The Influence of Leg Length Discrepancy after Total Hip Arthroplasty on Function and Quality of Life: A Prospective Cohort Study

Gender differences in cementless short stem total hip arthroplasty: significantly higher femoral lengthening in female patients

Modern cementless short stems in total hip arthroplasty (THA) enable a precise reconstruction of the native pre-arthritic hip geometry. While gender differences have been reported for older generation straight hip stems, there are hardly reports regarding modern cementless short hip stems. Therefore, we aimed to evaluate the influence of gender differences in hip anatomy in cementless short stem THA. A total of 207 patients (109 females, 98 males) with unilateral THA and absence of contralateral joint space narrowing (Kellgren-Lawrence grade ≤ 2) were included. Acetabular height and offset as well as femoral height and offset were measured on pre- and 3-months-postoperative anteroposterior X-rays of the pelvis and compared to the contralateral hip. Additionally, implant position was evaluated on the postoperative radiograph. In male patients, the loss of acetabular offset was significantly greater than in females (p = 0.012), leading to a compensatory increase in femoral offset (p = 0.041). Femoral height discrepancy was significantly higher in females (p < 0.001), accounting for an increased global hip height discrepancy (p < 0.001). The mean acetabular anteversion was significantly greater in female patients (p < 0.001). Female patients are at higher risk of femoral lengthening in THA with a cementless short stem potentially caused by a further proximally conducted femoral neck osteotomy and show significantly higher cup anteversion angles. Therefore, surgeons should take special care to the level of neck resection and implant positioning in female patients.

The influence of prosthetic positioning and proximal femoral morphology on leg length discrepancy and early clinical outcomes of cementless total hip arthroplasty

BACKGROUND

Leg length discrepancy (LLD) is a common complication of total hip arthroplasty (THA). However, the relationship between femoral prosthesis filling, proximal femoral morphology, and acetabular prosthesis positioning with postoperative LLD and clinical outcomes is unclear. The aims of this study were to investigate the influence of canal flare index (CFI), canal fill ratio (CFR), center of rotation (COR), and femoral offset (FO) on (1) postoperative LLD; and (2) clinical outcomes in the two stem designs with different coating distribution.

METHODS

The study cohort included 161 patients who underwent primary cementless THA between January 2021 and March 2022 with either proximal coating or full coating stems. Multivariate logistic regression was used to assess the effect of CFI, CFR, COR, and FO on postoperative LLD, and linear regression to assess their effect on clinical outcomes.

RESULTS

No statistical difference was found in clinical outcomes or postoperative LLD between the two groups. High CFI (p = 0.014), low ΔVCOR (p = 0.012), and Gender (p = 0.028) were found independent risk factors for LLD one day postoperative. High CFI was also an independent risk factor for postoperative subjectively perceived LLD (p = 0.013). CFR at the level of 2 cm below the LT (p = 0.017) was an independent risk factor for Harris Hip Score.

CONCLUSIONS

Proximal femoral morphology and acetabular prosthesis positioning but not femoral prosthesis filling affected the LLD. High CFI was an independent risk factor for postoperative LLD and subjectively perceived LLD, and low ΔVCOR was also an independent risk factor for postoperative LLD. Women were susceptible to postoperative LLD.

Comparison of postoperative outcomes between bikini-incision via direct anterior approach and posterolateral approach in simultaneous bilateral total hip arthroplasty: a randomized controlled trial

The purpose of this study was to compare an oblique bikini-incision via direct anterior approach (BI-DAA) to a conventional posterolateral approach (PLA) during simultaneous bilateral total hip arthroplasty (simBTHA) in terms of early patient outcomes, postoperative functional recovery, and complications. From January 2017 to January 2020, 106 patients receiving simBTHA were enrolled and randomly allocated to the BI-DAA or PLA group. Primary outcomes were measured using hemoglobin (HGB) drop, transfusion rate, the length of stay (LOS), the visual analog scale (VAS) for pain, the Harris hip score, Western Ontario and McMaster Universities Osteoarthritis Index, and the scar cosmesis assessment and rating scale. Secondary outcomes were the operative time, radiographic measurements, including femoral offset, femoral anteversion, stem varus/valgus angle, and leg length discrepancy (LLD). The occurrence of postoperative complications was also recorded. There were no differences in demographic or clinical characteristics before surgery. Compared to the PLA, the patients in the BI-DAA group had lower HGB drop (24.7 ± 13.3 g/L vs. 34.7 ± 16.7, P < .01) and transfusion rates (9/50 vs. 18/50, P = .04) and a shorter LOS (5.12 ± 1.5 vs. 6.40 ± 2.0 days, P < .01) without increasing the operative time (169.7 ± 17.3 vs. 167.5 ± 21.8 min, P = .58). The BI-DAA group yielded a smaller LLD (2.1 ± 2.3 vs. 3.8 ± 3.0 mm, P < .01) and less variability in component orientation than the PLA group (100% vs. 93%, P = .01). As for the scar, the BI-DAA group produced a shorter incision length (9.7 ± 1.6 vs. 10.8 ± 2.0 mm, P < .01) and higher postoperative recovery satisfaction than the PLA group. Furthermore, the BI-DAA group had a reduced VAS score one week after surgery and had better functional recovery in three months postoperatively. The BI-DAA group had a higher incidence of LFCN dysesthesia (12/100 vs. 0/100 thighs, P < .01), while other complications did not differ significantly between the two groups. For simBTHA, the bikini incision offers early recovery, less variance in components orientation, better postoperative outcomes, and scar healing than the PLA. Therefore, the bikini incision could be a safe and feasible option for simBTHA recipients.

Assessing Leg Length and Offset in Anterior Total Hip Arthroplasty: Overlay Versus AP Pelvis Intraoperative Radiographic Techniques: A Retrospective Cohort Study

INTRODUCTION

Two intraoperative radiographic techniques to determine leg length and offset during anterior total hip arthroplasty (THA) are the AP pelvis and overlay techniques. The AP pelvis method measures LLDs and offset using AP fluoroscopic images, whereas the overlay method uses printed images of the native and replaced hips. The purpose of this study was to compare these techniques regarding clinical and radiographic LLD and offset discrepancies.

METHODS

Patients of a single surgeon at two hospitals from September 2017 to January 2021 were retrospectively reviewed. Clinically detectable LLD was recorded. Radiographic measurements were obtained from preoperative and postoperative radiographs. LLD was determined based on the vertical distance between the lesser trochanters and the ischial tuberosities. Total offset was measured using a combination of femoral and medial offset. The Student t-test, Fisher exact test, and Wilcoxon rank sum tests were used for statistical analysis.

RESULTS

Seventy-one procedures were done using the overlay technique and 61 used for the AP pelvis technique. No significant differences were observed in mean postoperative LLD (2.66 versus 2.88 mm, P = 0.66) and mean postoperative offset discrepancy (5.37 versus 4.21 mm, P = 0.143) between the overlay versus AP pelvis groups. The mean preoperative to postoperative absolute difference in offset was less than 5 mm in both groups. Clinically detectable LLD was noted in six of 71 patients in the overlay group and one of 61 in the AP pelvis group (P = 0.123).

CONCLUSION

No notable differences were observed in intraoperative leg length and offset discrepancies during direct anterior THA between the AP pelvis and overlay techniques, suggesting they are equally effective in determining LLD and offset intraoperatively. The choice of technique to use anterior THA should be based primarily on the surgeon's preference, comfort, and available resources.

The effectiveness and influencing factors of the "Y" line technique in reducing the leg length discrepancy after total hip arthroplasty

Objective

To introduce a surgical technique (the "Y" line technique) that will control leg length discrepancy (LLD) after total hip arthroplasty and to observe its effectiveness and influencing factors.

Methods

According to the inclusion and exclusion criteria, a total of 350 patients were selected in this study; 134 patients in whom used the "Y" line technique was used to control lower limb length were included in Group A and 166 patients treated with freehand methods to control lower limb length were included in Group B. A total of 50 patients in whom the standard anteroposterior x-ray of bilateral hips was taken preoperatively and in whom the "Y" line technique was used during the operation were included in Group C.

Results

The postoperative LLD of Group A was 4.74 mm (3.93), that of Group B was 5.85 mm (4.60), and that of Group C was 2 mm (1.00)-the difference was statistically significant (p < 0.001). There were significant statistical differences when comparisons were made between any two groups (p < 0.01). The distribution of postoperative LLD in Group A was better than that in Group B, and this factor was better in Group C than in Group A-the difference was statistically significant (p < 0.001). Severe unequal length rates of the lower extremities (LLD > 10 mm) were 5.97% (8/134) in Group A, 14.3% (24/166) in Group B, and 0% (0/50) in Group C-the difference was statistically significant (p < 0.001). There were significant differences between Group A and Group B and between Group B and Group C (p < 0.05), but there was no significant difference between Group A and Group C (p = 0.078).

