Stem Alignment Research Articles

Biomechanical reconstruction parameters obtained after direct anterior approach total hip arthroplasty do not compromise clinical outcome.

Accurate reconstruction of biomechanical parameters following total hip arthroplasty (THA) is crucial for good joint function. We investigated how reconstruction parameters achieved by minimally invasive anterior (MIS) THA may influence function and patient-related outcomes. A consecutive series of 95 patients treated by MIS THA for primary osteoarthritis were retrospectively reviewed. Primary outcome measures were Harris Hip Score (HHS), hip disability and osteoarthritis outcome score (HOOS) and EQ-5D. Femoral offset (FO), abductor lever arm (ALA), centre of rotation (CoR), leg length discrepancy (LLD), cup version and stem alignment were measured pre- and post-operatively. Obtained reconstruction parameters compared to the contralateral hip were used as independent variables in a multivariate regression with each primary outcome measure as dependent variable. Mean age at surgery was 69years. HHS rated 94.7% of patients as good/excellent and mean EQ-5D was 0.82. Post-operative HOOS subscales showed no statistical difference compared to the Italian benchmark population. Stem alignment averaged 0.2° valgus, mean cup inclination was 37.8° and mean anteversion was 12.8°. When compared to the contralateral side, CoR was post-operatively elevated by 2.6mm and medialized by 2.4mm averagely. An average FO reduction of -0.5mm was observed while FO ratio increased by 1.9% averagely. ALA decreased by -3.3mm while LLD was 2.3mm averagely. Multivariate regression analysis revealed a significant contribution of ALA to HHS only. Biomechanical parameters achieved by MIS THA are satisfactory with negligible impact on functional results and no impact on patient-related outcomes certifying the high quality achieved in THA.

Functional and radiological outcome in primary ceramic-on-ceramic total hip arthroplasty

Background: Traditionally, total hip arthroplasty (THA) was done using cobalt-chrome into a polyethylene socket. However, because of wearing properties of these implants, implant loosening and loss of bone stock, particularly in younger and more active patients, was seen with greater frequency. This led to the development of ceramic implants having better wear characteristics. Material and Methods: Present study was carried out as prospective study, on 30 patients undergoing primary ceramic on ceramic THA with minimum of 6 months of follow up. For clinical evaluation, Harris Hip score and Modified Merle d'Aubigné and Postel score were calculated pre-operatively and post-operatively. For radiological evaluation, post-operative radiographs were checked for alignment of femoral stem, loosening of stem or acetabular component, osteolysis and presence of heterotopic ossification, at predefined regular intervals. Results: The mean Harris hip score, in our study, increased from 35 pre-operatively to 88.4 post-operatively, and mean Modified Merle d'Aubigné and Postel score increased from 9.3 pre-operatively to 16.2 post-operatively, with 90% hips having good to excellent results. This improvement was statistically significant (p< 0.005). On evaluation of alignment of femoral stems, 28 stems were central (93.3%) and 2 stems were in valgus (6.67%), having no significant clinical outcome. Not a single case of focal osteolysis, stem loosening or heterotopic ossification was seen. Conclusion: We found excellent results of primary ceramic on ceramic THA comparable to available literature, with no serious complication found in any patient. The limitations of our study include the lack of a control group undergoing THA with alternate bearing surfaces, and longer follow up.

Long-Term Clinical and Radiological Outcomes of Primary Total Hip Arthroplasty with Modular Femoral Stem in Middle-Aged Asian Patients

