Direct superior approach with standard instrumentation for total hip arthroplasty: safety and efficacy in a prospective 200-case series

Incidence of heterotopic ossification following total hip arthroplasty by approach: a systematic review

BACKGROUND

Heterotopic ossification (HO) formation has been increasingly recognized as a complication of major orthopedic surgeries, particularly total hip arthroplasty (THA). Though, the overall incidence of HO following THA has been well-documented, it is often not reported by severity or by surgical approach.

QUESTIONS/PURPOSES

(1) What are the demographics of patients with HO? (2) What is the severity of HO following THA using the Brooker classification? (3) What is the incidence and class of HO following different THA approaches (anterior, posterior, posterolateral, anterolateral, superior, lateral, trans-gluteal)? (4) What are the number and training level of surgeons who performed each procedure?

METHODS

The PubMed, Embase, and Web of Science databases were queried, and PRISMA guidelines were followed. Qualitative and quantitative analyses were performed using Microsoft Excel.

RESULTS

We isolated 26 studies evaluating 6512 total hip arthroplasties (THA). The mean HO percentage overall was 28.8%, mostly Class I (54.2%) or Class II (29.6%). The highest percentage of HO was associated with the modified direct lateral (57.2%) and the traditional lateral (34.6%) approaches. The lowest HO percentages were identified following posterolateral (12.8%) and direct superior approaches (1%). Most studies reported a singular senior surgeon operating within the same approach for all patients.

CONCLUSIONS

The traditional lateral and modified direct lateral approaches to THA resulted in the highest percentage of HO postoperatively. However, most ossification cases were not clinically significant and did not strongly affect overall patient morbidity. Further studies are warranted to identify an association between severity of ossification and different arthroplasty approaches.

Low revision rate throughout the adoption of the direct superior approach in primary total hip arthroplasty: an analysis based on 1551 total hip arthroplasties from the Dutch Arthroplasty Register

BACKGROUND

Recently, surgeons introduced a minimally invasive modification on the classic posterolateral approach (PLA) in total hip arthroplasty (THA): the direct superior approach (DSA). We investigated the association between surgeon's experience and the risk of early revision of the DSA in primary THA, using data from the Dutch Arthroplasty Register (LROI).

METHODS

We retrieved all primary THAs performed using the DSA in 4 hospitals between 2016 and 2022 (n = 1551). Procedures were sorted in 5 groups using the date of operation and number of previous procedures per surgeon: 1-25; 26-50; 51-75; 76-100; >100. Subsequently, data from different surgeons were pooled together and the risk of revision was calculated via a multilevel time-to-event analysis.

RESULTS

The overall revision rate was 1.5% after a mean follow-up of 2 years. Patients from the 1-25 group had comparable risks of revision compared to patients in the >100 group (hazard ratio [HR] 1.0 [CI, 0.3-3.2]). The risk for patients in groups 26-50, 51-75 and 75-100 was also not statistically different from the >100 group (resp. HR 1.5 [CI, 0.5-5.0], 1.8 [CI, 0.5-6.4] and 0.5 [CI, 0.1-4.0]). Main reasons of revision were dislocation (0.5%) and infection (0.4%).

CONCLUSIONS

We did not identify an association between the surgeon's experience and the early risk of revision for the DSA in primary THA in the Netherlands. The DSA seems safe in the early adoption phases with a low risk of revision due to dislocation and revision for all other causes.

The Direct Superior Approach in Total Hip Arthroplasty: A Systematic Review

BACKGROUND

Evolution of the surgical approach for total hip arthroplasty (THA) has led to the development of the minimally invasive direct superior approach (DSA). It is hypothesized that the DSA reduces postoperative pain and hospital length of stay (LOS). We aimed to provide an overview of current evidence on clinical, functional, and radiological outcomes with respect to risk of revision, complications, pain scores, physical function, operative time, LOS, blood loss, radiological outcomes, and learning curve.

METHODS

A comprehensive search of Medline, Embase, Web of Science, Cochrane Central Register of Controlled Trials, and Google Scholar, reported according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses literature search extension guidelines, was conducted to identify studies evaluating clinical, functional, and radiological outcomes of the DSA. Quality assessment was performed using the Cochrane Risk of Bias tool and Newcastle-Ottawa Scale. The review protocol was prospectively registered in the International Prospective Registry of Systematic Reviews.