Conclusion

The "Y" line technique, which does not increase the operating time and patient cost, can effectively reduce postoperative LLD. Insufficient internal rotation of the healthy lower extremity and the low projection position in the preoperative anteroposterior x-ray of the bilateral hips were important factors affecting the accuracy of the "Y" line technique.

A smaller femoral stem is needed for asian females

BACKGROUND

Current femoral implants are manufactured based on Western anatomical structures and may be too large for smaller physiques, such as those of Asian females. This study reviewed the femoral stem size distribution used in a high-volume total hip arthroplasty (THA) practice and evaluated malalignment in patients receiving a size one implant.

MATERIALS AND METHODS

A consecutive cohort of female patients self-reported as Asian (257 patients, 331 hips) or Caucasian (158 patients and 190 hips) were retrospectively evaluated. A single femoral stem type was used in all cases, performed by a single surgeon. Global hip offset (GHO) and leg length difference (LLD) were measured before and 6 weeks following THA. Differences between races were evaluated through Mann-Whitney U tests and chi-squared tests for continuous and categorical variables, respectively.

RESULTS

The proportion of size one implants was higher amongst Asian patients (20.5%) than Caucasian patients (2.6%) (p < 0.001). A LLD greater than 6 mm was noted in 24.6% of size one patients and 11.4% of all other sizes (p = 0.010). Varus malalignment occurred in 47.9% of size one patients and 22.1% of all other sizes (p < 0.001). No fractures occurred in size one patients, and nine fractures (one intraoperative and eight post-operative) occurred in all other sizes (p = 0.258).

CONCLUSION

The high proportion of size one stems required in Asian females and the higher incidence of LLD > 6 mm and varus malalignment suggest a distinct need for smaller femoral implants, especially for Asian females.

Supine versus lateral position for total hip replacement: accuracy of biomechanical reconstruction

BACKGROUND

Restoration of normal hip anatomy and biomechanics is a key surgical goal for success in total hip arthroplasty. The aim of this study was to evaluate the influence, if any, that patient positioning in the supine and lateral decubitus positions has in achieving this goal.

MATERIALS AND METHODS

A single center multi-surgeon case-matched series from a tertiary level referral center of patients undergoing primary unilateral THA for osteoarthritis between April 2018 and December 2019 was retrospectively analyzed. Patients (n = 200) were divided into two matched groups: supine (anterior approach, n = 100) and lateral decubitus (direct lateral or posterior/SuperPATH™ approaches, n = 100). Post-operative anteroposterior pelvic radiographs were analyzed using a previously validated software (SurgiMap, Nemaris Inc., USA) for parameters of reconstruction of the hip in the coronal plane; leg length discrepancy, vertical and horizontal displacement of the center of rotation, femoral offset, and total offset.

RESULTS

Mean absolute leg length discrepancy in the supine group was 0.6 ± 3.3 mm (95% [CI] - 0.1 to 1.2 mm) versus 2.4 ± 3.8 mm (95% [CI] 1.6 to 3.1) in the lateral decubitus position (p < 0.001). The center of rotation was displaced medially by a mean of 3.2 ± 2.7 mm in the supine group versus 1.3 ± 4.0 mm in the lateral decubitus group (p < 0.001). For a surgical target of reconstructing both leg length and total offset within 5 mm of native anatomy, the supine group was more than twice as likely to achieve these goals with fewer outliers (OR 2.631, 95% [CI] 1.901-3.643) (76% v 30%, p < 0.001).

CONCLUSION

Total hip arthroplasty through the anterior approach in the supine position is more consistent and accurate for the restoration of leg length and total offset. Further study is required to assess how this translates with outcome.

LEVEL OF EVIDENCE

III-retrospective cohort study.

The intraoperative hip range of motion in total hip arthroplasty predicts postoperative patient's satisfaction for cutting toenails and putting on sock

BACKGROUND

Restricted hip range of motion (ROM) has been proposed as a useful diagnostic tool for osteoarthritis. The relations between the intraoperative hip ROM under anesthesia in total hip arthroplasty (THA) and recovery of clinical mobility outcomes were unclear. This study evaluated the association between the intraoperative hip ROM under anesthesia in THA and the postoperative recovery of clinical mobility, including cutting toenails and putting on socks after THA.

METHODS

The study was performed as a prospective cohort study and included 93 hips in 85 patients who underwent primary anterior-based muscle-sparing THA in the supine position. The hip ROM was evaluated under anesthesia before skin incision and intraoperative stability test. The Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire (JHEQ) was evaluated. A questionnaire on whether and how patients could cut toenails and putting on socks was assessed. The relationship between hip ROM at intraoperative stability tests and JHEQ moving score, cutting toenails, and putting on socks scores were evaluated statistically.

RESULTS

We observed a week positive correlation between intraoperative hip ROM and the total of JHEQ mobility score. A moderate positive correlation was observed between external rotation angle with flexion 90°and cutting toenails and putting on socks score oh JHEQ. 94.6% and 96.8% of the patients could cut their toenails and putting on socks by themselves after surgery. The optimum cutoff range for high patient satisfaction for putting on socks and cutting toenails was 110° for flexion and 35°-40° for the external rotation angle in the intraoperative stability test.

CONCLUSION

Hip ROM during intraoperative stability testing, especially the external rotation angle can predict postoperative outcomes and patient satisfaction for cutting toenails and putting on socks. We suggested that the capsule or capsular ligament release around the hip was increased to provide sufficient ROM without compromising stability.

Influence of implantation of a total hip endoprosthesis on the ipsilateral leg alignment: the effect of sex and dysplasia of the hip

INTRODUCTION

Differences in leg and hip morphology exist between sexes and developmental hip dysplasia is known to alter proximal femoral morphology. The purpose of this study was to determine whether existing differences in leg alignment due to sex or developmental hip dysplasia have an effect on changes in leg alignment after total hip arthroplasty.

MATERIALS AND METHODS

30 hip osteoarthritis patients underwent biplanar full-length radiography in the standing position preoperatively and 3 months after total hip arthroplasty. Differences in leg alignment between men and women and between patients with primary hip osteoarthritis and patients with developmental dysplasia before and after surgery were tested using a general linear model for repeated measures.

RESULTS

Implantation of a hip prosthesis had no differential effect on ipsilateral leg alignment in patients with hip osteoarthritis due to dysplasia and in patients with primary hip osteoarthritis. However, patients with hip osteoarthritis due to dysplasia had a 2.1° higher valgus both before and after surgery. After total hip arthroplasty, women had a significantly greater increase in varus angle (1.6° vs. 0°) and femoral offset (10.5 vs. 4.6 mm) compared with men. Because the change in acetabular offset was smaller (2.2 vs. 6.2 mm), the global femoral offset was only increased in women. Femoral torsion was constant for men (15.0° and 16.5°), whereas femoral torsion was significantly reduced in women (19.9° and 13.2°).

CONCLUSIONS

Hip arthroplasty has a greater effect on leg axis in women than in men. The axial leg alignment of women could change from a natural valgus to a varus alignment. Therefore, surgeons should consider the effects of total hip arthroplasty on leg alignment in patients with hip osteoarthritis. Whether these changes in leg alignment are also clinically relevant and lead to premature medial or lateral knee osteoarthritis should be investigated in future work.

TRIAL REGISTRATION

This study was registered with DRKS (German Clinical Trials Register) under the number DRKS00015053. Registered 1st of August 2018.

Characterizing the Magnitude of and Risk Factors for Functional Limb Lengthening in Patients Undergoing Primary Total Knee Arthroplasty

Background: There is little data on the magnitude and factors for functional leg lengthening after primary total knee arthroplasty (TKA). Questions/Purpose: We sought to determine the incidence of and risk factors for functional leg lengthening after primary TKA. Methods: We retrospectively reviewed consecutive unilateral primary TKAs at a single institution from 2015 to 2018. Of the 782 TKAs included, 430 (55%) were performed in women; the mean age was 66 years, and the mean body mass index was 29 kg/m². Preoperatively, 541 (69%) knees were varus deformities and 223 (29%) were valgus deformities. Hip to ankle biplanar radiographs were obtained preoperatively and 6 weeks postoperatively for all patients. Two independent researchers measured leg length, coronal plane deformity, lateral knee flexion angle, and overall mechanical alignment on all preoperative and postoperative radiographs. Results: The mean overall ipsilateral functional leg lengthening was 7.0 mm. Seven hundred knees (90%) were overall functionally lengthened, including 462 (59%) knees lengthened >5 mm and 250 (31%) knees lengthened 10 mm or more. A valgus deformity and coronal plane deformity of 10° or more were significant risk factors for increased functional lengthening. Patients with severe valgus deformities (>10°) had the largest amount of functional lengthening, at a mean of 13.5 mm. Conclusion: After primary TKA, 90% of limbs are functionally lengthened, including roughly one-third over a centimeter. Valgus knee deformities and severe deformities (>10°) were significant risk factors for increased limb lengthening.