BackgroundThere is insufficient information regarding the outcome of primary total hip arthroplasty (THA) with the modular femoral stem in middle-aged patients. This study aimed to assess long-term clinical and radiological outcomes of primary THA using the original or modified modular hip system (S-ROM) in middle-aged Asian patients. MethodsA retrospective review identified 98 primary THAs that used a modular stem and were undertaken between 1997 and 2009 in patients younger than 58 years, for whom at least 5 years of follow-up data were available. Clinical data and radiograph assessments were reviewed to analyze differences between the original and modified modular stem groups. ResultsThe mean patient follow-up duration was 148.3 months, and the follow-up ratio was 89.1%. The Kaplan–Meier analysis revealed that the survival rate of both stems was 98.9% at 10 years and 89.8% at 15 years. Although no statistically significant differences in the survival rate were observed between the stem designs, the original stem group had increased incidence of thigh pain compared with the modified stem group. In total, 12 and 54 hips showed change in stem alignment and osteolysis, respectively. ConclusionThe findings of this study show that the modular stems have a high survival rate, and results suggest positive outcomes among the Asian population over the long term. Although there were very few differences between the stem designs, the results suggest that the modified modular stem could prevent thigh pain and that selection of the implant based on the bone shape is important for THA.

Quality of the femoral cement mantle in total hip arthroplasty using the direct anterior hip approach.

BackgroundLimited literature exists concerning the femoral cement mantle quality that can be achieved through an anterior approach in total hip arthroplasty (THA). We radiologically evaluated the quality and thickness of the femoral cement mantle in patients undergoing THA utilizing the direct anterior approach (DAA).MethodsImmediate postoperative anteroposterior and lateral radiographs of 116 consecutive patients who underwent hybrid or fully cemented THA using the DAA and cemented Quadra-C stem (Medacta, International, SA, Switzerland) were assessed by 2 arthroplasty surgeons blinded to the study. Surgical indications were hip osteoarthritis or subcapital hip fracture. The cement mantle and stem alignment were evaluated using the Barrack classification and Khalily methods, respectively. After calibration of radiographs, the thinnest part of the cement mantle per Gruen zone was recorded. Parameters were compared between obese and nonobese patients.ResultsAgreement between raters was substantial for the cement quality in anteroposterior (k = 0.707, P ≤ .001) and moderate for lateral radiographs (k = 0.574, P ≤ 001). The cement mantle was graded A in 39.25%, B in 53.0%, and C in 7.75% of anteroposterior radiographs and similarly for lateral radiographs (40.1% A, 51.75% B, 9.5% C). 93% of stems had neutral alignment. The mean thinnest cement mantle (P = .237) and incidence of inadequate cement mantle (<2 mm) per zone (P = .431) were comparable between Gruen zones. The cement mantle quality (P = .174) and inadequacy (P > .05) and stem alignment (P = .652) were comparable between obese and nonobese patients.ConclusionsDAA enables correct implantation and effective cementation of straight femoral stems. A high-quality cement mantle can be achieved using DAA even in obese patients.

The direct anterior approach provokes varus stem alignment when using a collarless straight tapered stem.

Inaccurate stem implantation can cause unsatisfactory offset reconstruction and may result in insufficient gluteal muscle function or aseptic loosening. In this study, stem alignment of a collarless straight tapered HA-coated stem was retrospectively analyzed during the learning phase of the direct anterior approach (DAA) for primary total hip arthroplasty (THA). From Jan 2013 to Jun 2015, a total of 93 cementless THA were implanted in patients with unilateral coxarthrosis via the DAA in a two surgeon setting using the Corail® or Trendhip® stem (DePuy Synthes or Aesculap). Varus(+)/Valgus(-) stem alignment was analyzed in postoperative anteroposterior pelvic radiographs. Effects on femoral offset reconstruction and correlation to patient's individual clinical and radiological parameters were evaluated. 55 stems were implanted in varus (59%), 32 in neutral (34%) and 6 in valgus alignment (7%). Mean stem alignment in varus position was + 2.2° (SD ± 1.4°). Varus alignment was associated with male gender and preoperative coxa vara deformity: low CCD, high femoral offset and long thigh neck (p ≤ 0.001). Alignment was not correlated to femoral offset restoration, BMI or leg length difference. Mean cup inclination was 44° (SD ± 4.7°) and 90% matched the coronal Lewinnek safe zone. In the learning curve, the DAA can be associated with a high incidence of varus stem alignment when using a straight tapered stem, especially in men with coxa vara deformity: low CCD, high femoral offset and long thigh neck. An insufficient capsule release makes femur exposure more difficult and might be an additional factor for this finding. We recommend intraoperative X-ray in the learning phase of the DAA to verify correct implant positioning and to adjust offset options.

