High varus stem alignment in short-stem total hip arthroplasty: a risk for reconstruction of femoro-acetabular offset, leg length discrepancy and stem undersizing?

Comparison of mid-term clinical and radiological results of short and conventional femoral stems in total hip arthroplasty

This study aims to answer the question: Which are superior-conventional or short femoral stems?. An Optymis stem was used as a short-femoral stem, and an Accolade II stem was used as a conventional-femoral stem. There were 95 patients in the short femoral stem group (Group 1) and 90 in the conventional stem group (Group 2). The SF-36 Life Quality Score, thigh pain, and the Harris Hip Score were used to evaluate the patients' clinical outcomes. Pre-operative, immediate post-operative, and final follow-up x-rays were used for radiological evaluation. Stem varus/valgus alignment, hip offset changing, acetabular anteversion/inclination changing, femoral migration, acetabular migration, periarticular ossification, and osteointegration evaluation were assessed for both groups. The mean follow-up time was 5.5 years for Group 1 and 5.2 years for Group 2. No significant difference existed between the two groups in terms of clinical scores (Harris Hip Score, SF-36). Thigh pain was significantly higher in Group 2 (p = 0.0001). As for radiological parameters, Group 1 exhibited more varus position-related results. In terms of angular stability, Group 1 was found to be more unstable than Group 2 (p = 0.0001). The power to reconstruct femoral offset was superior in Group 1. Periarticular ossification was more frequent in Group 2. Femoral osteointegration was denser proximally in Group 1 and distally in Group 2. When mid-term radiological and clinical results of both femoral stems are evaluated, they have no superiority over each other.

Native hip geometry restoration in total hip arthroplasty: a retrospective analysis of eight different short stems

PURPOSE

To compare different types of short stems (SS) in terms of native hip geometry reproducibility, analyzing centrum-collum-diaphyseal angle (CCD) and femoral offset (FO). These parameters allow the SS to be adapted to patient's anatomy in order to ensure better functional outcomes in total hip arthroplasty (THA).

METHODS

A total of 387 cases of SS met the inclusion criteria. CCD and FO were measured using MediCAD® software Version 6 in preoperative (preop-) and postoperative (postop-) X-rays at 6-12 months after surgery. Considering preop-CCD, the sample was divided into three groups: ≤ 124.9° (A); 125°-129.9° (B); and ≥ 130°(C). Preop- and postop-CCD and FO and the respective average difference (Δ) were examined considering the SS individually and within groups, to verify reproducibility of these parameters.

RESULTS

The SS considered were eight: Fitmore Zimmer, Pulchra Adler, TRIS Adler, Trifit Corin, Trilock Depuy, Actis Depuy, Profemur Microport, and SMF Smith&Nephew. Groups A, B, and C consisted, respectively, of 113, 124, and 150 cases. Considering all cases, there was a statistically significant (p < 0.05) increase in CCD and FO with surgery. Overall, Trifit and Trilock stems were the best in reproducing preop-CCD, Trifit itself followed by Pulchra and Profemur for preop-FO. In groups A and C, the reproduction of preop-CCD was better than preop-FO, in contrast in group B. With regard to preop-CCD reproduction, in group A Trifit and Pulchra, in group B Fitmore and Trifit, and in group C Fitmore and Pulchra were the best. Fitmore in group A, SMF in group B, Pulchra and Trilock in group C were the worst in reproducing preop-FO.

CONCLUSION

Each hip anatomy is unique, and reproduction of preop-CCD and preop-FO can be achieved with different SS characteristics. Accurate knowledge of the stems and performing correct preop- planning are crucial to allow the best restoration of the patient's native hip geometry in THA.

Do all short stem types restore biomechanical parameters of the hip? Comparison according to femoral neck osteotomy levels

PURPOSE

There is no consensus on ideal short femoral stem design. A classification system proposed by Feyen and Shimmin divides short stems in two types according to femoral neck osteotomy levels: subcapital (IIIA) and standard (IIIB). The study aims to determine which design type is more successful in restoring native biomechanical parameters and whether stem type has an impact on clinical results.