Utility of Intraoperative Fluoroscopic Positioning of Total Hip Arthroplasty Components Using a Posterior and Direct Anterior Approach

INTRODUCTION

Positioning of implant components for total hip arthroplasty (THA) is important for polyethylene liner wear, prosthesis joint stability, and range of motion. The introduction of fluoroscopy for the direct anterior approach has been shown to improve physician accuracy for component positioning. Few studies compare the use of intraoperative fluoroscopy for THA component positioning in posterior THA. The purpose of this project is to retrospectively evaluate the effect of intraoperative fluoroscopy on component positioning for THA using posterior and direct anterior approach (DAA).

MATERIALS AND METHODS

A retrospective review of postoperative weight-bearing X-ray films of THAs was performed over a 2-year period where a single fellowship-trained total joint surgeon introduced direct anterior approach into his practice while expanding the intraoperative use of fluoroscopy for all THA procedures, regardless of approach. Component position was evaluated through radiographic measurement of acetabular cup inclination (goal of 40 degrees), limb length discrepancy (goal of 0 mm), and femoral component offset difference (goal of 0 mm). Radiographic analysis was performed by two independent providers. Statistical analysis was performed using Student's t-tests.

RESULTS

A total of 107 patients with an average age of 62 years were identified during the 2-year period surrounding the THA practice change, adding fluoroscopy to posterior and DAA THA. Three cohorts were identified: cohort A: 44 patients who underwent posterior THAs without the use of intraoperative fluoroscopy, cohort B: 35 patients who underwent direct anterior approach THAs with the use of intraoperative fluoroscopy, and cohort C: 18 patients who underwent posterior THAs with the use of intraoperative fluoroscopy. The use of intraoperative fluoroscopy for the posterior approach versus unguided posterior approach increased accuracy of both cup inclination (44 degrees vs 50 degrees, P < .05) and femoral offset (4 mm vs 7 mm, P < .05). A comparison of DAA with fluoroscopy versus posterior approach without fluoroscopy showed improvement in cup inclination (48 degrees vs 50 degrees, P < .05). Fluoroscopy with posterior approach versus fluoroscopy with DAA was found to have improved cup inclination (44 degrees vs 48 degrees, P < .05).

CONCLUSION

Intraoperative use of fluoroscopy can improve component positioning for posterior THA.

Effectiveness of an accelerometer-based portable navigation for intraoperative adjustment of leg length discrepancy in total hip arthroplasty in the supine position

BACKGROUND

This study aimed to examine the accuracy of the HipAlign® accelerometer-based portable navigation system by measuring the intraoperative leg length change of patients who underwent total hip arthroplasty (THA) and comparing the measured leg length discrepancy (LLD) determined by the navigation system and a freehand technique.

METHODS

A total of 61 patients who underwent THA using the anterolateral approach in the supine position were included in this study and divided into two groups: those who underwent THA with navigation (Group N; N = 31) and with the freehand technique (Group F; N = 30). Statistical analyses were performed to compare the intraoperative leg length change, pre- and post-LLD, absolute values of post-LLD, and the number of patients with the postoperative LLD within 10 mm and 5 mm between the two groups. Additionally, we examined the correlation between the leg length change obtained through intraoperative navigation and measured from the radiographs. Moreover, to evaluate the navigation accuracy, we examined the correlation between the absolute error of leg length change and cup orientation.

RESULTS

The postoperative LLD was significantly lower and the number of patients with the postoperative LLD within 5 mm was significantly higher in Group N, compared with Group F. Additionally, the amount of leg length change measured intraoperatively by the navigation system was strongly correlated with the values obtained by the postoperative radiographic measurement with a small absolute error and minimal wasted time. Moreover, a significant positive correlation was found between the absolute error of the leg length change and that of the cup inclination.

CONCLUSIONS

Our study demonstrates that the accelerometer-based portable navigation system is useful for the intraoperative adjustment of leg length discrepancy during THA for patients in the supine position, as it provides good accuracy and minimizes required time for use.

[Artificial intelligence assisted total hip arthroplasty for patients with Crowe type developmental dysplasia of the hip]

Objective

To investigate the early effectiveness of artificial intelligence (AI) assisted total hip arthroplasty (THA) system (AIHIP) in the treatment of patients with Crowe type Ⅳ developmental dysplasia of the hip (DDH).

Methods

The clinical data of 23 patients with Crowe type Ⅳ DDH who met the selection criteria between May 2019 and December 2020 were retrospectively analyzed. There were 3 males and 20 females, the age ranged from 44 to 74 years, with an average of 52.65 years. The absolute value of the lower limbs discrepancy before operation was (15.17±22.17) mm. The preoperative Harris score was 62.4±7.2. The AIHIP system was used for preoperative planning, and the operations were all performed via conventional posterolateral approach. Thirteen patients with difficulty in reduction during operation underwent subtrochanteric shortening osteotomy (SSOT). The operation time, hospital stay, and adverse events were recorded; Harris score was used to evaluate the function of the affected limb at 1 day before operation and 1 week and 6 months after operation; pelvic anteroposterior X-ray film was taken at 1 day after operation to evaluate the position of the prosthesis. The matching degree of prosthesis was evaluated according to the consistency of intraoperative prosthesis model and preoperative planning.

Results

The matching degree of acetabular cup model after operation was 16 cases of perfect matching, 4 cases of general matching (1 case of +1, 3 cases of -1), and 3 cases of mismatch (all of them were +2), the coincidence rate was 86.96%. The matching degree of femoral stem model was perfect matching in 22 cases and general matching in 1 case of -1, and the coincidence rate was 100%. One patient had a periprosthesis fracture during operation, and was fixed with a wire cable during operation, and walked with the assistance of walking aid at 6 weeks after operation; the rest of the patients walked with the assistance of walking aid at 1 day after operation. The operation time was 185-315 minutes, with an average of 239.43 minutes; the hospital stay was 8-20 days, with an average of 9.96 days; and the time of disengagement from the walking aid was 2-56 days, with an average of 5.09 days. All patients were followed up 6 months. All incisions healed by first intension, and there was no complication such as infection, dislocation, refracture, and lower extremity deep venous thrombosis; X-ray films at 1 day and 6 months after operation showed that the acetabular and femoral prostheses were firmly fixed and within the safe zone; the absolute value of lower limbs discrepancy at 1 day after operation was (11.96±13.48) mm, which was not significantly decreased compared with that before operation ( t=0.582, P=0.564). All osteotomies healed at 6 months after operation. The Harris scores at 1 week and 6 months after operation were 69.5±4.9 and 79.2±5.7 respectively, showing significant differences between pre- and post-operation ( P<0.05). At 6 months after operation, the hip function was evaluated according to Harris score, and 13 cases were good, 9 cases were fair, and 1 case was poor.

Conclusion

AIHIP system-assisted THA (difficult to reposition patients combined with SSOT) for adult Crowe type Ⅳ DDH has high preoperative planning accuracy, easy intraoperative reduction, early postoperative landing, and satisfactory short-term effectiveness.

Are We Being Fooled by Fluoroscopy? Distortion May Affect Limb-Length Measurements in Direct Anterior Total Hip Arthroplasty

BACKGROUND

Distortion is an intrinsic phenomenon associated with image-intensified fluoroscopy that is both poorly understood and infrequently appreciated by orthopedic surgeons. Little information exists regarding its potential influence on intraoperative parameters during orthopedic surgery, let alone during direct anterior (DA) total hip arthroplasty (THA). The purpose of this study was to quantify the amount of potential error caused by fluoroscopic distortion during DA THA.

METHODS

Intra-operative fluoroscopic pelvic images from 74 DA THAs were reviewed by two independent readers. All images were obtained using the same fluoroscopic C-arm unit with a radiopaque grid attached to the image intensifier. The vertical distortion from a straight central horizontal line at the peripheries of images were measured and summed to yield the combined vertical distortion similar to how a surgeon calculates a side to side comparison of limb lengths. Simple linear regression was used to evaluate associations between total distortion and patient demographics, operating theaters, and various operative parameters.