Implant positioning among the surgical approaches for total hip arthroplasty: a Bayesian network meta-analysis.

Although there is anatomical individuality among patients, some standardized requirements for component orientation for total hip arthroplasty (THA) exist. To date, no study has compared implant positioning using a network meta-analysis (NMA). Hence, the purpose of this study was to perform a NMA comparing implant positioning among the various approaches for THA. This study was conducted according to the PRISMA extension statement for reporting of systematic reviews incorporating network meta-analyses of health care interventions. All randomized (RCT) and non-randomized (nRCT) clinical trials comparing two or more different approaches for THA were considered for inclusion. For the statistical analysis, the STATA Software/ MP, Version 14.1 (Stata Corporation, College Station, Texas, USA) was used. The NMA was performed through a Stata routine for Bayesian hierarchical random-effects model analysis. We enrolled in the present study, a total of 4060 patients, with a mean of 17.84 ± 16.41months follow-up. The patient baseline data were very homogeneous across the groups concerning age (P = 0.91), sex (P = 0.52), and BMI (P = 0.83). Concerning the cup anteversion, the anterolateral approach reported the value closest to the reference value. The test for overall inconsistency, however, was not statistically significant (P = 0.30). Concerning cup inclination, the lateral approach reported the value closest to the reference value. The test for overall inconsistency was statistically significant (P = 0.01). The anterolateral approach for total hip arthroplasty detected the best femoral stem alignment and cup anteversion. Data concerning cup inclination detected no sufficient transitivity to draw consistent conclusions.

Short stem humeral components in reverse shoulder arthroplasty: stem alignment influences the neck-shaft angle.

Shorter humeral reverse total shoulder arthroplasty (RTSA) stems may reduce stress shielding, however, potentially carry the risk of varus/valgus malalignment. This radiographic study's purpose was to measure the incidence of stem malalignment and thus the realized neck-shaft angle (NSA). The hypothesis was that malalignment of the stem is a frequent postoperative radiographic finding. Radiographs of an uncemented curved short stem RTSA with a 145° NSA were reviewed. The study group included 124 cases at a mean age of 74 (range 48-91) years.The humeral stem axis was measured and defined as neutral if the value fell within ± 5° of the longitudinal humeral axis. Angular values > 5° were defined as malaligned in valgus or varus. The filling ratio of the implant within the humeral shaft was measured at the level of the metaphysis (FRmet) and diaphysis (FRdia). The average humeral stem axis angle was 4 ± 3° valgus, corresponding to a true mean NSA of 149 ± 3°. Stem axis was neutral in 73% (n = 90) of implants. Of the 34 malaligned implants, 82% (n = 28) were in valgus (NSA = 153 ± 2°) and 18% (n = 6) in varus (NSA = 139 ± 1°). The average FRmetand FRdia were 0.68 ± 0.11 and 0.72 ± 0.11, respectively. A low positive association was found between stem diameter and filling ratios (r = 0.39; p < 0.001); indicating smaller stem sizes were more likely to be misaligned. Uncemented short stem implants may decrease stress shielding; however, approximately one quarter were implanted > 5° malaligned. The majority of malaligned components (86%) were implanted in valgus, corresponding to an NSA of > 150°. As such, surgeons must be aware that shorter and smaller stems may lead to axial malalignment influencing the true SA. Level IV, retrospective study.

Does Femoral Morphology Predict the Risk of Periprosthetic Fracture After Cementless Total Hip Arthroplasty?