METHODS

In this retrospective comparative study, patients that have undergone short stem hip arthroplasty were evaluated according to stem types: type IIIA (n = 52, 66.7%) (Mathys Optimys) and IIIB (n = 26, 33.3%) (Implantcast Aida and Smith & Nephew SMF). Pelvis X-rays were assessed in terms of femoral neck length, horizontal and vertical hip centres of rotation, horizontal and vertical femoral offsets, abductor lever arm lengths, leg lengths, and stem-shaft angles. Improvement in Harris hip scores, differences between post-operative and pre-operative measurements, and stem-shaft angles were evaluated and compared between two groups.

RESULTS

Mean femoral neck resection (8.27 ± 6.68 mm in IIIA and 15 ± 6.33 mm in IIIB) was significantly different between both groups (p < 0.001). Harris hip scores were increased at post-operative six months in both groups with no difference (84.4 ± 6.4 and 84.6 ± 5.5, p = 0.4). The absolute values of differences between pre-operative and post-operative horizontal centres of rotation (p = 0.63), vertical centers of rotation (p = 0.75), horizontal femoral offsets (p = 0.78), vertical femoral offsets (p = 0.83), abductor lever arm distances (p = 0.63), and leg length (p = 0.21) measurements were not different between both groups. Stem positions were both varus with no statistically significant difference between groups (p = 0.14).

CONCLUSION

We found no difference regarding restoration of biomechanical parameters between short stem designs with different levels of neck osteotomy. Additionally, short stem can mostly result in varus component positioning regardless of the level of neck osteotomy.

Comparison of conjoined tendon-preserving posterior approach and conventional posterolateral approach in hemiarthroplasty for femoral neck fracture in the elderly: A multicenter (TRON group) retrospective study

BACKGROUND

Femoral neck fractures (FNF) are one of the most common traumatic injuries in the elderly. The conjoined tendon-preserving posterior (CPP) approach was developed as a modification of the conventional posterolateral (PL) approach in hemiarthroplasty (HA) for displaced femoral neck fractures (FNF) to reduce postoperative dislocation. We hypothesized that the CPP approach would result in fewer dislocations and similar functional and radiographic outcomes compared to the PL approach.

PATIENTS AND METHODS

This was a retrospective multicenter (TRON group) study. We evaluated the rate of complications, and functional and radiographic outcomes for patients aged >65 years who underwent HA via the PL approach or the CPP approach from 2017 to 2019 and followed up for at least 24 months. To adjust for baseline differences between the groups, a propensity score-matching algorithm was used in a 1:1 ratio.

RESULTS

We identified 135 patients who underwent HA via the PL approach and 135 patients via the CPP approach. The mean follow-up period was 32.4 ± 14.0 months. The incidence of dislocation was 6 in 135 patients (4.4%) in the PL group and 0 in 135 patients (0%) in the CPP group, and there was significant difference (p = 0.04). Operation time was equivalent between the two groups (73.1 ± 30.4 vs. 71.8 ± 30.0 min; p = 0.72). The rate of varus insertion of stems in the PL group lower than that in the CPP group (19.3% vs. 33.3%; p = 0.01). Postoperative Parker's mobility score was similar between the two groups at 12 months follow-up (6.17 vs. 6.27; p = 0.81).

CONCLUSION

The CPP approach showed a significantly lower dislocation rate, similar functional outcome and more varus stem insertions compared with the PL approach in this retrospective study.

Mean 23-Year Outcomes of Total Hip Arthroplasty Using a Modular Femoral Stem With Metaphyseal Fixation Sleeve

BACKGROUND

Although the modular sleeve concept for femoral implants has several advantages, studies reporting on greater than 20-year outcomes are limited. This study aimed to report the mean 23-year results of total hip arthroplasty (THA) using a modular stem with metaphyseal fixation sleeve.

METHODS

This study reviewed primary THAs performed using a modular stem between October 1994 and April 1998. Of the 272 hips (221 patients) identified, 220 hips (177 patients) satisfying the minimum 20-year follow-up were included. The Harris Hip Score was used for clinical evaluation. Final hip radiographs were analyzed to evaluate the implant stability and the extent of femoral osteolysis. The mean follow-up duration was 23 years (range, 20 to 28).