RESULTS

The average combined distortion was 10.0mm (range 2.0-20.0mm). There was a significant difference in the average distortion observed in different theaters (P < .001). There was no association between distortion and patient demographics or fluoroscopic time (all, P > .05).

CONCLUSION

Fluoroscopic distortion is unpredictable and can cause a substantial amount of error when comparing limb lengths during DA THA. This is a critical finding as this amount of inaccuracy could lead to unintended implant positioning and limb-length discrepancies if unaccounted for.

Symptomatic leg length discrepancy after total hip arthroplasty is associated with new onset of lower back pain

BACKGROUND

Leg length discrepancy (LLD) is common after total hip arthroplasty (THA) with a plethora of clinical consequences. The associations between symptomatic (sLLD; disturbing perception of anatomical leg length discrepancy), anatomical (aLLD; side difference in leg length between the center of rotation of the hip and the center of the ankle joint) and intraarticular (iLLD; side difference between the tear drop figure and the most prominent point of the trochanter minor) LLD and lower back have not yet been reported in the literature. We performed a retrospective study to answer if postoperative (1) symptomatic LLD, (2) anatomic LLD, and (3) a change in intraarticular leg length are associated with lower back pain in patients undergoing THA. Further, we aimed to answer (4) whether symptomatic LLD is associated with the magnitude of anatomical LLD and the change in intraarticular leg length.

HYPOTHESIS

LLD after THA is associated with lower back pain.

MATERIALS AND METHODS

Seventy-nine consecutive patients were retrospectively analyzed for the presence of aLLD and iLLD using EOS™ and X-rays, and were interviewed for the presence of sLLD and lower back pain using a questionnaire 5 years after primary THA.

RESULTS

Postoperative new onset of lower back pain was reported by 9 (11%) patients. Twenty (25%) patients reported sLLD. Anatomical LLD>5mm was present in 44 (56%) (median 8.0 (IQR -3.0 to 12.0; range -22 to 22) mm) and>10mm in 17 (22%) (median 12.0 (IQR 11.0 to 16.5; range -22 to 22) mm) patients. iLLD changed>5mm in 44 (56%) (median 8.5 (IQR 7.0 to 10.0; range -8 to 18) mm) and>10mm in 10 (13%) (median 14.0 (IQR 12.5 to 14.5; range 11 to 18) mm). New onset lower back pain was associated with sLLD (p=0.002) but not with aLLD or iLLD. Patients without preoperative lower back pain had a statistically significant association between presence of sLLD and an aLLD of >10mm (p=0.01).

CONCLUSIONS

Symptomatic LLD after primary THA is associated with postoperative new onset of lower back pain irrespective of the magnitude of LLD. In patients without lower back pain prior to THA, symptomatic LLD is associated with anatomical LLD of more than 10mm.

LEVEL OF EVIDENCE

IV.

Factors associated with health-related quality of life in Japanese patients with hip osteoarthritis: A cross-sectional study

Background/Purpose:

Chronic symptoms related with hip osteoarthritis (OA) can negatively affect health-related quality of life (HRQoL). The purpose of this study was to examine factors related to a HRQoL measure that considers an Asian lifestyle in Japanese patients with hip OA.

Methods:

Forty-seven female subjects participated. The dependent variable was the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ), which assessed HRQoL. Potential factors were measured as independent variables. After screening, potential variables were entered into a multiple regression analysis to determine which variables were related to HRQoL.

Results:

In the regression model, knee extension muscle strength on the unaffected side and hip flexion range of motion (ROM) on the affected side were associated with HRQoL. Higher strength and higher ROM were related to greater HRQoL.

Conclusion:

Results can help health-care providers develop appropriate rehabilitation programs for improving HRQoL in patients with hip OA.

Discrepancy of Trial Rasp and Femoral Stem Relative Position Within the Femoral Canal of a Coated Tapered System: An Intraoperative, Intrapatient Controlled Study

Background

For a successful total hip arthroplasty, the final position of the trial rasp should be adopted by the femoral stem to achieve correct positioning. This study aimed to characterize the discrepancy of the stem and rasp position in vivo of a widely used dual-tapered straight stem with rectangular cross section that is known to have an oversized stem with respect to the rasp.

Methods

The distances between the tip of the greater trochanter and the shoulder of the implant and rasp were measured on 39 intraoperatively acquired fluoroscopic image pairs. Leg-length discrepancy was also measured clinically before and after surgery.

Results

A paired t-test showed a significant average protrusion of the femoral stem with respect to the final rasp position of 2.63 mm (standard deviation = 2.3 mm, P < .001), while 88% of the cases had no leg-length discrepancy after surgery. The quantified stem protrusion was statistically significant but did not reach clinical relevance and was easily mitigated in our study.

Conclusions

The quantified stem protrusion appears to be clinically manageable, as only 2 cases required attenuation of stem positioning: in one case by the use of a femoral head with a shorter neck and in the other case by rerasping the femoral bed. Neither case was associated with the most extreme differences in position of the stem with respect to the final rasp. In addition, the used stem shows good overall outcomes in other studies. It appears that factors other than stem and rasp position play a critical role to the surgeon and for total hip arthroplasty success.

The Delta of Correction: a novel, more reliable variable than limb-length discrepancy at predicting outcome after total hip arthroplasty

BACKGROUND

Leg-length discrepancy (LLD) is a frequent and recurring issue after total hip arthroplasty (THA). It can lead to discomfort and litigation due to the patient's perception of this inequality.

PURPOSE

The aim of this study was to evaluate the functional impact of postoperative LLD and length correction in patients after primary THA. We hypothesised that clinical outcomes are inversely correlated to length correction and residual discrepancy.

METHODS

In a prospective cohort, we included 121 patients undergoing unilateral primary THA. Patients were categorised into 3 groups based on their residual LLD using routine EOS imaging; Shorter (<-5 mm); Equal (-5 mm to +5 mm); and Longer (>+5 mm). Delta of Correction (DC) was defined as the difference between pre- and postoperative discrepancy measured on EOS imaging. Functional scores (HHS, Postel Merle d'Aubigné, and WOMAC) were measured preoperatively and at last follow-up. The average follow-up was 24 months. We evaluated the clinical and radiographic outcomes regarding the residual LLD and DC.

RESULTS

All patients had improvement in their functional scores at last follow-up. There was no difference in clinical outcomes, regardless of preoperative or residual LLD. The highest scores were found in the population with the smallest variations (DC -5 to +5 mm, HHS 96). Conversely, poorer results were found in shortened patients (DC <-5 mm), HHS 86, and lengthened patients, corrected by > 15 mm, with HHS of 83, p < 0.005. Patient perception of postoperative LLD correlated with the DC (p = 0.004).

CONCLUSION

The DC measurement is a more effective assessment than arthroplasty.

Greater increase in femoral offset with use of collum femoris-preserving stem than Tri-Lock stem in primary total hip arthroplasty

OBJECTIVE

This study was performed to compare the clinical outcomes and performance of the collum femoris-preserving (CFP) stem (Waldemar Link GmbH & Co., Hamburg, Germany) and the Tri-Lock stem (DePuy Orthopaedics, Warsaw, IN, USA) in terms of femoral offset (FO) and leg length reconstruction.

METHODS

Clinical and radiographic data of patients who underwent total hip arthroplasty with either a CFP stem or Tri-Lock stem from January 2016 to March 2017 were compared (65 and 57 patients, respectively). The Harris hip score and Western Ontario and McMaster Universities Osteoarthritis Index were recorded. The FO, femoral vertical offset, and neck-shaft angle were measured at the last follow-up. The occurrence of dislocation and periprosthetic fracture during the follow-up period was recorded.

RESULTS

The CFP stem induced significantly more FO than did the Tri-Lock stem on the operated side than contralateral side (3.63 ± 4.28 vs. 0.83 ± 5.46 mm). Significantly fewer patients had a >5-mm decrease in FO on the unaffected side in the CFP stem group (n = 1) than Tri-Lock stem group (n = 10).

CONCLUSION

Both stems similarly improved hip function and reconstructed the leg length, but the CFP stem was superior to the Tri-Lock stem in reconstructing FO.

Errors in femoral anteversion, femoral offset, and vertical offset following robot-assisted total hip arthroplasty

The objectives were to determine errors in femoral anteversion (FA), femoral offset (FO), and vertical offset (VO) with robot-assisted total hip arthroplasty (THA) and how consistently these errors are within clinically desirable limits of ±5° and ±5 mm. After preoperative planning, robot-assisted THAs were performed on twelve cadaveric specimens. The error between achieved and planned component placements was used to determine bias (mean error) and precision (SD of error). The percent of the population within clinically desirable limits was determined. Bias of 1.5° and 2.7 mm occurred for FA and VO, respectively. Precision was 1.2° for FA and better than 1.5 mm for FO and VO. The percent of population within clinically desirable limits was at least 95% for FA and at least 99% for FO. With limits of ±7 mm, at least 95% of the population was within these limits for VO. Robot-assisted THA may improve clinical outcomes.

