EOS Imaging is Accurate and Reproducible for Preoperative Total Hip Arthroplasty Templating

BackgroundTemplating is a critical part of preoperative planning for total hip arthroplasty (THA). The accuracy of templating on images acquired with EOS is unknown. This study sought to compare the accuracy and reproducibility of templating for THA using EOS imaging to conventional digital radiographs.MethodsForty-three consecutive primary unilateral THAs were retrospectively templated, six months postoperatively, using preoperative 2D EOS imaging and conventional radiographs. Two blinded observers templated each case for acetabular and femoral component size and femoral offset. The retrospectively templated sizes were compared to the sizes selected during surgery. Interobserver agreement was calculated, and the influence of demographic variables was explored.ResultsEOS templating predicted the exact acetabular and femoral size in 71% and 66% of cases, respectively, and to within one size in 98% of cases. The acetabular and femoral component size was more likely to be templated to the exact size using EOS compared to conventional imaging (P < .05). The femoral component offset choice was accurately predicted in 83% of EOS cases compared to 80% of conventional templates (P = .341). Component size and offset were not influenced by patient age, gender, laterality, or BMI. Interobserver agreement was excellent for acetabular (Cronbach’s alpha = 0.94) and femoral (Cronbach’s alpha = 0.96) component size.ConclusionsPreoperative templating for THA using EOS imaging is accurate, with an excellent interobserver agreement. EOS exposes patients to less radiation than traditional radiographs, and its three-dimensional applications should be explored as they may further enhance preoperative plans.     

Comparisons of Preoperative Three-Dimensional Planning and Surgical Reconstruction in Primary Cementless Total Hip Arthroplasty

Reconstruction of important parameters such as femoral offset and torsion is inaccurate, when templating is based on plain x-rays. We evaluate intraoperative reproducibility of pre-operative CT-based 3D-templating in a consecutive series of 50 patients undergoing primary cementless THA through an anterior approach. Pre-operative planning was compared to a postoperative CT scan by image fusion. The implant size was correctly predicted in 100% of the stems, 94% of the cups and 88% of the heads (length). The difference between the planned and the postoperative leg length was 0.3 + 2.3 mm. Values for overall offset, femoral anteversion, cup inclination and anteversion were 1.4 mm ± 3.1, 0.6° ± 3.3°, − 0.4° ± 5° and 6.9° ± 11.4°, respectively. This planning allows accurate implant size prediction. Stem position and cup inclination are accurately reproducible.     

Interobserver and Intraobserver Reliability of Three-Dimensional Preoperative Planning Software in Total Hip Arthroplasty

Background

The purpose of this study is to clarify interobserver and intraobserver reliabilities of the three-dimensional (3D) templating of total hip arthroplasty (THA).

Measurement Techniques for Leg Length Discrepancy in Total Hip Arthroplasty: A Systematic Review of Reliability and Validity

BackgroundTotal hip arthroplasty (THA) carries a substantial litigative burden. THA may introduce leg length discrepancy (LLD), necessitating a valid and reliable technique for LLD measurement. This study investigates the reliability and validity of techniques quantitively measuring LLD in both pre- and post-THA.MethodsEmbase and MEDLINE databases were searched following Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines for articles assessing either the validity or reliability of LLD measurement techniques. Data was pooled using random effects meta-analysis to derive reliability estimates. Study quality was assessed using the Brink and Louw checklist.ResultsForty-two articles with 2059 participants were included. Thirty-three investigated reliability and 25 validity. Reliability displayed high heterogeneity. Poor to excellent intra-rater reliability was reported for antero-posterior pelvis radiographs, moderate to excellent for computed tomography scanograms, and good to excellent for clinical methods and teleradiography, and excellent for bi-planar radiography (BPR). Poor to excellent inter-rater reliability was reported for antero-posterior pelvis radiographs and clinical methods, moderate to excellent for teleradiography, good to excellent for computed tomography scanogram and excellent for BPR. The tape measure method is a valid clinical measure of LLD whilst markerless motion analysis and the block method are not. Imaging techniques are appropriately cross-validated with the exception of BPR.ConclusionThe reported intra- and inter-rater reliability for most measurement techniques vary widely. The tape measure method is a valid clinical measurement of LLD. Imaging techniques have been appropriately cross-validated, with the exception of BPR, although they lack validation against a common reference technique.     