RESULTS

Seventeen studies were included, generally of moderate quality. Qualitative synthesis evidenced accurate implant positioning, short LOS, and a short learning curve. Conflicting findings were reported for postoperative complications compared with conventional approaches. Better functional outcomes were seen in the early postoperative period than the posterolateral approach (PLA). Outcomes such as blood loss and operative time exhibited conflicting results and considerable heterogeneity.

CONCLUSION

Based on moderate-certainty evidence, it is uncertain if the DSA provides short-term advantages over conventional approaches such as PLA. There is limited evidence on long-term outcomes post-THA using the DSA. Further studies and ongoing registry monitoring is crucial for continuous evaluation of its long-term outcomes.

LEVEL OF EVIDENCE

Level III. See Instructions for Authors for a complete description of levels of evidence.

Global mapping of institutional and hospital-based (Level II-IV) arthroplasty registries: a scoping review

PURPOSE

Four joint arthroplasty registries (JARs) levels exist based on the recorded data type. Level I JARs are national registries that record primary data. Hospital or institutional JARs (Level II-IV) document further data (patient-reported outcomes, demographic, radiographic). A worldwide list of Level II-IV JARs must be created to effectively assess and categorize these data.

METHODS

Our study is a systematic scoping review that followed the PRISMA guidelines and included 648 studies. Based on their publications, the study aimed to map the existing Level II-IV JARs worldwide. The secondary aim was to record their lifetime, publications' number and frequency and recognise differences with national JARs.

RESULTS

One hundred five Level II-IV JARs were identified. Forty-eight hospital-based, 45 institutional, and 12 regional JARs. Fifty JARs were found in America, 39 in Europe, nine in Asia, six in Oceania and one in Africa. They have published 485 cohorts, 91 case-series, 49 case-control, nine cross-sectional studies, eight registry protocols and six randomized trials. Most cohort studies were retrospective. Twenty-three per cent of papers studied patient-reported outcomes, 21.45% surgical complications, 13.73% postoperative clinical and 5.25% radiographic outcomes, and 11.88% were survival analyses. Forty-four JARs have published only one paper. Level I JARs primarily publish implant revision risk annual reports, while Level IV JARs collect comprehensive data to conduct retrospective cohort studies.

CONCLUSIONS

This is the first study mapping all Level II-IV JARs worldwide. Most JARs are found in Europe and America, reporting on retrospective cohorts, but only a few report on studies systematically.

No clinically relevant difference in patient-reported outcomes between the direct superior approach and the posterolateral or anterior approach for primary total hip arthroplasty: analysis of 37,976 primary hip arthroplasties in the Dutch Arthroplasty Registry

BACKGROUND AND PURPOSE

The direct superior approach (DSA) is a modification of the posterolateral approach (PLA) for total hip arthroplasty (THA). Patient-reported outcome measures (PROMs) of the DSA have not been investigated previously using nationwide data. Our aim was to assess PROMs after THA using the DSA compared with the PLA and, secondarily, with the anterior approach (DAA).

PATIENTS AND METHODS

In this population-based cohort study we included 37,976 primary THAs performed between 2014 and 2020 (PLA: n = 22,616; DAA: n = 15,017; DSA: n = 343) using Dutch Arthroplasty Registry data. PROMs (NRS pain, EQ-5D, HOOS-PS, and OHS) were measured preoperatively, and at 3 and 12 months postoperatively. Repeated measurements were analyzed using mixed-effects models, adjusted for confounders, to investigate the association between surgical approach and PROMs over time.

RESULTS

From baseline to 3 and 12 months, improvements for NRS pain scores, EQ-5D, and OHS were comparable for the DSA compared with the PLA or DAA. No difference was found in HOOS-PS improvement 3 months postoperatively between DSA and PLA (-0.2, 95% confidence interval [CI] -2.4 to 1.9) and between DSA and DAA (-1.7, CI -3.9 to 0.5). At 12 months postoperatively, patients in the DSA group had improved -2.8 points (CI -4.9 to -0.6) more in HOOS-PS compared with the DAA, but not with the PLA group (-1.0, CI -3.2 to 1.1).

CONCLUSION

Our study showed no clinically meaningful differences between the DSA and either PLA or DAA.