Effect of placement of acetabular prosthesis on hip joint function after THA

The good recovery of hip function after THA depends on reconstruction of acetabular prosthesis accurately. So we investigated the effect of acetabular prosthesis placement on hip joint function after THA and analyzed the clinical data of 432 patients with unilateral THA retrospectively . The patients were followed-up to evaluate the Harris score and hip range of motion (ROM). The hip ROM, the Harris score and the good rate of Harris score were compared between different groups. Comparison of the good rate of Harris score showed that 85%∼100% group of the rotation center horizontal position ratio was higher than >100% group; 80%∼120% group of the rotation center vertical position ratio was higher than >160% group; and the 90%∼110% group and 110%∼130% group of femoral offset ratio were higher than 90% and >130% groups. Comparison of Harris score showed that 85%∼100% and 70%∼85% groups of rotation center horizontal position ratio were higher than 70% and >100% groups; 80%∼120% group of rotation center vertical position ratio was the highest; and 90%∼110% group and 110%∼130% group of femoral offset ratio were higher than >130% and 90% groups. Comparison of hip ROM showed that 85%∼100% and 70%∼85% groups of the rotation center horizontal position ratio were higher than 70% and >100% groups; 80%∼120% group of the rotation center vertical position ratio was the highest; and hip ROM from high to low are 90%∼110%, 110%∼130%, >130% and 90% groups of femoral offset ratio. These findings indicated that during the early follow-up period of THA, if the horizontal position of femoral head rotation center was reconstructed in 0.85 to 1 times of healthy side when compared with reconstruction >1 times of the healthy side and if the vertical position of femoral head rotation center was reconstructed in 0.8 to 1.2 times of the healthy side when compared with reconstruction in >1.6 times of the healthy side, better hip function recovery and optimal hip ROM were obtained. The optimal reconstruction range of femoral offset is 0.9 to 1.3 times of the healthy side.

Does body mass index affect restoration of femoral offset, leg length and cup positioning after total hip arthroplasty? A prospective cohort study

Background

In obese patients, total hip arthroplasty (THA) can be technically demanding with increased perioperative risks. The aim of this prospective cohort study is to evaluate the effect of body mass index (BMI) on radiological restoration of femoral offset (FO) and leg length as well as acetabular cup positioning.

Methods

In this prospective study, patients with unilateral primary osteoarthritis (OA) treated with THA between September 2010 and December 2013 were considered for inclusion. The perioperative plain radiographs were standardised and used to measure the preoperative degree of hip osteoarthritis, postoperative FO, leg length discrepancy (LLD), acetabular component inclination and anteversion.

Results

We included 213 patients (74.5% of those considered for inclusion) with a mean BMI of 27.7 (SD 4.5) in the final analysis. The postoperative FO was improper in 55% and the LLD in 15%, while the cup inclination and anteversion were improper in 13 and 23% of patients respectively. A multivariable logistic regression model identified BMI as the only factor that affected LLD. Increased BMI increased the risk of LLD (OR 1.14, 95% CI 1.04 to 1.25). No other factors included in the model affected any of the primary or secondary outcomes.

Conclusion

Increased BMI showed a negative effect on restoration of post-THA leg length but not on restoration of FO or positioning of the acetabular cup. Age, gender, OA duration or radiological severity and surgeon’s experience showed no relation to post-THA restoration of FO, leg length or cup positioning.

Are there clinically relevant anatomical differences of the proximal femur in patients with mild dysplastic and primary hip osteoarthritis? A CT-based matched-pairs cohort study

AIM

To investigate the three-dimensional anatomy and shape of the proximal femur, comparing patients with secondary osteoarthritis (OA) due to mild developmental dysplasia of the hip (DDH) and primary hip OA.

MATERIALS AND METHODS

This retrospective radiographic computed tomography (CT)-based study investigated proximal femoral anatomy in a consecutive series of 84 patients with secondary hip OA due to mild DDH (Crowe type I&II/Hartofilakidis A) compared to 84 patients with primary hip OA, matched for gender, age at surgery, and body mass index.

RESULTS

Men with DDH showed higher neck shaft angles (127±5° vs. 123±4°; p<0.001), whereas women with DDH had a larger femoral head diameter (46±4 vs. 44±3 mm; p=0.002), smaller femoral offset (36±5 vs. 40±4 mm; p<0.001), decreased leg torsion (25±13° vs. 31±16°; p=0.037), and a higher neck shaft angle (128±7° vs. 123±4°; p<0.001) compared to primary OA patients. Similar patterns of the three-dimensional endosteal canal shape of the proximal femur, but a high inter-individual variability for femoral canal torsion at the meta-diaphyseal level were found for DDH and primary OA patients.

CONCLUSION

Standard cementless stem designs are suitable to treat patients with secondary hip OA due to mild DDH; however, high patient variability and subtle anatomical differences in the proximal femur should be respected.

The association of leg length and offset reconstruction after total hip arthroplasty with clinical outcomes

BACKGROUND

Restoring native hip anatomy and biomechanics is important to create a well-functioning hip arthroplasty. This study investigated the association of hip offset and leg length after hip arthroplasty with clinical outcomes, including patient reported outcome measures, the Trendelenburg Test and gait analysis.

METHODS

In 77 patients undergoing primary hip arthroplasty for osteoarthritis (age mean = 65 SD = 11 years; BMI mean = 27 SD = 5 kg/m²), hip offset and leg length discrepancy were measured on anteroposterior radiographs. The Western Ontario & McMaster Universities Osteoarthritis Index, the Trendelenburg Test and gait were assessed preoperatively, and at 3 and 12 months postoperatively. An inertial measurement unit was used to derive biomechanical parameters, including spatiotemporal gait parameters and tilt angles of the pelvis. Relationships between radiographic and functional outcomes were investigated, and subgroups of patients with >15% decreased and increased femoral offset were analysed separately.

FINDINGS

Patient-reported function scores and clinical tests demonstrated a few significant, weak correlations with radiographic outcomes (Spearman's ρ range = 0.26-0.32; p < 0.05). Undercorrection of femoral offset was associated with lower patient-reported function scores and with more step irregularity as well as step asymmetry during gait. Postoperative leg length inequality was associated with increased frontal plane tilt angle of the pelvis during the Trendelenburg Test and increased sagittal plane motion of the pelvis during gait. Femoral offset subgroups demonstrated no significant differences for patient-reported function scores and outcomes of the Trendelenburg Test and gait analysis.

INTERPRETATION

Reduced hip offset and leg length discrepancy following hip arthroplasty seem to be marginally associated with worse clinical outcomes.

Increased Persistent Mid-Thigh Pain After Short-Stem Compared With Wedge-Shaped Straight-Stem Uncemented Total Hip Arthroplasty at Medium-Term Follow-Up: A Randomized Double-Blinded Cross-Sectional Study

BACKGROUND

Femoral prosthesis design may impact the frequency of mid-thigh pain. We compared current, incidental, and persistent mid-thigh pain between the short-stem, Collum Femoris femur prosthesis, and the wedge shaped straight-stem, Zweymüller femur prosthesis and studied the associations between demographics, radiographic measurements, and mid-thigh pain.

METHODS

We contacted patients from a randomized controlled trial who underwent uncemented total hip arthroplasty (THA) for hip osteoarthritis at a mean follow-up of 44 months (range 24-64 months). Patients were specifically assessed for current (during assessment), incidental (any time postoperatively for >1 week) mid-thigh pain, and persistent (any time postoperatively for >2 years) mid-thigh pain. Furthermore, we used regression analysis to study associations between demographics, radiographic measurements, and mid-thigh pain.

RESULTS

One hundred forty of 150 patients (93%) responded to our assessment. Mean age at the time of operation was 62 years (±7.0). Current mid-thigh pain occurred in 16 patients (23%) in the Collum Femoris Preserving (CFP) group compared with 10 patients (14%) in the Zweymüller group (P = .192). Incidental mid-thigh pain occurred in 24 patients (34%) in the CFP group compared with 15 patients (21%) in the Zweymüller group (P = .090). Persistent mid-thigh pain was found in 13 patients (19%) in the CFP group compared with five patients (7%) in the Zweymüller group (P = .043). Varus malalignment (odds ratio 1.819 [95% confidence interval 1.034-3.200]) and leg lengthening (odds ratio 1.107 per cm lengthening [95% confidence interval 1.026-1.195]) showed significant associations with mid-thigh pain.