RESULTS

The mean Harris Hip Score improved from 38 points (range, 26 to 67) preoperatively to 90 points (range, 71 to 100) at the final follow-up (P < .001). Femoral osteolysis was observed in 146 hips (67.1%), but 145 were located proximal to the osseo-integrated sleeve. Overall, 4 femoral revisions were performed; 2 for chronic infection, one for aseptic loosening, and one for periprosthetic femoral fracture. Of the 19 (8.6%) periprosthetic femoral fractures, the most common type was Vancouver AG (13 hips). One (0.5%) asymptomatic distal stem fracture occurred, while no complications were identified at the stem-sleeve junction. Implant survivorship free of any femoral revision was 98.3% at 23 years.

CONCLUSIONS

A THA using a modular stem with metaphyseal fixation sleeve demonstrated 98.3% stem survivorship with excellent clinical outcomes at a mean follow-up of 23 years in non-obese patients.

Improved radiographic outcomes and decreased complications rate on the femoral side can be achieved by a novel designed whole-process robotic assisted hip system for total hip arthroplasty: a prospective randomized controlled trial

Postoperative complications due to inaccurate prosthesis positioning are the main causes of early revision. The aim of this study was to (1) determine whether novel designed whole-process robotic assisted hip system allowed better radiographic outcomes and lower complications risk on the femoral side particularly stem subsidence compared to conventional THA, and to (2) identify the comparison of early clinical outcomes. 72 patients were initially enrolled and randomly divided into 2 groups. Finally, only 65 patients (31 RA-THAs, 34 C-THAs) were analyzed who had full 18-month follow-up data. Radiographic follow-up was performed at immediate and 6-month postoperatively, while clinical follow-up at 18-month postoperatively. Stem-related radiographic outcomes, femoral side complications and clinical scores were compared. The robotic arm allowed better radiographic outcomes of the femoral side, including a higher canal fill ratio (CFR) at B1 (P = 0.040), more neutral stem alignment (P = 0.029), lower subsidence (P = 0.023) and lower leg length discrepancy (LLD) (P = 0.010). In addition, low CFR at B1 (P = 0.001) was found the risk factor for subsidence. However, early clinical outcomes were consistent between both groups. The novel designed whole-process robotic assisted hip system covers both femoral and acetabular side operations. It allows accurate and safe manipulation of femoral side, including better stem-related radiographic outcomes and lower risk of subsidence and LLD. However, no advantage of robotic system in early clinical score was identified. Clinical trial registration number: ChiCTR2100044124.

Effect of short stem alignment on initial fixation, stress transfer, and failure risk

BACKGROUND

Short stems are advantageous for revision as they preserve autogenous bone. At present, the method of short-stem installation is determined based on the surgeon's experience.

OBJECTIVE

To provide the guideline for installing a short stem, we aimed to investigate the alignment effect on the initial fixation of the stem, stress transfer, and the risk of failure numerically.

METHODS

Models in which the caput-collum-diaphyseal (CCD) angle and flexion angle were hypothetically changed based on the two clinical cases of hip osteoarthritis were analyzed using the non-linear finite element method.

RESULTS

The medial settlement of the stem increased in the varus model and decreased in the valgus model. With varus alignment, the stresses acting on the femur were high in the distal to the femoral neck. In contrast, the stresses in the proximal to the femoral neck tend to be higher with valgus alignment, although the difference in the femur stress between varus and valgus alignment was slight.

CONCLUSION

Both initial fixation and stress transmission are lower when the device was placed in the valgus model than in the actual surgical case. In order to obtain initial fixation and suppress stress shielding, it is essential to extend the contact area between the medial portion of the stem and the femur along the bone axis, and to ensure adequate contact between the lateral portion of the stem tip and the femur.