Conversion of Arthrodesis to Total Hip Arthroplasty: Clinical Outcome,Complications, and Prognostic Factors of 21 Consecutive Cases

Background

Although the results of hip arthrodesis compare favorably with those of total hip arthroplasty (THA) in younger patients, long-term consequences such as osteoarthritis of the neighboring joints may necessitate conversion of the arthrodesis to THA.

Questions/Purposes

The purpose of the present study is to assess mid-term clinical outcome and self-perceived improvement in patients who underwent conversion at our department. Secondary aims were incidence of complications and association between patient characteristics and characteristics of the fusions with the outcome of the procedure.

Patients and Methods

The study sample comprised 21 cases in 20 patients. Minimum follow-up was 3 years (mean, 8 ± 6.5 years) in 20 cases. Thirteen patients had surgical hip fusions and 7 (8 hips) had nonsurgical fusions. Mean age at the time of conversion was 58.5 years.

Results

Nineteen out of 21 cases had functioning implants at the latest follow-up visit. According to the Merle d’Aubigné scale, outcome was considered excellent, very good, or good in 15 cases. Lower back pain was reduced in all patients. All but two patients were satisfied after the conversion. The main complications observed included incomplete removal of bone block, intra-operative fractures, dislocation and damage to the femoral artery. Time to conversion and type of fusion had no significant correlation with the clinical outcome.

Conclusions

Conversion THA is a challenging but successful procedure according to the mid-term clinical outcome observed. Our study suggests that, prognostic factors should be used with caution when establishing indications and post-surgical expectations.

Electronic supplementary material

The online version of this article (doi:10.1007/s11420-013-9330-3) contains supplementary material, which is available to authorized users.     

MAASH Technique for Total Hip Arthroplasty: A Capsular Work

Background

Dislocation and leg length discrepancy are major complications following total hip arthroplasty (THA). Many surgical approaches for THA have been described, but none suggest a capsular incision that assures good exposure while maintaining adequate capsule integrity in closure.

Purposes

Modified anterolateral approach for stable hip (MAASH) is a modification of the classical Hardinge approach, but specifically preserves the anterior iliofemoral lateral ligament and pubofemoral ligament excising the “weak area” of the capsule, in the so called “internervous safe zone” and introducing the “box concept” for the anterior approach to the hip. This is the main difference of the MAASH approach. This technique can be used as a standard for all THA standard models, but we introduce new devices to make it easier.

Methods

From November 2007 to May 2012, data were collected for this observational retrospective consecutive case study. We report the results of 100 THA cases corresponding to the development curve of this new concept in THA technique.

Results

MAASH technique offers to hip surgeons, a reliable and reproducible THA anterolateral technique assuring accurate reconstruction of leg length and a low rate of dislocation. Only one dislocation and six major complications are reported, but most of them occurred at the early stages of technique development.

Conclusion

MAASH technique proposes a novel concept on working with the anterior capsule of the hip for the anterolateral approach in total hip arthroplasty, as well as for hemiarthroplasty in the elderly population with high dislocation risk factors. MAASH offers maximal stability and the ability to restore leg length accurately.

Electronic supplementary material

The online version of this article (doi:10.1007/s11420-013-9332-1) contains supplementary material, which is available to authorized users.     