CONCLUSIONS

We found more persistent mid-thigh pain after short-stem uncemented THA compared to wedge-shaped straight-stem uncemented THA during medium-term follow-up. Varus malalignment and leg lengthening were associated with mid-thigh pain.

Effect of leg-length discrepancy following total hip arthroplasty on collapse of the contralateral hip in bilateral non-traumatic osteonecrosis of the femoral head

AIMS

The purpose of this study was to examine whether leg-length discrepancy (LLD) following unilateral total hip arthroplasty (THA) affects the incidence of contralateral head collapse and subsequent THA in patients with bilateral osteonecrosis, and to determine factors associated with subsequent collapse.

PATIENTS AND METHODS

We identified 121 patients with bilateral non-traumatic osteonecrosis who underwent THA between 2003 and 2011 to treat a symptomatic hip, and who also exhibited medium-to-large lesions (necrotic area ≥ 30%) in an otherwise asymptomatic non-operated hip. Of the 121 patients, 71 were male (59%) and 50 were female (41%), with a mean age of 51 years (19 to 71) at the time of initial THA. All patients were followed for at least five years and were assessed according to the presence of a LLD (non-LLD vs LLD group), as well as the LLD type (longer non-operated side vs shorter non-operated side group).

RESULTS

Overall, 68 hips (56%) became painful and progressed to collapse at a mean of 2.6 years (0.2 to 13.8), resulting in 59 THAs (49%). The five-year collapse-free survival rate for the non-LLD group was 59% (95% confidence interval (CI) 46.8 to 71.8) compared with 45% (95% CI 32.9 to 57.5) for the LLD group (p = 0.036), and 66% (95% CI 55.2 to 77.2) for the longer non-operated side group compared with 32% (95% CI 19.1 to 44.9) for the shorter non-operated side group (p < 0.001). Multivariate regression analyses found that large lesions had a higher risk of collapse than medium-size lesions (odds ratio (OR) 4.19, 95% confidence interval (CI) 1.69 to 10.38; p = 0.002). Meanwhile, patients with a LLD < 3 mm (OR 0.20, 95% CI 0.08 to 0.52; p = 0.001) or a longer non-operated leg (OR 0.11, 95% CI 0.04 to 0.28; p < 0.001) after THA were less likely to experience a subsequent collapse.

CONCLUSION

We found that LLD may be a modifiable risk factor for femoral head collapse. Minimizing LLD and particularly avoiding a shorter non-operated limb after THA may lead to a lower risk of collapse of the asymptomatic hip in patients with bilateral non-traumatic osteonecrosis. Cite this article: Bone Joint J 2019;101-B:303-310.

Patient-dependent risk factors for self-perceived leg length discrepancy after total hip arthroplasty

PURPOSE

Patients with equal objective leg length discrepancy (LLD) may have different subjective perceptions of this condition. Our aim was to analyze the effects of gender, age, operated side, surgical approach, body height, body mass index (BMI) and LLD measurements on self-perceived LLD after total hip arthroplasty (THA).

MATERIALS AND METHODS

Observational cohort study with minimum 5-year follow-up included 159 patients with unilateral primary THA at a single institution, who reported subjective feeling of equal or unequal leg lengths after THA. Gender, age, body height, BMI, surgical approach, preoperative and postoperative absolute/relative/pelvic radiographic LLD measurements were included in direct comparison between groups and multivariate analyses with self-perceived LLD as the outcome variable.

RESULTS

Out of 159 participants, 39% subjectively perceived postoperative LLD, while others reported equal leg lengths. The two groups postoperatively differed in the median relative LLD (10 mm vs. 5 mm; p = 0.01) and WOMAC (230 mm vs. 110 mm; p < 0.01), but not in the pelvic radiographic LLD. After adjustment for gender, age, operated side and surgical approach, postoperative relative LLD (odds ratio 1.38 for each 5 mm increment; 95% CI 1.01-1.74) and combination of BMI < 26 kg/m² and body height < 1.75 m (odds ratio 2.49; 95% CI 1.14-5.41) were independent risk factors for self-perceived LLD.

CONCLUSIONS

Clinical relative LLD measurements are better predictors of self-perceived postoperative LLD than pelvic radiographic measurements. Patients with smaller body dimensions will more likely report subjective leg length inequality at a given objective LLD, regardless of gender or age.

The external obturator footprint as a landmark in total hip arthroplasty through a direct anterior approach: a CT-based analysis

BACKGROUND:

Anatomical landmarks for templating of total hip arthroplasty (THA) that are visible both during surgery and on radiographs are rare. If surgery is performed through a direct anterior approach the external obturator tendon (EO) is consistently visible. To use this point as a reference the exact position and dimensions of the footprint need to be known.

AIM:

To determine the location and dimension of the EO footprint on pelvic radiographs by correlating the EO anatomy in CT scans with conventional radiographs.

METHODS:

CT scans and radiographs of 200 patients were analysed. The EO tendon was identified on CT scans; the height of its footprint, and its distance to the tip of the greater trochanter and to the anatomical axis of the femur was measured. The accuracy and inter-rater reliability in the identification of the EO footprint was determined.

RESULTS:

The EO tendon was visible on all CT scans and it's footprint was identifiable on all corresponding radiographs. It's cranio-caudal dimension was 6.4 ± 1.4 mm. It's distance to the tip of the greater trochanter was 16.0 ± 3.1 mm. The EO footprint was located 5.2 ± 3.7 mm lateral to the femoral anatomical axis. There was no significant difference regarding the accuracy of EO footprint localisation on radiographs among the 2 readers.

CONCLUSION:

The EO footprint on the greater trochanter is consistently visible on CT scans and radiographs. As the variability of the footprint dimension is small, this structure may serve as a useful landmark in THA, particularly when performed through a direct anterior approach.

Measurement of Patient's Perception on Limb-Length Discrepancy Compared With Weight-Bearing Orthoroentgenography in Total Hip Arthroplasty: A Prospective Study

BACKGROUND

Aims of this study included providing a comparison of the measurement of limb-length discrepancy after primary total hip arthroplasty between patient's perception and weight-bearing orthoroentgenographic measurement. A comparison between patient's perception and pelvic radiographic measurement was examined as well.

METHODS

This prospective study comprised patients who had already undergone total hip arthroplasty and were receiving postoperative outpatient care between April 2017 and July 2017. Block test was used to assess patient's perception on limb-length discrepancy. Weight-bearing orthoroentgenography and pelvic radiography were used for radiographic measurement. These 3 measurements were compared to find the difference, correlation, and reliability.

RESULTS

Evaluations were carried out on 68 patients subsequent to primary total hip arthroplasty. The prevalence of limb-length discrepancy by orthoroentgenographic, patient's perception, and pelvic radiographic measurements was 60%, 57.35%, and 52.94%, respectively. Mean difference of limb-length discrepancy between the 3 measurements were not statistically significant. When compared with orthoroentgenography, sensitivity and specificity of patient's perception measurement were 60.98% and 48.15%, respectively. Likewise, sensitivity and specificity of pelvic radiographic measurement were 78.05% and 85.19%, respectively. Poor correlation and reliability were found between orthoroentgenographic and patient's perception measurement (concordance correlation coefficient = 0.21, intraclass correlation coefficient = 0.22). However, good correlation and reliability were found between orthoroentgenographic and pelvic radiographic measurement (concordance correlation coefficient = 0.85, intraclass correlation coefficient = 0.85).

CONCLUSION

Patient's perception on limb-length discrepancy had poor correlation and reliability, low sensitivity and specificity when compared with orthoroentgenographic measurement. A physician should additionally perform measurement by orthoroentgenography or pelvic radiography.

Patient-reported outcomes in patients who undergo total hip arthroplasty after periacetabular osteotomy

BACKGROUND

There has been constant discussion about whether the clinical outcome of THA after periacetabular osteotomy (PAO) is equivalent to that after primary total hip arthroplasty (THA). However, there have been few reports about patient-reported outcomes (PRO) for those who undergo THA after PAO. We compared the pre- and postoperative PRO of patients who underwent THA after PAO and those who underwent primary THA alone.