BackgroundPeriprosthetic femur fracture remains a leading mode of early failure following cementless total hip arthroplasty (THA). The purpose of this study is to determine if a specific femoral morphology is associated with an increased risk of acute, periprosthetic fracture after cementless THA. MethodsAn institutional arthroplasty registry was used to identify 32 primary, cementless THAs revised for acute, postoperative periprosthetic fracture (“fracture” cohort) within 3 months of the index procedure. Patients were matched 1:2 to 64 THAs without fracture (“control” cohort) for age, body mass index, gender, and stem design. Preoperative radiographic measurements performed on anteroposterior pelvis and femur radiographs included the neck-shaft angle, endosteal width at 4 locations, and external cortical diameter at 2 locations. These measurements were used to calculate the morphological cortical index, canal flare index, canal calcar ratio, and canal bone ratio. Postoperative measurements included canal fill and stem alignment. Statistical analyses included clustered regressions, Fisher’s exact test, and Student’s t-test. ResultsThe mean endosteal width at 10 cm distal to the lesser trochanter was greater in fracture patients, although not statistically significant (P = .1). However, this resulted in differences in the canal flare index (P = .03), canal calcar ratio (P = .03), and canal bone ratio (P = .03) between the 2 cohorts. These ratios indicate decreased meta-diaphyseal taper in fracture patients. Preoperative femoral neck-shaft angle was more varus in fracture patients (P = .04). ConclusionPatients sustaining an acute, periprosthetic fracture with cementless femoral fixation after THA had thinner distal cortices and a decreased meta-diaphyseal taper.

Comparison of Supine and Lateral Decubitus Positions for Total Hip Arthroplasty with the Direct Lateral Approach in Overweight and Obese Patients.

Background The purpose of our study is to compare the results of supine and lateral decubitus positions for total hip arthroplasty (THA) with the direct lateral (DL) approach in overweight and obese patients. Methods Patients who had a THA with the DL approach using the lateral decubitus position (LD group) (n = 54) or supine position (S group) (n = 54) or supine position (S group) (Results Both groups did not differ from each other by means of age, gender, BMI, and affected side (p = 0.814, p = 0.814, p = 0.814, p = 0.814, p = 0.814, p = 0.814, p = 0.814, p = 0.814, Conclusions The LD and S groups had comparable functional outcomes one year postoperatively. However, the S group was associated with worse intraoperative outcomes than the LD group.

Do short stems influence the cervico-diaphyseal angle and the medullary filling after reverse shoulder arthroplasties?

BackgroundShorter humeral stems were developed to improve bone preservation, vascularity and osteointegration in reverse total shoulder arthroplasty (RSA). While some studies examined the relationship between canal filling and radiographic changes, none evaluated the association between stem alignment and canal fill ratio (CFR). HypothesisThe hypothesis was that stem misalignment after RSA would be associated with lower CFR. Patients and methodsThe authors retrospectively reviewed immediate postoperative radiographs of 157 patients, comprising 56 men (36%), who underwent RSA with a short uncemented stem with neck shaft angle (NSA) default of 145°. The parameters included postoperative NSA and metaphyseal CFR, both measured with excellent inter-observer agreement. Uni- and multivariable linear regressions were performed to determine associations between postoperative NSA and 5 variables (CFR, gender, age, BMI, and surgical approach). ResultsPostoperative NSA was 149°±8°, exceeding 5° of varus in 15 shoulders (9%) and 5° of valgus in 60 shoulders (38%), and CFR was 58%±8%. CFR was lower in shoulders with varus stem alignment (54%±6%) than shoulders with neutral stem alignment (59%±8%, p=0.033). Multivariable regression revealed that postoperative NSA increased with age (beta: 0.20; p=0.008), was higher for shoulders operated with the subscapularis- and deltoid-sparing approach (beta: 3.82; p=0.040) but lower for men (beta: −4.14; p=0.002). ConclusionsStem misalignment exceeded 5° in 47% of the shoulders. Women, older age, and subscapularis- and deltoid-sparing approach are associated with greater risks of valgus stem positioning, while lower CFR seems to be associated with greater risks of varus stem positioning. Level of evidenceIV; case series.