In Vivo Determination and Comparison of Total Hip Arthroplasty Kinematics for Normal,Preoperative Degenerative,and Postoperative Implanted Hips

BackgroundThe study objective is to analyze subjects having a normal hip and compare in vivo kinematics to subjects before and after receiving a total hip arthroplasty.MethodsTwenty subjects, 10 with a normal hip and 10 with a preoperative, degenerative hip were analyzed performing normal walking on level ground while under fluoroscopic surveillance. Seven preoperative subjects returned after receiving a total hip arthroplasty using the anterior surgical approach by a single surgeon. Using 3-dimensional to 2-dimensional registration techniques, joint models were overlayed on fluoroscopic images to obtain transformation matrices in the image space. From these images, displacements of the femoral head and acetabulum centers were computed, as well as changes in contact patches between the 2 surfaces throughout the gait cycle.ResultsImplanted hips experienced the least amount of separation, compression, and overall sliding throughout the entire gait cycle, but they did show signs of edge loading contact patterns. Conversely, the degenerative hips experienced the most compression, sliding, and separation, with the maximum amount of sliding being 6.9 mm. The normal group ranged in the middle, with the maximum amount of sliding being 1.75 mm.ConclusionCurrent analysis revealed trends that degenerative hips experience more abnormal hip kinematics that leads to higher articulating surface forces and stresses within the acetabulum. None of the implanted hips experienced hip separation.     

Usefulness of a Simple Preoperative Planning Technique using Plain X‐rays for Direct Anterior Approach for Total Hip Arthroplasty

ObjectiveTo examine the accuracy, reliability, and reproducibility of a simple preoperative planning technique using plain X‐rays.MethodsA retrospective analysis of 96 consecutive cases of primary direct anterior approach (DAA)‐total hip arthroplasty (THA) from July 2015 to December 2018 was performed. The 96 patients included 24 males and 72 females, with an average age of 70 years. The standard AP pelvis radiographs with the patients'' hips extended and internally rotated were obtained pre‐ and postoperatively. The preoperative planning was also completed on the standardized AP pelvic radiographs. The prearranged cup positioning was radiologically measured intraoperatively using fluoroscopy. The correct leg length was assessed intraoperatively, which was compared with the preoperative planning. The component positioning was measured by three independent researchers. Two of the researchers completed the measurements three times, and intra‐observer and inter‐observer reliability were calculated. All patients received at least 6 months follow‐up (6 months–4 years).ResultsIn all cases, the median leg length discrepancy (LLD) was 4.4 mm (range 1.6–15.9 mm), and 84 patients had an LLD smaller than 10 mm, of which 58 patients had an LLD of less than 5 mm. None of the patients had a critical LLD of 2 cm or larger. The multivariable logistic regression for LLD (safe range: yes/no) with the co‐variables including gender, ASA classification, type of cup, the surgeon''s experience level, and the presence of a total hip arthroplasty (THA) on the contralateral side did not present statistical significance. The median angle of the inclination of the acetabular component (IA) was 42.3° (range: 28.7°–52.2°). Ninety‐one patients were within the defined safe range. The hit ratio for the cup to be within the safe zone was significantly higher for the Pinnacle cups than that for the Continuum cups (P < 0.05). However, there was no significant difference in gender, ASA classification, the surgeon''s experience level, and the presence of a total hip arthroplasty (THA) on the contralateral side. The median of its anteversion (AA) was 20.6° (range: 10.6°–40.1°). Only 41 patients were within the defined safe range. None of the co‐variables presented a statistical significance affecting the AA of the cup positioning. Meanwhile, the average fluoroscopy time for the cup positioning (n = 86, missing data in 10 cases) was 4 seconds (range: 1–74), with most of the patients (97.9%) having a fluoroscopy time of fewer than 20 seconds.ConclusionsThe combination of correct preoperative planning and standardized intraoperative measurements can reestablish right leg length and assure the correct cup positioning.     