Retrospective clinical and X-ray-based outcome analysis of a short-stem hip arthroplasty taking into account the operative learning curve over 7 years in the 3-year control course

INTRODUCTION

Self-monitoring is crucial to work progressively with a high-quality standard. A retrospective analysis is a valuable tool for studying the postoperative outcome of a prosthesis and for evaluating the learning process for the surgeon.

MATERIALS AND METHODS

The learning process of one surgeon was analysed in 133 cases of hip arthroplasty. These were divided into seven groups representing the surgical years 2008-2014. Over the course of 3 postoperative years, a total of 655 radiographs were analysed at regarding three radiological quality parameters (centrum-collum-diaphyseal angle (CCD angle), intramedullary fit&fill ratio (FFR), and migration) and ancillary outcome parameters (Harris Hip Score (HHS), blood loss, operating time, and complications). This period was divided into five times: 1st-day post-op, 6 M, 12 M, 24 M, and 36 M. Bivariate Spearman's correlation analysis and pairwise comparisons were performed.

RESULTS

The total collective achieved a proximal FFR of over 0.8. The distal prosthesis tip migrated and was located on the lateral cortex within the first months. The CCD angle initially showed a variation with a subsequent constant course. The HHS showed a significant increase (p < 0.001) to over 90 points postoperatively. Over time, the operating time and blood loss decreased. Intraoperative complications existed only at the beginning of the learning phase. A learning curve effect can be determined for almost all parameters by comparing the subject groups.

CONCLUSIONS

Operative expertise was shown to gain through a learning curve, whereby postoperative results corresponded to the system philosophy of the short hip stem prosthesis. The distal FFR and the distal lateral distance could represent the principle of the prosthesis, which overall could be an interesting approach for verification of a new parameter.

Progressive lateralization and constant hip geometry in children with DDH, NDH, and LCPD following hip reconstructive surgery: a cohort study of 73 patients with a mean follow-up of 4.9 years

BACKGROUND

Pelvic and femoral osteotomies have been effective methods to treat developmental dysplasia of the hip (DDH), neurogenic dislocation of the hip (NDH), and Legg-Calvé-Perthes disease (LCPD). The aim of this study was to evaluate the mid-term results after hip reconstruction in children with DDH, NDH, and LCPD.

METHODS

In a retrospective study, X-rays of 73 children (2-19 years) with DDH, NDH, and LCPD were measured before, 3 months, and at final follow-up (FU) after hip reconstructive surgery (open reduction, and femoral and/or pelvic osteotomy ± soft-tissue procedures between 2008 and 2018). Measurement of hip geometry included acetabular index (AI), center-edge angle (CE), and Reimers migration index (RMI). Mean follow-up time at final FU was 4.9 years. P value was set P < 0.05.

RESULTS

After surgery (femoral osteotomy: 84 hips, Salter innominate osteotomy: 21 hips, Pemberton osteotomy: 30 hips, open reduction: 28 hips, Chiari osteotomy: 4 hips, and soft-tissue release: 24 hips), hip geometry parameters improved significantly. Nevertheless, at final FU, there was deterioration in hip geometry with femoral head lateralization (RMI) compared to the data at 3 months after surgery (RMI: preop/3 months/final FU: 40.6 ± 16.1%/6.1 ± 9.0/15.4 ± 16.0%; CE: 11.3° ± 20.0°/30.2° ± 9.5°/27.9 ± 15.4°; AI: 28.8° ± 9.6°/19.1° ± 7.6°/18.3 ± 7.6°). Sub-group analysis did not show differences concerning the progression of RMI in DDH, NDH, and LCPD at final FU. Regardless of basic disease, the lateralization was observed in all three groups (DDH, NDH, and LCPD) and statistically significant comparing X-rays 3 months postoperatively to maximum follow-up (DDH; NDH; LCPD: 2.7 ± 6.8%/7.6 ± 10.1%; 13.7 ± 15.3%/22.8 ± 19.8%; 1.7 ± 4.1%/14.9 ± 11.3%). Additional soft-tissue release techniques in patients with DDH or NDH did not show postoperative differences with statistical significance. Concerning surgical techniques, a connection between the lower RMI and the procedure of osteotomy of the ilium was found. In 25 patients, (34%) complications were observed: superficial skin lesions in 8, deep skin lesions in 3, contraction of adductors in 3, subluxation in 2, dislocations of the cast in 2, osteonecrosis of the femoral head in 2 cases, reluxation in 1, infection of the implanted plate in 1, compliance problem in 1, delayed bone healing in 1, and contraction of knee flexors in 1 case.