Mid-term migration pattern of a calcar-guided short stem: A five-year EBRA-FCA-study

BackgroundShort-term results of several short-stem designs have indicated early axial migration. Mid- and long-term results for most designs are lacking. The objective of this study was to evaluate the mid-term migration pattern of a calcar-guided short stem five years postoperative. MethodsImplant migration of 191 calcar-guided short stems was assessed by Ein-Bild-Roentgen-Analysis Femoral-Component- Analysis (EBRA-FCA) 5 years after surgery. Migration pattern of the whole group was analyzed and compared to the migration pattern of implants potentially being “at hazard” with a subsidence of more than 1.5 mm at 2 years postoperatively. Influence of preoperative Dorr types (A vs. B vs. C), age (<70 vs. >70 years), gender (female vs. male), weight (<90 kg vs. >90 kg), BMI (<30 vs. >30) and uni-vs. bilateral procedures on mid-term migration pattern was analyzed. Additionally outcome of varus- and valgus stem alignment was assessed. ResultsMean axial subsidence was 1.5 mm (SD 1.48 mm) at final follow-up. Two years after surgery 73 short stems were classified “at hazard”. Of these stems, 69 cases showed secondary stabilisation in the following period, whereas 4 cases presented unstable with more than 1 mm of further subsidence. Stem revision was not required neither in the group of implants with early stabilisation nor the group with pronounced early onset migration. Male gender and heavy-weight patients had a significant higher risk for axial migration, as well as extensive valgus stem alignment, whereas for Dorr type B, compared to A, no statistical difference could be observed. ConclusionsIn most cases, even in the group of stems being “at hazard”, settling could be documented. While different Dorr types did not show a statistically significant impact on axial migration, particularly in male and heavy-weight patients the risk of continuous subsidence is increased. In those 4 cases with further migration, undersizing of the stem could be recognized. At present, clinical consequences are still uncertain.

Does femoral morphology and stem alignment influence outcomes of cementless total hip arthroplasty with proximally coated double-tapered titanium stems?

Stem subsidence and thigh pain can cause significant patient dissatisfaction after cementless THA. The purpose of this study was to examine the effect of proximal-femoral morphology and stem alignment on clinical outcomes using a double-tapered, cementless titanium femoral component. We retrospectively reviewed 281 consecutive, primary THAs from 2012 to 2014 with a mean follow-up of 4 years. Preoperative radiographs were used to assess femoral neck shaft angle (FNS), canal flare index (CFI), Dorr classification, and greater trochanter (GT) overhang. Postoperative radiographs were used to determine stem alignment and 6-week follow-up radiographs were used to determine subsidence. Clinical outcomes included thigh pain, leg-length discrepancy (LLD), patient-reported outcome measures (PROMs) and revision surgeries. 271 stems (96%) did not subside (<4 mm) and 10 (4%) showed evidence of subsidence (>4 mm). Subsidence was significantly associated with subsequent revision surgery (p < 0.01). 278 stems (99%) were in neutral alignment and 3 in varus (1%). Alignment did not significantly influence subsidence, thigh pain, LLD, revisions, or PROMs. Femoral morphology measures (FNS, CFI, Dorr classification, and GT overhang) were not significantly associated with stem alignment, subsidence, LLD, or revisions. CFI was significantly associated with intraoperative calcar fractures (p = 0.02). GT overhang was associated with thigh pain (p = 0.03) and FNS was inversely associated with postoperative HOOS scores. Subsidence and proximal-femoral morphology are potential sources of postoperative morbidity in certain cementless THA patients. In accordance with prior studies, CFI was identified as a potential risk factor for intraoperative calcar fractures. More research into preoperative femoral morphologies, such as GT overhang and FNS, is warranted as these may contribute to unsatisfactory results related to cementless THA.

Radiographic assessment of cup and stem alignment after CPP-THA combined with portable navigation system

Radiographic assessment of cup and stem alignment after CPP-THA combined with portable navigation system

The effects of patient characteristics and stem alignment on distal femoral cortical hypertrophy after cemented polished tapered stem implantation.