Comparison of Component Placement Accuracy Using Two Intraoperative Fluoroscopic Grid Technologies During Direct Anterior Total Hip Arthroplasty

BackgroundIntraoperative fluoroscopy is beneficial when performing total hip arthroplasty (THA) via the direct anterior approach; however, image distortion may influence component placement. A manual gridding system (MGS) and a digital gridding system (DGS) are commercially available, aimed at visually representing or correcting image distortion. Therefore, the purpose of this study is to compare component placement accuracy following direct anterior approach THA when intraoperative fluoroscopy was supplemented with MGS or DGS.MethodsA retrospective evaluation of acetabular cup abduction (ABD), leg length discrepancy (LLD) and global hip offset difference (GHO) was completed for consecutive patients from 6 week post-THA weight-bearing radiographs. The predefined target LLD and GHO was <10 mm and ABD target was 45° ± 10°. Differences between MGS and DGS were determined by independent t-tests.ResultsThe MGS (250 patients, 315 hips) and DGS (183 patients, 218 hips) achieved targeted ABD in 98.7% and 96.8% of cases, respectively, and ABD was significantly lower in the MGS group (45.14 ± 4.03° and 47.01 ± 4.39°, respectively) (P < .001). Compared to MGS, the DGS group averaged significantly higher GHO (3.64 ± 2.44 and 4.45 ± 2.73 mm, respectively, P = .002) but was not significantly different regarding LLD (2.92 ± 2.55 and 3.19 ± 2.46 mm, respectively, P = .275). No significant group difference was noted for percentage within the targeted LLD and GHO; however, 93.5% of DGS and 97.6% of MGS achieved all three (P = .031).ConclusionThe use of both the MGS and DGS resulted in consistent component placement within the predefined target zone. Although the MGS appeared to be slightly more consistent, these differences are unlikely to be clinically significant.     

A Simple Method Using a PACS to Minimize Leg Length Discrepancy in Primary THA : A Method to Minimize Leg Length Discrepancy

We determined whether a PACS-based method (head-lesser trochanter distance [HLD]) better equalized leg length discrepancy (LLD) after primary THA than a conventional method. We retrospectively reviewed 312 patients (379 hips) with osteonecrosis or primary osteoarthritis who underwent primary cementless THA: 198 patients (240 hips) underwent THA using the HLD method, while the conventional group consisted of 114 patients (139 hips) in whom we measured with the method of McGee and Scott. We then compared the LLDs in the two groups. We observed no difference in the mean postoperative LLD. A higher percentage of patients in the HLD group had an LLD less than 6 mm: 81% vs 68% hips, respectively. HLD method decreases the possibility of an LLD over 6 mm after THA.     

Impact of Preoperative Anemia Severity on Primary Total Hip Arthroplasty Outcomes

BackgroundPreoperative anemia (POA) is a significant predictor for adverse outcomes in primary total hip arthroplasty (THA). Current literature has studied POA stratified by severity. This study aims to find a threshold preoperative hemoglobin (Hb) value for increased risk of adverse outcomes in THA.MethodsThis is a retrospective analysis of primary THA patients with preoperative Hb values from 2014 to 2021 from an academic orthopedic specialty hospital. Demographics, surgical data, and postoperative outcomes were collected. Patients without preoperative Hb values within the electronic health record system or values acquired >30 days preoperatively were excluded. Patients were grouped based on POA severity using World Health Organization criteria. Secondary analysis using discrete preoperative Hb values was performed. P-values were calculated using analysis of variance/Kruskal-Wallis and chi-squared/Fisher’s exact testing with P < .05 considered significant.ResultsA total of 1347 patients were included: 771 (57.2%) patients with POA and 576 (42.8%) with normal preoperative Hb. In the POA group, 292 (37.9%) were mild, 445 (57.7%) moderate, and 34 (4.4%) severe. Increased length of stay was seen in moderate (3.9 ± 4.3 vs 2.4 ± 2.1, P < .001) and severe (5.0 ± 3.4 vs 2.4 ± 2.1, P < .0001) groups compared to control. The severe group had higher 90-day readmission and revision rates compared to control. Analysis by discrete Hb values showed increased length of stay in Hb values <11 g/dL and a greater proportion of patients with Hb values <12 g/dL were discharged to skilled nursing facilities.ConclusionPatients with preoperative Hb <12 g/dL should be assessed for other risk factors that may predispose them to postoperative complications. Further investigation is warranted to develop more robust perioperative management strategies for POA patients undergoing THA.Level III EvidenceRetrospective Cohort Study.     

