surgery of 56 years, and a median time between initial postoperative radiograph and the most recent one being 13.5 years (minimum 10 years). Cup orientation was measured from postoperative and follow-up supine anterior-posterior pelvic radiographs. Using a validated software, inclination and anteversion were calculated at each interval and the change in cup anteversion and inclination angle was determined. Furthermore, the difference in the sacro-femoral-pubic angle was measured, reflecting the difference in pelvic tilt between intervals. RESULTS: No significant difference was detected between measurements taken from initial postoperative radiograph and measurements a minimum of 10 years later (P > .45), with the median (interquartile range) change in anteversion, inclination, and sacro-femoral-pubic being 0° (-1° to 3°), 1° (-3° to 2°), and 0° (-2° to 3°), respectively. CONCLUSION: Our study found no significant change in functional cup orientation a minimum of 10 years after THA. No shifts in functional cup orientation as a result of altering spinopelvic alignment seemed to be present over a 10-year period.

[Battle: Indication for surgery in hip-spine syndrome-Hip or spine first? : The spine surgeon's view]. / Battle: Operationsindikation beim Hip-Spine-Syndrom ­ Die Hüfte oder die Wirbelsäule zuerst? : Die Sicht des Wirbelsäulenchirurgen.

Pathologies of the hip, spine and the lower extremity are often concomitant due to their three-dimensional anatomic and physiological interrelation. The real challenge lies in defining which of the pathologies is most relevant for the patient in terms of clinical symptoms and which organ should be treated first. The purpose of this review article is two-fold: Firstly, to explain the treatment dilemma of hip-spine syndrome to the treating physician. Secondly, to highlight the significance of spinal pathology in this context.

Pathologic spinopelvic balance in patients with hip osteoarthritis : Preoperative screening and therapeutic implications.

Recently spinopelvic balance and mobility, i.e. the dynamic interaction of the spine, pelvis and the femur in the sagittal plane between different postures, has been identified as a relevant factor influencing the outcome of primary total hip arthroplasty (THA). Individual spinopelvic balance and mobility seem to affect patient reported outcome and the risk of impingement and dislocation following THA. The aim of this article is to provide a concise overview of normal and pathologic spinopelvic alignment, to characterize relevant spinopelvic parameters and the diagnostic assessment in patients with hip OA and to discuss potential implications for THA with respect to implant selection and component orientation.Spinopelvic characteristics are highly variable. Patients with stiff lumbar spines and mobile hips seem to be at an increased risk of impingement and dislocation and can be screened with single lateral standing radiographs of the spinopelvic complex before THA. In patients with hip and spine pathology, particular attention should be paid to evaluate the individual pathoanatomy of the hip and established clinical measurements should be diligently taken with respect to the reconstruction of the center of rotation, hip offset, leg length and soft tissue tension in order to minimize the risk of impingement and dislocation. No evidence-based recommendations for novel target zones concerning implant position can currently be made. In patients at risk 36 mm heads should be used whenever possible. In high risk patients, such as the combination of a stiff unbalanced lumbar spine ("flatback") and a mobile hip or in the presence of long spinal fusions or fusions involving the sacrum, dual mobility cups offer additional stability.

Fifty-six percent of proximal femoral cortical hypertrophies 6 to 10 years after Total hip arthroplasty with a short Cementless curved hip stem - a cause for concern?

BACKGROUND: Thigh pain and cortical hypertrophies (CH) have been reported in the short term for specific short hip stem designs. The purpose of the study was to investigate 1) the differences in clinical outcome, thigh pain and stem survival for patients with and without CHs and 2) to identify patient and surgery-related factors being associated with the development of CHs. METHODS: A consecutive series of 233 patients with 246 hips was included in the present retrospective diagnostic cohort study, who had received a total hip arthroplasty (THA) between December 2007 and 2009 with a cementless, curved, short hip stem (Fitmore, Zimmer, Warsaw, IN, USA). Clinical and radiographic follow-up, including the radiographic parameters for hip geometry reconstruction, were prospectively assessed 1, 3, and 6 to 10 years after surgery. RESULTS: Cortical hypertrophies were observed in 56% of the hips after a mean of 7.7 years, compared to 53% after 3.3 years being mostly located in Gruen zone 3 and 5. There was no significant difference for the Harris Hip Score and UCLA score for patients with and without CHs. Only one patient with a mild CH in Gruen zone 5 and extensive heterotopic ossifications around the neck of the stem reported thigh pain. The Kaplan Meier survival rate after 8.6 years was 99.6% (95%-CI; 97.1-99.9%) for stem revision due to aseptic loosening and no association with CHs could be detected. Postoperative increase in hip offset was the only risk factor being associated with the development of CHs in the regression model (ΔHO; OR 1.1 (1.0-1.2); p = 0.001). CONCLUSIONS: The percentage of cortical hypertrophies remained almost constant in the mid-term compared to the short-term with the present cementless short hip stem design. The high percentage of cortical hypertrophies seems not be a cause for concern with this specific implant in the mid-term. LEVEL OF EVIDENCE: Diagnostic Level IV.