METHODS

We performed a case-control study. Twenty-seven patients (29 hips) underwent THA after PAO (osteotomy group); their mean age at surgery was 57.2 years, and they underwent postoperative follow-up for a mean period of 3.0 years. For the control group, after matching age, sex, and Crowe classification, we included 54 patients (58 joints) who underwent primary THA for hip dysplasia. Assessment performed preoperatively and at the last follow-up included the Harris hip score, the Short Form 36 (SF-36) for the Physical Component Summary (PCS), Mental Component Summary (MCS), and Role/Social Component Summary (RCS) domains, Japanese Orthopaedic Association Hip-Disease Evaluation Questionnaire (JHEQ) for pain, movement, and mental health, and the visual analog scale (VAS) score of hip pain and satisfaction.

RESULTS

The two groups demonstrated no significant difference in the preoperative Harris hip score, each domain of the SF-36, JHEQ, and the VAS score of hip pain and satisfaction. The osteotomy group demonstrated significantly poor Harris hip scores for gait and activity, and JHEQ for movement at the last follow-up. There was no significant difference in each domain of the SF-36 and the VAS score of hip pain and satisfaction at the last follow-up.

CONCLUSION

Previous PAO affects the quality of physical function in patients who undergo subsequent THA.

Risk factors for conversion surgery to total hip arthroplasty of a hemiarthroplasty performed for a femoral neck fracture

INTRODUCTION

The purpose of this study was to determine risk factors for conversion to total hip arthroplasty (THA) in patients originally treated with hemiarthroplasty (HA) for displaced femoral neck fractures.

METHODS

In this case-controlled study, we identified 54 patients who were treated with HA for femoral neck fracture (FNF) who subsequently underwent conversion to THA at our institution between 2003 and 2013. We randomly selected 142 control patients who underwent HA for a displaced FNF without conversion surgery during the same time period. We compared demographic data, implant parameters, and radiographic data between the groups to identify risk factors for conversion surgery.

RESULTS

In the univariate analysis, younger age at index surgery (mean 75 vs. 80 years, p = 0.006), higher body mass index (26.1 vs. 23.7, p = 0.031), bipolar prosthesis (20% vs. 36%, p = 0.024), absence of dementia (6% vs. 23%, p = 0.01), increased leg length compared to contralateral limb (6.5 mm vs. 0.2 mm, p<0.001), and increased HA femoral head size compared to the contralateral femoral head (2.7 mm vs. 1.5 mm, p = 0.02) were associated with a significantly increased risk of conversion surgery. In the multivariate logistic regression, decreased age at index surgery, no dementia, use of a bipolar head, and increased leg length discrepancy (LLD) were associated with risk of conversion.

CONCLUSIONS

Patient characteristics, including younger age, increased BMI, and absence of dementia can lead to increased risk for conversion of HA to THA. Intraoperative considerations of head size and increase in ipsilateral LLD may increase the risk of conversion surgery. These factors should be considered by surgeons who employ HA for displaced FNFs.

Additive Influence of Hip Offset and Leg Length Reconstruction on Postoperative Improvement in Clinical Outcome After Total Hip Arthroplasty

BACKGROUND

There is a lack of prospective studies investigating the additive effect of both acetabular and femoral reconstruction parameters on the functional outcome following total hip arthroplasty (THA).

METHODS

The aim of this prospective cohort study was to determine the combined influence of hip geometry reconstruction and component positioning on the clinical outcome following primary THA for unilateral osteoarthritis. We prospectively assessed the clinical outcome and radiographic parameters for hip geometry reconstruction, component position, and orientation using validated measurements for the operated hip compared to the contralateral native hip in a consecutive series of 113 patients with primary unilateral cementless THA. The correlation of reconstruction parameters was investigated using a multivariate polynomial regression model for the dependent variable ΔHHS (difference between the Harris hip scores preoperatively and 2.0-4.8 years postoperatively). Target zones for hip reconstruction and component positioning were investigated for an association with superior clinical outcome.

RESULTS

The regression model demonstrated a significant correlation for the ΔHHS and both hip offset (HO) reconstruction and leg length difference. Patients with accurate to slightly increased HO reconstruction combined with balanced leg length demonstrated a significantly higher ΔHHS than patients outside this zone (HO: 5 ± 5 and LLD: 0 ±5 mm, P = .029). This finding could be confirmed for 2 enlarged zones (zone 1: HO, 7.5 ± 7.5 and LLD, 2.5 ± 7.5 mm, P = .028; zone 2: HO, 7.5 ± 7.5 and LLD, 7.5 ± 7.5 mm, P = .007).

CONCLUSION

HO and leg length reconstruction demonstrated an additive effect on clinical outcome and surgeons should aim for high accuracy in the reconstruction of both factors.

Shoe Lifts for Leg Length Discrepancy in Adults With Common Painful Musculoskeletal Conditions: A Systematic Review of the Literature

OBJECTIVE

To determine whether shoe lifts effectively treat leg length discrepancy (LLD)-associated morbidities in adults with common painful musculoskeletal conditions.

DATA SOURCES

Trip database, Cochrane Central Register of Controlled Trials database, PubMed database, Physiotherapy Evidence Database, and National Guideline Clearinghouse database. The search was performed in September 2017, was limited to English only, and had no time constraints.

STUDY SELECTION

Two reviewers independently determined study eligibility. Inclusion criteria were (1) participants ≥18 years old with musculoskeletal-related complaints and LLD; (2) a shoe lift intervention was used; and (3) the study reported on pain, function, range of motion, patient satisfaction, quality of life, or adverse events. Randomized controlled trials (RCTs) and controlled intervention, cohort, before-and-after, case series, and case report studies were included. Three-hundred and nineteen articles were screened, and 9 guidelines were reviewed.

DATA EXTRACTION

We extracted data pertaining to participant demographic characteristics, study setting, recruitment, randomization, method of LLD measurement, shoe lift characteristics, treatment duration, and outcome measures. We included 10 studies, including 1 RCT.

DATA SYNTHESIS

LLD was associated with low back pain, scoliosis, and osteoarthritis of the hip and knee. Description of LLD correction strategy was often inadequate. Study quality was very low or poor. In non-RCT studies reporting on the proportion of participants who improved with a shoe lift, 88%±3% of 349 participants treated had partial or complete pain relief (effect size range, 66.7%-100%). All 22 RCT participants receiving treatment experienced pain relief (mean pain reduction, 27±9mm on a 150-mm visual analog scale). Two of 9 guidelines recommended shoe lift use based on consensus and were of moderate-to-high quality.

CONCLUSIONS

There is low-quality evidence that shoe lifts reduce pain and improve function in patients with LLD and common painful musculoskeletal conditions. High-quality research evaluating a threshold LLD to correct and a strategy to do so is necessary. Developing an appropriate comparison group to test clinically relevant outcome measures would make a valuable contribution in this regard.

Risk factors for conversion surgery to total hip arthroplasty of a hemiarthroplasty performed for a femoral neck fracture

INTRODUCTION

The purpose of this study was to determine risk factors for conversion to total hip arthroplasty (THA) in patients originally treated with hemiarthroplasty (HA) for displaced femoral neck fractures.

METHODS

In this case-controlled study, we identified 54 patients who were treated with HA for femoral neck fracture (FNF) who subsequently underwent conversion to THA at our institution between 2003 and 2013. We randomly selected 142 control patients who underwent HA for a displaced FNF without conversion surgery during the same time period. We compared demographic data, implant parameters, and radiographic data between the groups to identify risk factors for conversion surgery.

RESULTS

In the univariate analysis, younger age at index surgery (mean 75 vs. 80 years, p = 0.006), higher body mass index (26.1 vs. 23.7, p = 0.031), bipolar prosthesis (20% vs. 36%, p = 0.024), absence of dementia (6% vs. 23%, p = 0.01), increased leg length compared to contralateral limb (6.5 mm vs. 0.2 mm, p<0.001), and increased HA femoral head size compared to the contralateral femoral head (2.7 mm vs. 1.5 mm, p = 0.02) were associated with a significantly increased risk of conversion surgery. In the multivariate logistic regression, decreased age at index surgery, no dementia, use of a bipolar head, and increased leg length discrepancy (LLD) were associated with risk of conversion.

CONCLUSIONS

Patient characteristics, including younger age, increased BMI, and absence of dementia can lead to increased risk for conversion of HA to THA. Intraoperative considerations of head size and increase in ipsilateral LLD may increase the risk of conversion surgery. These factors should be considered by surgeons who employ HA for displaced FNFs.