Revision risk by using the direct superior approach (DSA) for total hip arthroplasty compared with postero-lateral approach: early nationwide results from the Dutch Arthroplasty Register (LROI)

BACKGROUND AND PURPOSE

The direct superior approach (DSA) is a modification of the classic posterolateral approach (PLA) for total hip arthroplasty (THA), in which the iliotibial band and short external rotators are spared. The revision rate of the DSA has not been investigated previously using arthroplasty registry data. We examined the reasons and risk of revision of the DSA, compared with the direct anterior approach (DAA) and PLA.

PATIENTS AND METHODS

In this population-based cohort study we included 175,543 primary THAs performed between 2014 and 2020 (PLA, n = 117,576; DAA, n = 56,626; DSA, n = 1,341). Competing risk survival analysis and multivariable Cox proportional hazard analyses, adjusted for potential confounders, were performed.

RESULTS

After 3 years, crude revision rates due to any reason were 2.1% (95% confidence interval [CI] 1.3-3.3) for DSA, and 2.9% (CI 2.8-3.0) for PLA. Crude dislocation revision rates were 0.3% (CI 0.1-0.8) for DSA, versus 1.0% (CI 0.9-1.0) for PLA. Dislocation revision rate for DSA did not differ from DAA (0.3% [CI 0.2-0.3]). Multivariable Cox regression analysis demonstrated no overall difference in revision rates for the DSA (HR 0.6 [CI 0.4-1.09) compared with the PLA. Lower risk of revision due to dislocation was found in patients operated on through the DSA (HR 0.3 [0.1-0.9]) compared with the PLA.

CONCLUSION

Early nationwide results suggest that the DSA for total hip arthroplasty seems to show a tendency towards a lower risk of revision for dislocation but no overall reduced revision risk compared with the PLA.

Outcomes of direct superior approach and posterolateral approach for hemiarthroplasty in the treatment of elderly patients with displaced femoral neck fractures: A comparative study

Hemiarthroplasty is a surgical choice for super-aged patients with a high surgical risk and a sedentary lifestyle. The direct superior approach (DSA), a minimally invasive modification of the posterior approach, is rarely studied in hemiarthroplasty. The aim of the present study was to compare the clinical outcomes in elderly patients with displaced femoral neck fractures undergoing hemiarthroplasty via DSA with the conventional posterolateral approach (PLA). A total of 48 elderly patients with displaced femoral neck fractures who underwent hemiarthroplasty between February 2020 and March 2021 were retrospectively included in the study. Of them, 24 patients (mean age 84.54 ± 2.11 years) were treated with hemiarthroplasty via DSA (DSA group), while the other 24 patients (mean age 84.92 ± 2.15 years) were treated with hemiarthroplasty via PLA (PLA group). Clinical outcomes, perioperative data, and complications were recorded. There were no obvious differences in the baseline characteristics between the DSA and PLA groups, including age, gender, body mass index, Garden type, American Society of Anesthesiologists score, and hematocrit. Perioperative data showed that the length of the incision in the DSA group was smaller than that in the PLA group (p < 0.001). However, the duration of the operation and blood loss in the DSA group were longer and higher than those in the PLA group, respectively (p < 0.001). In addition, the DSA group had a shorter hospitalization time than the PLA group (p < 0.001). The visual analog scale score and Harris score 1 month postoperatively in the DSA group were better than those in the PLA group (p < 0.001). Moreover, there were no significant differences between the two groups in Harris score (for assessment dysfunction) 6 months postoperatively (p > 0.05). DSA is less invasive and has better clinical outcomes, which can allow an early return to daily living activities in elderly patients with displaced femoral neck fractures undergoing hemiarthroplasty.

How do dislocation rates differ between different approaches to total hip arthroplasty? A systematic review and meta-analysis

Background: Different surgical approaches for total hip arthroplasty (THA) exist, without predisposition when it comes to dislocation risk. The direct anterior approach (DAA) is thought to have reduced risk since soft tissue trauma is minimalized. Therefore, we assessed the dislocation risk for different surgical approaches, and the relative dislocation risk of DAA compared to other approaches. Methods: Six electronic databases were systematically searched for prospective studies reporting dislocation following THA. Proportion meta-analyses were performed to assess the dislocation rate for subgroups of the surgical approach. Meta-analysis for binary outcomes was performed to determine the relative risk of dislocation for the DAA compared to other approaches. Results: Eleven studies with 2025 patients were included (mean age 64.6 years, 44% male, mean follow-up 10.5 months), of which four studies were also used in the risk ratio meta-analysis. Overall dislocation rate was 0.79% (95% CI 0.37–1.69). Subgroup analyses showed that most dislocations occurred in the posterior approaches group (1.38%), however non-significant. Furthermore, the DAA emerged with a non-significant lower risk of dislocation (RR 0.37, 95% CI 0.05–2.46) compared to other surgical approaches. Conclusion: Current literature shows non-significant predisposition for a surgical approach to THA regarding dislocation risk. To what extent patient characteristics influence the risk of dislocation could not be determined. Future research should focus on this, as well as on the influence of a surgeon's experience with a specific approach.