DISCUSSION

The basic results of this study show a significant improvement of hip geometry at a follow-up of 4.9 years and prove findings of previously published literature. Moreover, the study was able to show a progression of RMI in all patient groups, which have undergone reconstructive surgery, despite basic hip geometry data (AI, CE angle) did not change. Those findings were independent from underlying pathology. Complications were counted in 34% of the patients and involved all known adverse events after hip reconstructive surgery. This makes clear why annual follow-up checks are needed not to miss the right indication for revision surgery.

CLINICAL RELEVANCE

Evidence level: Level IV, case series.

TRIAL REGISTRATION

This manuscript is part of a prospective randomized clinical trial, registered in the German Clinical Trials Register DRKS-ID: DRKS00016861.

The 'critical trochanter angle' does not show superiority over the CCD angle in predicting varus stem alignment in cementless short-stem total hip arthroplasty

PURPOSE

Varus positioning of the femoral stem can affect the hip offset (HO). The critical trochanter angle (CTA) was introduced in 2019 as a novel geometric angle, to predict varus stem alignment in cementless straight stem THA. The aim of this study was to evaluate the applicability of the CTA as a predictor for stem alignment in THA with a cementless neck resecting short stem.

PATIENTS AND METHODS

In this retrospective study, 106 patients (index surgery 2014-2019) with unilateral THA and a morphologically healthy contralateral hip as a reference (Kellgren-Lawrence ≤ 1) were included. A cementless short stem with meta-diaphyseal fixation and press-fit cup was implanted in all cases. Stem alignment, CCD angle, CTA and offset reconstruction were measured on preoperative and 3 months postoperative AP radiographs of the pelvis.

RESULTS

Preoperative lower CTA and lower CCD angle were positively correlated (r = 0.472; p < 0.001). Higher varus stem alignment is correlated with lower CTA (r = - 0.384; p < 0.001) and lower CCD angle (r = - 0.474; p < 0.001). A CTA of 23.1° or lower showed a sensitivity of 59.1% and a specificity of 87.1% (AUC: 0.733) and a CCD angle of 132.75° or lower a sensitivity of 68.2% and a specificity of 80.6% (AUC: 0.77) for a varus stem alignment > 3°.

CONCLUSION

The CTA is also applicable in cementless THA with a neck resecting short stem to evaluate risk of intraoperative varus stem positioning. The CCD angle shows higher sensitivity with marginally lower specificity. Therefore, the CTA is not superior in predicting varus stem alignment in short-stem THA.

LEVEL OF EVIDENCE

IV.

Outcomes of total hip arthroplasty after failed free vascularized fibular grafting for osteonecrosis of the femoral head

PURPOSE

Total hip arthroplasty (THA) after vascularized fibular grafting (VFG) is technically demanding with poorer outcomes compared to primary THA in patients with osteonecrosis of the femoral head (ONFH). The purpose of this study was to compare the outcomes of THA after VFG after removal of the graft with that of primary THA.

METHODS

ONFH patients treated by VFG at a single institution were studied retrospectively. THAs after VFG performed by single arthroplasty surgeon with a single type of THA prosthesis were enrolled in the study. A control cohort of patients was created by 1:1 matching with the THA after VFG cohort according to age, gender, and American Society of Anesthesiology (ASA) score from ONFH patients treated by primary THA. Early and long-term outcomes were compared between the two groups.

RESULTS

A total of 24 hips were included in the THA after VFG group and compared with 24 primary THA hips. No significant difference was noted in stem position. The THA after VFG group had increased blood loss and longer duration of operation time. There were two cases of intraoperative femur fractures in the THA after VFG group. The femoral stem of both groups were stable, with no cases of revision, and similar HHS scores at the last follow-up.