The objective of this study was to evaluate the results of over 10years of total hip arthroplasty (THA) practice with ExeterTM stems and the clinical relevance of distal femoral cortical hypertrophy (DFCH). We retrospectively reviewed 127 hips (120 patients) that had undergone THA with ExeterTM stems between 2004 and 2007. Kaplan-Meier survival analyses for the stem of all 127 hips were performed using different endpoints. Of 127 hips, 100 (94 patients) had complete 10-year follow-up data, including the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ) as the patient-reported outcomes, and the clinical relevance of DFCH was analyzed using multivariable logistic regression analysis. The survival of the stem with the endpoint of re-operation for loosening, > 5-mm subsidence, and re-operation for any reason were 100%, 99.1% (95% CI 97.5-100%), and 98.3% (95% CI 96.0-100%), respectively. Of 100 hips followed completely for 10years, DFCH occurred in 20 hips (20%). The satisfaction and pain visual analog scale of JHEQ revealed high satisfaction and less pain in patients with DFCH. By multivariate logistic regression analysis, body weight > 55kg (odds ratio: 2.88, p = 0.035) and varus stem alignment (odds ratio: 6.56, p = 0.003) were found to be predictors for DFCH. The incidence of DFCH with the ExeterTM stem was 20%. A body weight > 55kg and varus stem alignment are predictors for future DFCH. DFCH with the ExeterTM stem indicates a good outcome with less hip pain.

Mid-term results of a new-generation calcar-guided short stem in THA: clinical and radiological 5-year follow-up of 216 cases

BackgroundIn recent years, a variety of short stems have been introduced. To date, mid- and long-term results of calcar-guided short-stem designs have been rarely available.Materials and methodsTwo hundred and sixteen calcar-guided short stems were included in combination with a cementless cup in a prospective study. Patients were allowed full weight-bearing on the first day postoperatively. Harris hip score (HHS) as well as pain and satisfaction on visual analogue scale (VAS) were assessed during a median follow-up of 61.7 months. Standardised radiographs were analysed at predefined time points regarding radiological alterations such as bone resorption and remodelling, radiolucency, osteolysis and cortical hypertrophy using modified Gruen zones.ResultsAt mid-term follow-up, no revision surgery of the stem had to be performed in the whole collective. At 5 years, HHS was 97.8 (SD 4.7), satisfaction on VAS was 9.7 (SD 0.7), rest pain on VAS was 0.1 (SD 0.5), and load pain on VAS was 0.6 (SD 1.2). Compared to the 2-year results, femoral bone resorption increased significantly at the 5-year follow-up (3.9% versus 42.3%). Rate of femoral cortical hypertrophy remained stable, occurring in a total of 9 hips (4.5%). At the 5-year follow-up, 2 stems (1.0%) showed non-progressive radiolucent lines with a maximum width of 2 mm. Signs of osteolysis were not observed. Compared to the 2-year follow-up, no further subsidence was observed.ConclusionsThe rate of stem revision (0%) at the mid-term follow-up was remarkable and indicates the principle of using a calcar-guided short stem as being a safe procedure. However, signs of bone-remodelling, indicating some amount of stress-shielding, must be acknowledged at 5 years depending on stem alignment and type of anchorage.Level of evidenceIV, Prospective observational studyTrial registration German Clinical Trials Register, DRKS00012634, 07/07/2017 (retrospectively registered)

Effect of Biomechanical and Anatomic Characteristics on Patient-Reported Outcomes Following Total Hip Arthroplasty

Background and Hypothesis: The success of total hip arthroplasty (THA) is often reported in terms of infection and dislocation rates. While studies have examined the effect of acetabular cup position, anteroposterior (AP) femoral stem alignment, changes in leg length and femoral stem offset on dislocation rates, few studies have investigated the effect of these biomechanical parameters on patient-reported outcome measures (PROMS). The purpose of this study was to evaluate how PROMS may differ by THA component placement in a consecutive series of primary THAs. Awareness of the importance of implant positioning may lead to improved surgical technique and optimized PROMS.&#x0D; Experimental Design or Project Methods: 933 consecutive posterolateral approach primary THAs performed between 2011 and 2018 by one surgeon were retrospectively reviewed. Acetabular cup abduction, femoral stem alignment, changes in leg length and total femoral offset were measured on APview radiographs. Prospectively collected Hip Disability and Osteoarthritis Outcome Score/HOOS Jr., University of California Los Angeles/UCLA Activity Level, and satisfaction (5-point Likert scale) were evaluated at minimum one-year.&#x0D; Results: 743 THAs were analyzed. Mean age and BMI were 64 years and 31 kg/m2, respectively. After multivariate analysis, females with neutral to valgus stem placement (p=0.020) and patients with neutral to valgus stem placement regardless of lumbar pain (p=0.034) were more satisfied. In addition, patients with lumbar pain (p&lt;0.001) and patients with high BMI in combination with increased change in femoral offset (p=0.056) had lower overall HOOS Jr. scores. Interestingly, change in leg length was not a significant predictor of any PROMS (power [1-β]≥88.4%).&#x0D; Conclusion and Potential Impact: AP stem alignment may play a role in increased activity level and satisfaction. In addition, high BMI in combination with increased change in femoral offset negatively influenced HOOS Jr. scores. Unsurprisingly, the presence of lumbar pain continues to negatively affect PROMS. Further research is warranted on the influence of THA component placement, spinopelvic parameters, and PROMS.