Constrained liners revisited: favourable mid-term results in patients with high-risk of dislocation: technical considerations for the optimal outcome

BACKGROUND

The outcomes of constrained liners (CLs) in total hip arthroplasty (THA) remain inconclusive. We evaluated the mid-term performance of CLs in a consecutive series of high-risk dislocation patients undergoing primary or revision THA performed by a single surgeon. The survival, dislocation rate, complications, and functional patients' scores were assessed. Surgical tips to enhance outcomes were reviewed.

METHODS

45 patients who received the Trident Tripolar CL between 2010 to 2019 were retrospectively evaluated from Arthroplasty Registry Thessaloniki. There were 17 primary and 28 revision THAs. The primary indications for using CL were severe abductor insufficiency or comorbidities, increasing the dislocation risk in primary, and recurrent dislocation or abductor insufficiency in revision THAs. The mean patient's age was 68.5 (±14.5) years, and the mean follow-up 3.81 (±1.66) years.

RESULTS

There were 2 dislocations and 1 deep infection in the revision group. For any reason, the cumulative 6-year survival rate was 93.3%, 100% for primary, and 89.3% for revision THAs. The mean overall CL survival was 76.3 months for any reason (95% CI, 68.1-84.5) and 80.5 months for dislocation (95% CI, 75.8-85.2). The mean postoperative functional scores were significantly improved (p < 0.001) at the latest follow-up.

CONCLUSIONS

CLs can provide hip stability and durable fixation in selected low-demand patients with high-risk for dislocation after primary and revision THA at mid-term follow-up. Careful patient selection and the refined surgical technique aiming at the neutral liner position and considering the high CLs' offset relative to stem-neck impingement are necessary to maximise outcomes.

Superior Transverse Atraumatic Reconstruction (STAR) approach provides a better-compared outcome to standard Direct Superior Approach (DSA): a matched, prospective comparative single-surgeon study

INTRODUCTION

The Direct Superior Approach (DSA) is a muscle-sparing hip approach that does not protect the piriformis and the other short external rotators. We present a DSA modification we named STAR (Superior Transverse Atraumatic Reconstruction), which has DSA advantages but always preserves piriformis. Our study compared the early postoperative, radiological, and functional results of patients undergoing primary total hip arthroplasty (THA) through the STAR approach with a matched DSA group performed by a senior surgeon.

METHODS

Each group, DSA, and STAR included 200 elective primary unilateral THAs performed by the surgeon between 2016-2017 and 2020-2021, respectively. Patients were included in both groups using the same inclusion criteria. Both groups were matched for age and sex. The same postoperative pain management, chemoprophylaxis, and physiotherapy protocols were followed in both groups. Two independent orthopaedic surgeons performed the clinical and radiological follow-up.

RESULTS

The STAR group had significantly lower mean incision length (p = 0.042) and hospital stay (p = 0.002) than the DSA group. The mean intraoperative blood loss (p = 0.085) and the need for blood transfusion (p = 0.228) were less for the STAR than the DSA group. The mean postoperative functional scores improvement was significantly higher for the STAR than the DSA group at the end of the first and third postoperative months.

CONCLUSIONS

The STAR approach offers earlier functional improvement, shorter hospital stay and less transfusion need than DSA for patients undergoing primary THA. Both approaches showed a limited complication risk and an outstanding acetabular and femoral access enabling the procedure.

Earlier functional recovery and discharge from hospital for THA patients operated on via direct superior compared to standard posterior approach: a retrospective frequency-matched case-control study

BACKGROUND

The direct superior hip approach (DSA) has been less researched than other approaches in the literature. We retrospectively compared the early postoperative and functional outcomes of patients with hip osteoarthritis undergoing total hip arthroplasty (THA) via DSA with a matched control group using a standard posterior approach (SPA).