Total Hip Arthroplasty Using Imageless Computer-Assisted Hip Navigation: A Prospective Randomized Study

In a prospective randomized study of two groups of 65 patients each, we compared the acetabular component position when using the imageless navigation system compared to the freehand conventional technique for cementless total hip arthroplasty. The position of the component was determined postoperatively on computed tomographic scans of the pelvis. There was no significant difference for postoperative mean inclination (P = 0.29), but a significant difference for mean postoperative acetabular component anteversion (P = 0.007), for mean deviation of the postoperative anteversion from the target position of 15° (P = 0.02) and for the outliers regarding inclination (P = 0.02) and anteversion (P < 0.05) between the computer-assisted and the freehand-placement group. Our results demonstrate the importance of imageless navigation for the accurate positioning of the acetabular component.     

Substantial Preoperative Work Is Unaccounted for in Total Hip and Knee Arthroplasty

BackgroundThe Centers for Medicare and Medicaid Services has recently designated the codes for total hip and knee arthroplasty as misvalued and has asked the Relative Value Scale Update Committee (RUC) to review the work required to perform these procedures. Although other studies have reported time spent on perioperative and postoperative care, time spent on coordinating and performing preoperative care is not included in current RUC methodology and has yet to be addressed in literature.MethodsWe prospectively tracked a consecutive series of 438 primary total hip arthroplasty and total knee arthroplasty patients by one of the 5 surgeons over a 3-month period. Each clinical staff member tracked the amount of time to perform each preoperative care task from the last clinic visit until day of surgery. Data were analyzed separately between providers and ancillary medical staff.ResultsAlthough the current RUC review includes 40 minutes of preservice time on the day of surgery, surgeons spent an average of an additional 43.2 minutes while physician assistants and nurse practitioners spent an additional 97.9 minutes per patient on preoperative care prior to that time. Ancillary medical staff spent a mean of 110.2 minutes per patient. The most common tasks include preoperative phone calls, templating and surgical planning, and preoperative patient education classes.ConclusionSurgeons and advanced practice providers spend nearly 2 hours per arthroplasty patient on preoperative care not accounted for in current RUC methodology. As readmissions, hospital stay, and complication rates continue to decline, Centers for Medicare and Medicaid Services should consider the substantial work required during the preoperative phase to allow for these improved outcomes.     

重度先髋脱位全髋置换术中肢体延长长度的探讨

目的探讨全髋关节置换术(total hip arthroplasty,THA)治疗重度先天性髋关节脱位(developmental dys-plasia hip,DDH)时下肢可以延长的安全范围。方法基础研究部分:20只狗建立后肢延长后神经、血管损伤模型,通过神经电生理、组织学和血流动力学的方法,了解其神经损伤和血管损伤与牵拉的关系。临床研究部分:29例(32髋)重度DDH患者,26髋行单纯THA手术,6髋行THA、粗隆下截骨术。术后采用Harris评分、肌电图、血管超声等方法检查神经血管损伤,平均随访6个月。结果动物实验:延长长度超过肢体原有长度6%时,神经电生理有所表现,未发生血管损伤。临床试验:29例患者术前Harris评分为(32.98±8.51)分,术后随访6周,28例患者(脱漏1例)Harris评分为(91.26±3.57)分,肢体延长长度(3.3±1.15)cm,最长延长5.9 cm。有5例出现神经传导速度减慢,6例出现感觉神经传导减慢,4例延长超过下肢长度6%的患者均出现感觉及运动神经传导异常、肌电图未见自发电位,3例患者在术后出现肢体麻木,复诊时症状消失;血管损伤均未发生。结论 THA手术治疗重度DDH时,肢体延长不超过下肢长度的6%是安全的。     