Occult periprosthetic femoral fractures occur frequently during a long, trapezoidal, double-tapered cementless femoral stem fixation in primary THA

The present study aimed to investigate the prevalence and clinical consequences of occult intra-operative periprosthetic femoral fractures in total hip arthroplasty (THA). Between 2012 and 2017, a total of 113 primary THAs were enrolled. The mean age of the patients was 66.4 ± 7.6 years. We assessed occult intra-operative periprosthetic femoral fractures with the use of computed tomography (CT) and risk factors, including age, sex, body mass index, diagnosis, stem size, and radiographic parameters of proximal femoral geometry were analyzed. We also assessed the differences in thigh pain and stem subsidence and alignment between the patients with and without occult periprosthetic femoral fracture. Occult intra-operative periprosthetic femoral fractures were found in 13 of 113 hips (11.5%). In 9/13 (69.2%) of occult fractures, fracture lines were started from the region below the tip of the lesser trochanter. Six periprosthetic femoral fractures (5.3%) were found during the operation. Out of the five hips that had detected femoral fractures around the lesser trochanter intra-operatively, four hips (80%) showed concurrent occult fractures on different levels. The female sex (P = .01) and canal filling ratio at 7 cm below the tip of the lesser trochanter (P = .01) were significantly different between the patients with and without occult periprosthetic femoral fracture. The sex was significantly associated with an increased risk in predicting an occult intra-operative periprosthetic femoral fracture (odds ratio of male, 0.25 compared with the female; 95% CI, 0.08–0.85; p = .02). There was a significant difference in the incidence of thigh pain between occult fracture group and non-occult fracture group (P < .05). There were no significant differences in stem subsidence and alignment between the patients with and without occult periprosthetic femoral fracture. All 13 cases of occult intra-operative periprosthetic femoral fractures were healed at the final follow-up. Occult periprosthetic femoral fractures are common during a long, trapezoidal, double-tapered cementless femoral stem fixation in primary THA, that CT scans are helpful to identify them, and that these fractures do not adversely affect the implant’s survival if a rigid fixation of the implants has been achieved.

Correlation between anterior thigh pain and morphometric mismatch of femoral stem.

BackgroundPostoperative pain occurring after hip arthroplasty has become common since the expanded use of cementless femoral stems. The characteristic pain develop in the anterolateral thigh area. This study aimed to predict anterior thigh pain based on the measurements of postoperative anteroposterior (AP) and lateral (Lat) radiographs of the hip joint. MethodsThe present study included 26 patients (29 hips) who underwent total hip replacement or bipolar hemiarthroplasty between March 2010 and May 2016, whose complete clinical information was available. AP and Lat radiographs of the affected hip were taken on the day of surgery and 1 and 6 months postoperatively. Patients with improper radiographs were excluded. The distance from the femoral stem to the nearest cortical bone in the distal region of the stem was measured. The patient group with a visual analog scale (VAS) score of ≥6 points was designated as patients with anterior thigh pain.ResultsSex, age, weight, height, body mass index, and bone mineral density in the lumbar spine and femur did not have a significant effect on postoperative VAS scores (p>0.05). Presence of contact between the femoral stem and cortical bone was associated with postoperative anterior thigh pain. ConclusionHip AP and Lat radiographs are usually taken to confirm fixation and alignment of the femoral stem after hip arthroplasty. The measurement method introduced in this study can be utilized for predicting anterior thigh pain after hip arthroplasty.