METHODS

The DSA group comprised 100 THAs performed via DSA by a senior surgeon between January 2018 and May 2019. Patients with primary osteoarthritis and ASA score ⩽3 who were eligible for surgery were included. The DSA group was compared to a matched cohort of 100 patients operated on with a SPA in the same period by another chief surgeon. Patients were matched for age, sex, and ASA score. All patients received the same postoperative chemoprophylaxis, pain management and physiotherapy. 2 independent attending arthroplasty surgeons assessed the incision length, operative time, blood loss, hospital stay, and complications. VAS, HHS, and HOOS scores were also evaluated for a year postoperatively.

RESULTS

Mean incision length and hospital stay were significantly lower in the DSA group. DSA patients had non-significantly lower intraoperative blood loss, transfusion needs, and postoperative pain than SPA patients. Mean operation time and complication rate did not differ between groups. The DSA group demonstrated significantly greater functional scores than the SPA group at the first postoperative month. No differences in scores were recorded following the third month.

CONCLUSIONS

The DSA approach may provide earlier functional recovery and hospital discharge for THA patients compared with SPA. DSA was equivalent to SPA concerning pain and blood loss, showing minimal complication rates.

Survival of monoblock RM vitamys compared with modular PINNACLE cups: mid-term outcomes of 200 hips performed by a single surgeon

INTRODUCTION

Monoblock cups have theoretical advantages over modular cups; however, their superiority in terms of survival has not been confirmed in comparative studies.

METHODS

We compared the mid-term survivorship of 107 RM Pressfit vitamys monoblock cups (Mathys Ltd., Bettlach, Switzerland) with 93 modular pressfit Pinnacle cups (DePuy Synthes, Warsaw, IN, USA). All cases were registered in the Arthroplasty Registry Thessaloniki and performed by a senior surgeon through the same approach between 2013 and 2014. The groups were comparable in sex distribution, preoperative diagnosis, follow-up, cup diameter, head diameter, type and use of screws, HOOS and HSS preop scores; the recipients of RM cup were significantly younger.

RESULTS

3 sockets were revised. The 6-year survival for any reason was 99.1% for the RM and 97.8 % for the PINNACLE group. There was no difference in survival for aseptic loosening and any reason between groups (log-rank test p = 0.921 and p = 0.483, respectively). The age (95% CI, 0.79-1.1), sex (95% CI, 0.2-45.0), cup diameter (95% CI, 0.18-1.1), head diameter (95% CI, 0.004-6.2), preoperative diagnosis and use of screws (95% CI, 0.02-4.3), did not influence hazard ratio for revision between groups. HHS and HOOS were comparable at the last follow-up.

CONCLUSIONS

Our study demonstrated that both cup designs had similar revision rates at mid-term follow-up, regardless the fact that the RM vitamys was used in a cohort of younger patients; which according to the literature would have led to earlier failures. Further long-term data are needed to evaluate the superiority of RM vitamys in the clinical setting, especially in the young.

Direct superior approach for total hip arthroplasty

AIMS

The purpose of this study was to compare the clinical, radiological, and patient-reported outcome measures (PROMs) in the first 100 consecutive patients undergoing total hip arthroplasty (THA) via a direct superior approach (DSA) with a matched group of patients undergoing THA by the same surgeon, using a posterolateral approach (PLA).

METHODS

This was a retrospective single surgeon study comparing the first 100 consecutive DSA THA patients with a matched group of patients using a standard PLA. Case notes were examined for patient demographics, length of hospital stay, operating time, intra- and postoperative complications, pain score, satisfaction score, and Oxford Hip Score (OHS). Leg length discrepancy and component positioning were measured from postoperative plain radiographs.

RESULTS

The DSA patients had a shorter length of hospital stay (mean 2.09 days (SD 1.20) DSA vs 2.74 days (SD 1.17) PLA; p < 0.001) and shorter time to discharge from the inpatient physiotherapy teams (mean 1.44 days (SD 1.17) DSA vs 1.93 days (SD 0.96) PLA; p < 0.001). There were no differences in operating time (p = 0.505), pain levels up to postoperative day 1 (p = 0.106 to p =0.242), OHS (p = 0.594 to p = 0.815), satisfaction levels (p = 0.066 to p = 0.299), stem alignment (p = 0.240), acetabular component inclination (p < 0.001) and anteversion (p < 0.001), or leg length discrepancy (p = 0.134).