The Impact of Leg Length Discrepancy on Patient Satisfaction and Functional Outcome Following Total Hip Arthroplasty

A series of 191 patients undergoing THA with a standardised stem were studied. The effect of leg length discrepancy (LLD) on patient function (Oxford Hip Score), health measures (Short Form 12) and satisfaction (Self-Administered Patient Satisfaction Scale) at a mean 3.8 years of follow up (range 3.3 to 4.9) is reported. 8.9% of cases had shortening, 0.5% no LLD and 90.6% had lengthening. In 21.5% the LLD was more than 10 mm, in 37.1% 5–10 mm, and in 40.9% 0–5 mm. There was no significant difference in patient reported outcome measures (PROMs) according to LLD. Correlation of recorded measurements between multiple observers was excellent (0.93). LLD following total hip arthroplasty remains common but in this series, was not correlated with PROMs.     

Early Outcome Comparison Between the Direct Anterior Approach and the Mini-Incision Posterior Approach for Primary Total Hip Arthroplasty: 150 Consecutive Cases

This study evaluated early postoperative results of 150 consecutive primary total hip arthroplasties performed by a single surgeon; 50 from mini-incision posterior approach, 50 during the learning curve for the direct anterior approach, and 50 subsequent cases when the approach was routine. The anterior approach groups had significantly reduced hospital length of stays (2.9 and 2.7 days versus 3.9 days for the posterior group; P < 0.0001) and discharge to home versus rehab was more likely (80% and 84% in anterior groups, 56% in posterior group; P = 0.0028). In the anterior groups, there was significantly less use of assistive devices and narcotics at 6 weeks, and pain was significantly lower. Primary total hip arthroplasty using the anterior approach allows for superior recovery in a matched cohort of patients.     

Cost-Effectiveness of Preoperative Spinal Imaging Before Total Hip Arthroplasty

BackgroundThe risk of instability, dislocation, and revision following total hip arthroplasty (THA) is increased in patients with abnormal spinopelvic mobility. Seated and standing lateral lumbar spine imaging can identify patients with stiff/hypermobile spine (SHS) to guide interventions such as changes in acetabular cup placement or use of a dual-mobility hip construct aimed at reducing dislocation risk.MethodsA Markov decision model was created to compare routine preoperative spinal imaging (PSI) to no screening in patients with and without SHS. Screened patients with SHS were assumed to receive dual-mobility hardware while those without SHS and nonscreened patients were assumed to receive conventional THA. Cost-effectiveness was determined by estimating the incremental cost-effectiveness ratio. Effectiveness measured as quality-adjusted life years (QALYs), with $100,000 per additional QALY as the threshold for cost-effectiveness. Sensitivity analyses were performed to determine the robustness of the base-case result.ResultsThe screening strategy with PSI had a lifetime cost of $12,515 and QALY gains of 16.91 compared with no-screening ($13,331 and 16.77). The PSI strategy reached cost-effectiveness at 5 years and was dominant (ie, less costly and more effective) at 11 years following THA. In sensitivity analyses, PSI remained the dominant strategy if prevalence of SHS was >1.9%, the cost of PSI was <$925, and the cost of dual-mobility hardware exceeded the cost of conventional hardware by <$2850.ConclusionScreening patients for SHS prior to THA with PSI is both less costly and more effective and should be considered as part of standard presurgical workup.     