A shortened uncemented stem offers comparable positioning and increased metaphyseal fill compared to a standard uncemented stem

BackgroundShortened stems are increasingly used in uncemented total hip arthroplasty (THA) as they represent a compromise between the metaphyseal anchorage of short stems and the facilitated axial alignment of standard stems. The purpose of this study was to compare the metaphyseal canal-fill ratio (CFR) and axial alignment of a shortened double-tapered stem with those of a standard stem. The hypothesis was that the shortened stem would achieve greater metaphyseal fill and comparable axial alignment.MethodsThe authors reviewed routine follow-up anteroposterior radiographs taken 2 months after THA to evaluate metaphyseal fill and axial alignment of a shortened stem (n = 96) and a standard stem (n = 101). The CFR was calculated at the level of the tip and superior margin of the lesser trochanter. Stem alignment was defined as the angle between the stem axis and the proximal anatomic femoral axis. Stems were classified as being in varus or valgus alignment if they deviated by more than 3° from the anatomic axis of the femur.ResultsHips implanted with shortened and standard stems had comparable demographics and axial alignment (1.1° ± 1.7° vs 0.8° ± 1.2°; p = 0.331). However, varus alignment was observed in 5% of shortened stems compared to only 1% of standard stems, though this difference was not significant (p = 0.111). The femoral CFR was greater using shortened stems than using standard stems, both at the level of the tip of the lesser trochanter (0.91 ± 0.05 vs 0.85 ± 0.08; p < 0.001) and at its superior margin (0.76 ± 0.06 vs 0.72 ± 0.07; p < 0.001).ConclusionsCompared to the standard stem, the shortened stem had increased metaphyseal filling and equivalent alignment. These findings suggest that shortened stems could provide adequate metaphyseal fixation and correct alignment. Further studies remain necessary to evaluate how shortened stems perform in terms of osseointegration, clinical outcomes and survival.

The \u2018critical trochanter angle\u2019: a predictor for stem alignment in total hip arthroplasty

IntroductionStem malalignment can affect offset reconstruction and may result in gluteal muscle insufficiency. In this retrospective study, a novel geometric angle named ‘critical trochanter angle’ (CTA) is described and investigated towards the risk of malposition of a collarless straight tapered hydroxyapatite-coated stem in primary total hip arthroplasty (THA).Material and methodsA total of 100 cementless THA were implanted in patients with unilateral coxarthrosis via the direct anterior (n = 50) or direct lateral Hardinge approach (n = 50) in a two surgeon setting using the Corail® or Trendhip® stem (DePuy Synthes or Aesculap). Stem alignment was analysed in postoperative AP pelvic radiographs and correlated to the CTA: the angle crest was defined by the intersection of the femoral shaft and neck axis and the angle was measured between the shaft axis and a leg intersecting the vertex between the lateral and superoposterior facet of the trochanter.ResultsForty-seven stems were implanted in varus (≥ + 1°), 42 in neutral (< + 1°/> − 1°) and 11 in valgus position (≤ − 1°). The mean critical trochanter angle was 25.0° (SD ± 7.5°), and there was a negative and statistically significant correlation to stem alignment (r = − 0.52; p ≤ 0.001) independent from the surgical approach. For stem malposition of 2° and above (n = 23), mean CTA was 17.2° for varus (n = 20) and 31.6° for valgus (n = 3). A CTA lesser or equal to 22.75° had a sensitivity of 90% and specificity of 80% for varus stem position of 2° or greater. Specificity raised to 100% with a cutoff CTA of 12.5° or lesser.ConclusionVarus stem alignment in THA is associated with coxa vara deformity and a radiological low CTA. In preoperative planning, the critical trochanter angle can help to evaluate the risk for intraoperative stem malpositioning. If navigation or robotic assistance is not available when using this stem design, we recommend an intraoperative x-ray to verify correct implant positioning in patients with a CTA under 20° or above 30°.