CONCLUSION

While the DSA appears safe and was not associated with a significant difference in PROMs, radiological findings, or intraoperative or postoperative complications, a randomized controlled trial with functional outcomes in the postoperative phase is needed to evaluate this surgical approach formally. Cite this article: Bone Joint J 2021;103-B(3):500-506.

Lewinnek Safe Zone References are Frequently Misquoted

BACKGROUND

Optimal acetabular component orientation in total hip arthroplasty (THA) is a necessity in achieving a stable implant. Although there has been considerable debate in the literature concerning the safe zone, to date, there has not been any review to determine if these references are consistent with the definition applied by Lewinnek et al. in 1978. Therefore, this article aims to examine the available literature in the PubMed database to determine how often a correct reference to the safe zone as defined by Lewinnek was applied to discussions regarding THA.

METHODS

A search for literature in the PubMed database was performed for articles from 1978 to 2019. Search criteria included terms 'Lewinnek,' 'safe zone,' and 'total hip arthroplasty.' Exclusions included abstract-only articles, non-English articles, articles unrelated to THA, and those lacking full content.

RESULTS

A review of literature yielded 147 articles for inclusion. Overall, only 11% (17) cited the Lewinnek article correctly. Forty-five percent (66) of articles referenced measurements in the supine position, 18% (26) referenced other positions, and 37% (55) did not specify. Nineteen percent (28) reported measurements of the acetabular cup orthogonal to the anterior pelvic plane, while 73% (108) did not, and 7% (11) did not specify. Twenty-three percent (34) measured from computed tomography scans instead of other methods.

CONCLUSIONS

In the discussion of the safe zone regarding THA, only 11% of articles listed are consistent with the definition established by Lewinnek. This warrants further investigation into a consistent application of the term and its implications for THA implant stability and dislocation rates.

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

Background

Limited 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).

Methods

Immediate 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.

Results

Agreement 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.

Conclusions

DAA enables correct implantation and effective cementation of straight femoral stems. A high-quality cement mantle can be achieved using DAA even in obese patients.

No Learning Curve of the Direct Superior Approach in Total Hip Arthroplasty

OBJECTIVES

To assess the learning curve of the direct superior approach (DSA) for total hip arthroplasty (THA) and to compare surgical, clinical, and radiological results with a matched control group using the mini posterior approach (MPA).

METHODS

A prospective cohort study was performed from October 2016 to May 2017 including our first 52 patients undergoing THA using the DSA. Patients with primary osteoarthritis or osteonecrosis and a body mass index (BMI) < 35 who were eligible for surgery were included. As a control group, 52 patients who underwent the MPA were included, matched based on age, BMI, and ASA classification. In the DSA group, damage to the iliotibial tract and the distal external rotators, including the external obturator and quadriceps femoris muscles, was avoided. Outcome measures were collected, including surgical time, blood loss, postoperative pain, length of stay, implant position, use of walking aids, patient reported outcome measures (PROM), and complications. Unpaired t-tests were used to analyze differences between the DSA and the MPA group in surgical time, blood loss, length of stay, and acetabular and femoral component position. χ² -tests were used to analyze mobility and the number of complications. Two-way repeated measures ANOVA was used to analyze pain scores and PROM between the DSA and the MPA groups.

RESULTS

The mean surgical time of 61 min (SD 8) in the DSA group was longer (P < 0.001) compared to that in the MPA group, 46 min (SD 12). No differences were found in blood loss, postoperative pain, or mean length of stay in the hospital. After 6 weeks, 94% of the patients in the DSA group were able to walk inside their home without walking aids compared to 90% in the MPA group. The mobility scores were not different after follow up of 6 weeks and 1 year (P = 0.12 and P = 0.36 respectively). All PROM improved postoperatively in both the DSA and the MPA group (P < 0.01). Acetabular cup and femoral stem position were not compromised by the DSA. Complications included two Vancouver B2 periprosthetic fractures in the DSA group, of which there was one surgical-related fracture and one fracture after a traffic accident. Complications in the MPA group included one periprosthetic fracture, two hip dislocations, and one ischial neuropathy. No infections or thromboembolic events were observed. The 1-year complication rate was not different between the MPA and DSA groups (P = 0.40).

CONCLUSION

The DSA can be safely introduced as no learning curve in the prosthesis position or the complication rate was found.