CONCLUSION

THA after VFG may have similar short to midterm outcomes with primary THA after removal of the residual abutting bone graft and correct positioning of the femoral stem.

Varus malalignment of short femoral stem not associated with post-hip arthroplasty fracture

INTRODUCTION

Periprosthetic femoral fractures are an increasingly common post-operative complication of total hip arthroplasty (THA). Though varus malalignment is known to increase fracture risk in standard-length femoral stems, varus malalignment is not as well studied in short stems. Therefore, the purpose of this study was to determine if varus malalignment contributes to early periprosthetic fracture risk in a cementless taper-wedged, short femoral stem.

MATERIALS AND METHODS

This retrospective review included 366 consecutive patients (441 THAs) having undergone THA via anterior approach by a single surgeon between July 2014 and December 2016. All patients received the same short, cementless femoral stem. Femoral component angle was measured on 6-week post-THA weight-bearing radiographs, with malalignment defined as a femoral component angle exceeding 0° ± 3°. Periprosthetic femoral fracture and aseptic loosening occurring within 2 years post-THA were recorded.

RESULTS

The final data analysis included 426 hips with a mean follow-up time of 32.9 ± 10.2 months. Varus and neutral alignment occurred in 84 (19.6%) and 342 (79.9%) of stems, respectively. Three (0.7%) periprosthetic femoral fractures occurred within 2 years, all occurring in patients with neutrally aligned femoral stems. One (0.2%) stem failed due to aseptic loosening and was malaligned.

CONCLUSION

Despite nearly 20% of stems placed in varus alignment, three of the four early complications occurred in a neutrally aligned stem. Based on these results, forceful intraoperative realignment of a short femoral stem with good initial fixation may present an unnecessary increased risk of intraoperative fracture.

Minimally invasive anterolateral approach versus direct anterior approach total hip arthroplasty in the supine position: a prospective study based on early postoperative outcomes

BACKGROUND

Minimally anterolateral approach (MAA) and direct anterior approach (DAA) have been reported as beneficial for total hip arthroplasty (THA) due to their ability to reduce postoperative pain and lead to quicker rehabilitation by preserving muscle insertions. As there is an ongoing debate on the effect of these two approaches on early postoperative outcomes, this prospective study aimed to assess the difference in early clinical, radiological, and patient-reported outcomes between the two minimally invasive approaches.

METHODS

A total of 98 patients, 50 in the MAA group and 48 in the DAA group, were included in the study. Patients with complete data were evaluated preoperatively and postoperatively at 2, 6, and 12 weeks. Clinical measurements, including the ability to climb stairs and walk, 6-min walk test (6MWT), the Forgotten Joint Scale (FJS-12), Japanese Orthopedic Association (JOA) Hip scores, radiological evaluation, and complications were analyzed.

RESULTS

There were no significant differences in clinical outcomes and implant alignments between MAA and DAA groups. In regards to patient-reported outcomes, the FJS-12 was significantly higher in the MAA group compared to group DAA at 2 and 6 weeks postoperatively. However, there was no significant difference in the FJS-12 between the two groups 12 weeks after surgery. The differences also included shorter operative times (62.4 ± 9.05 min vs. 71 ± 8.01 min), less blood loss (132.6 ± 43.31 ml vs. 159.23 ± 37.25 ml), lower Hb drop (29.56 ± 8.02 g/L vs. 36.4 ± 7.12 g/L), and fewer blood transfusions in the MAA group (4.0% vs. 18.8%). The incidence of the lateral femoral cutaneous nerve (LFCN) neuropraxia after surgery was 7 (14.6%) in the DAA group and 0 in the MAA group. One fracture was found in each group and managed conservatively.

CONCLUSION

MAA and DAA approach yielded excellent and similar early clinical outcomes. However, better patient-reported outcomes could be achieved by MAA THA. The MAA resulted in a safer approach associated with shorter operative times, less blood loss, lower Hb drop, fewer blood transfusions, and LFCN neuropraxia than DAA. A longer follow-up is needed to further examine differences between these procedures.