同期双侧全髋关节置换术的临床观察

目的探讨同期双侧人工全髋关节置换术的疗效。方法2000年8月至2005年3月,对10例(20髋)患者行双侧全髋关节置换术。其中男8例16髋,女2例4髋;年龄25~65岁,病程1~30年(平均4.8年)。术前髋关节Harris评分12~45分,平均27分。其中7例采用Smith-Peterson切口,3例采用后路M oore切口。手术时间为3.4~5.5 h,平均4.5 h,术中输血600~1600 mL,平均1000 mL。结果10例均获6个月~5年3个月,平均18个月随访,髋关节术后Harris评分70~100分,平均86分,较术前平均提高59分(27~86分),差异有统计学意义(P<0.05)。除1例患者于术后1个月因心脏病死亡外,其余患者术后均无感染、肺栓塞、深静脉栓塞、假体松动、假体下沉及脱位等并发症发生。患者均能独立行走,自理生活。结论同期双侧人工全髋关节置换术是一种安全有效的手术,充分的术前准备,慎重选择病例,严格的假体安装标准,有效地风险防范是手术成功的关键。     

Incidence and Risk Factors of Iliopsoas Tendinopathy After Total Hip Arthroplasty: A Radiographic Analysis of 1,602 Hips

BackgroundIliopsoas tendinopathy (IPT) can cause persistent groin pain and lead to dissatisfaction after total hip arthroplasty (THA). This study aimed to report the characteristics, incidences, risk factors, and treatment outcomes of IPT after THA.MethodsWe reviewed primary THAs performed at a single institution between January 2012 and May 2018. Clinical and radiographic analyses were performed on 1,602 THAs (1,370 patients). Patient characteristics, component sizes, inclination and anteversion angles, and antero-inferior cup prominence (≥8 millimeters (mm)), were compared between the groups with and without IPT. Changes in teardrop to lesser trochanter distance were measured to estimate changes in leg length and horizontal offset caused by THA. Logistic regression models were used to identify the risk factors for IPT. IPT was identified in 53 hips (3.3%).ResultsPatients with IPT had greater leg lengthening (12.3 versus 9.3 mm; P = .001) and higher prevalence of antero-inferior cup prominence (5.7 versus 0.4%; P = .002). There was no significant difference in inclination, anteversion, and horizontal offset change between the two groups. In multivariate analyses, greater leg lengthening, prominent acetabular cup, women, and higher body mass index were associated with IPT. All patients reported improvement in groin pain after arthroscopic tenotomy, while 35.7% with nonoperative management reported improvement (P < .001).ConclusionsSymptomatic IPT occurred in 53 (3.3%) of the 1,602 primary THAs. Our findings suggest that leg lengthening as well as prominent acetabular cup in THAs can be associated with the development of IPT. Arthroscopic tenotomy was effective in relieving groin pain caused by IPT.     

Does Prosthetic or Bony Impingement Occur More Often in Total Hip Arthroplasty: A Dynamic Preoperative Analysis

BackgroundImpingement is a leading cause for instability resulting in revision total hip arthroplasty (THA). Impingement can be prosthetic, bony, or soft tissue. The purpose of this study is to investigate, using a virtual simulation, whether bony or prosthetic impingement presents first in well-positioned THAs.MethodsTwenty-three patients requiring THA were planned for a ceramic-on-poly cementless construct using dynamic planning software. Cups were orientated at 45° inclination and 25° anteversion when standing. Femoral components and neck lengths were positioned to reproduce native anteversion and match contralateral leg length and offset. The type and location of impingement was then recorded with recreation of anterior and posterior impingement during standard and extreme ranges of motion (ROM).ResultsIn standard ROM, flexion produced both prosthetic and bony impingement and extension resulted in prosthetic impingement in models with lipped liners. In extreme ROM, anterior impingement was 78% bony in 32-mm articulations, and 88% bony in 36-mm articulations. Posterior impingement was 65% prosthetic in 32-mm articulations, and 55% prosthetic in 36-mm articulations. Dual mobility cups showed the greatest risk of posterior prosthetic impingement in hyperextension (74%).ConclusionIn standard ROM, both bony and prosthetic impingement occurred in flexion, while prosthetic impingement occurred in extension in models with lipped liners. In hyperextension, prosthetic impingement was more common than bony impingement, and was exclusively the cause of impingement when a lip was used. In flexion, impingement was primarily bony with the use of a 36-mm head. The risk of posterior prosthetic impingement was greatest with dual mobility cups.Level of Evidence3.