What are the six degree-of-freedom errors of a robotically-machined femoral cavity in total hip arthroplasty and are they clinically important? An in-vitro study

Errors during a robot-assisted THA may result in a femoral cavity with position and orientation different than planned. This can lead to a femoral component placement that inaccurately sets a patient's femoral anteversion (FA), femoral offset (FO), and vertical offset (VO). The objectives of this study were to determine the position and orientation errors of robotically-machined femoral cavities in six degrees of freedom and to determine how position and orientation errors translate into errors in the setting of FA, FO, and VO. After creating preoperative plans, robot-assisted THAs were performed on twelve cadaveric specimens. The position and orientation of the machined cavities were compared to those of the planned cavities to determine the errors in six degrees of freedom. Placement of femoral components into the machined cavities was simulated, and the differences in FA, FO, and VO between the simulated and planned component placement were computed. While bias (i.e. mean error) occurred for three of six degrees of freedom in femoral cavities machined by a robotic system, the root mean squared errors (RMSEs) when the placement of femoral component was simulated were limited to 1.9° for FA, 1.0mm for FO, and 2.1mm for VO and were clinically unimportant.

Surgical accuracy, function, and quality of life of simultaneous versus staged bilateral Total hip Arthroplasty in patients with Osteonecrosis of the femoral head

BACKGROUND

The optimal surgical option for patients requiring bilateral hip replacement remains controversial. The purpose of this study was to compare surgical accuracy; functional outcome and health-related quality of life; and prosthetic-related complications and revision surgery of a simultaneous bilateral total hip arthroplasty (THA) with those of a staged bilateral THA with an interval between procedures <12 months.

METHODS

A total of 123 unselected consecutive patients (mean age, 43.3 years) who underwent bilateral THAs for osteonecrosis of the femoral head (ONFH) with a minimum follow-up of two years (mean, 60.2 months) were studied retrospectively; 63 simultaneous procedures served as a test group and 60 staged procedures served as a control group.

RESULTS

The mean postoperative leg-length discrepancy (LLD) and the percentage of patients who had an LLD >3 mm were significantly lower in the simultaneous group (P < 0.001 and P = 0.001, respectively). A higher number of cups within the safe zones, a higher correction rate, and a lower failure rate for the cup placement in the second-operated hip were also identified in the simultaneous group. The mean Harris hip score, EuroQol-5D index, and EuroQol-visual analogue scale score were all better in the simultaneous group at the latest follow-up (P < 0.001, in all comparisons). We found that the simultaneous procedure was associated with a lower incidence of postoperative prosthetic-related complications and revision surgery.

CONCLUSIONS

We suggest that bilateral ONFH could be treated with a simultaneous THA rather than a staged THA to achieve a better surgical outcome.

Gait Kinematic Deviations in Patients With Developmental Dysplasia of the Hip Treated With Total Hip Arthroplasty

Comprehensive gait analysis of patients with Crowe type II and III developmental dysplasia of the hip (DDH) after successful total hip arthroplasty (THA) is lacking in the literature. This study evaluated gait function in joint kinematics after unilateral and bilateral THA in patients with DDH. In addition, the effect of high cup position on gait function was investigated. A total of 16 unilateral and 15 bilateral cementless THA patients due to DDH and 10 healthy participants comprised the study population. Levels of superior displacement of the acetabular cup and leg-length discrepancy after THA were measured. Three-dimensional gait analysis for patients who underwent THA was performed at least 1 year postoperatively. Range of motion (ROM), particularly sagittal (flexion/extension) and frontal (adduction/abduction) hip joint ROM, was significantly lower in both the unilateral and bilateral groups than in healthy participants. Sagittal (flexion/extension) hip ROM in patients with DDH was greater in the unilateral group than in the bilateral group. A significant influence of high acetabular cup position on hip joint kinematics was not observed in the unilateral subgroups (mean level of cup superior displacement was 11.8 mm). In contrast, a significant influence of high acetabular cup position on hip joint kinematics was observed in the bilateral subgroups (mean level of cup superior displacement was 21.3 mm). The functional symmetry and cup superior displacement within 12 mm in patients with DDH after unilateral THA contributed to the restoration of normal hip biomechanics. [Orthopedics. 2017; 40(3):e425-e431.].

What do we get from navigation in primary THA?

Navigation in primary total hip arthroplasty has a history of over 20 years. During this process, imageless computer navigation can be particularly helpful in optimally restoring the hip’s biomechanics. This involves the accurate placement of the acetabular component with the determination of the anteversion and abduction, whereby the navigated femur-first technique also allows for a calculation of the combined anteversion. Additional critical parameters such as the reconstruction of the rotation centre, as well as the femoral and acetabular offset, can also be optimally adjusted. Last but not least, an intra-operative evaluation and equalisation of the leg length is possible.

Nonetheless, the disadvantages of this surgical technique in terms of the high costs in the acquisition and preservation of the necessary devices, as well as the longer operation time, must be taken into account. However, economic aspects are not the only thing preventing widespread use of the navigation technique. Determining the plane of reference (APP) for the optimal orientation of the implants is based on palpation of the bony landmarks – and this is influenced by the thickness of the soft tissue layer. Furthermore, the experience of the surgeon constitutes a variable that influences the accuracy of navigation.

In summary, hip navigation certainly offers an interesting technique for the optimisation of total hip arthroplasty with reconstruction of proper biomechanics. At the same time, there is currently a lack of high-quality randomised controlled long-term trials that evaluate the clinical advantage for the patients, together with cost utility and survival rates.

Cite this article: Renner L, Janz V, Perka C, Wassilew GI. What do we get from navigation in primary THA? EFORT Open Rev 2016;1:205-210. 10.1302/2058-5241.1.000034.

The Femoral Head Center Shifts in a Mediocaudal Direction During Aging

BACKGROUND

Accurate reconstruction of hip joint biomechanics is the key stone in total hip arthroplasty. Although proximal femur morphology is known to vary with both age and gender, few studies investigated this in the very elderly (ie, ≥80 years). The purpose of this study was to compare basic morphological parameters describing the position of the femoral head between very elderly and middle-aged subjects.

METHODS

Computed tomographic scans of the femur of 90 very elderly (mean 84 years, range 80-105 years) and 58 middle-aged subjects (mean 52 years, range 20-79 years) were made. After 3-dimensional reconstruction, the neck-shaft angle, femoral neck anteversion angle, femoral head height, femoral neck length, and mediolateral offset (ML-offset) were determined.

RESULTS

The neck-shaft angle was on average 3.6° less in elderly males (125.9° ± 5.0°) than in middle-aged males (129.5° ± 5.1°) (P < .001). The femoral neck anteversion angle was not significantly different between both age and gender groups. The femoral head height was -12.3 mm in elderly females compared to -10.5 mm (Δ 17%) in elderly males (P = .284) and even -8.0 mm (Δ 54%) in middle-aged males. The ML-offset was 10% (4.1 mm) larger in elderly compared to middle-aged males (P < .001).

CONCLUSION

These findings suggest that the femoral neck and head shift in a relative varus position during aging. Femoral prostheses with increased ML-offset and a lower caput-collum-diaphyseal angle are needed to accommodate the morphology of the femur in the very elderly. Care must be taken not to lengthen the operated leg, particularly in very elderly females.

Comparative Analysis of Radiographic Hip Joint Geometry Using Measurement Tools on Picture Archiving and Communication System: A Prospective Study of 100 Pelvic Radiographs of Koreans

BACKGROUND

A contralateral normal hip joint has been often used as a reference standard in preoperative planning and intraoperative assessment of hip arthroplasty, with the assumption that bilateral hip joint geometries have no significant differences. However, one previous study using analog measurements on hardcopy films reported significant bilateral variation in hip joint geometry. We therefore investigated the level of agreement between the right and left hips for each measurement and determined index values and the range of normal bilateral variations.

METHODS

We assessed 100 standard anteroposterior radiographs of the pelvis in this study. Two independent observers measured the actual value of femoral head diameter, location of the femoral head center, acetabular offset, femoral offset, hip offset, greater trochanteric height, neck-shaft angle, medullary canal diameter, and proximal femoral diameter. Intraclass correlation coefficients (ICCs) and values of mean difference were calculated for each measurement.

RESULTS

The results demonstrated perfect agreement (ICC >0.8) between the right and left hips for most parameters and substantial agreement for greater trochanteric height (ICC = 0.735) and femoral offset (ICC = 0.773). The mean difference and standard deviation in the measurement between the right and left hips for the location of the femoral head center and the acetabular offset were 0.60 ± 0.48 mm and 0.42 ± 0.30 mm, respectively.

CONCLUSION

Hip joint geometry is not influenced by side. In hip arthroplasty, a contralateral normal hip can be reliably used as a guide for preoperative planning using measurement tools on a picture archiving and communication system.

Identifying the procedural gap and improved methods for maintaining accuracy during total hip arthroplasty

Osteoarthritis is a ubiquitous condition, affecting 26 million Americans each year, with up to 17% of adults over age 75 suffering from one variation of arthritis. The hip is one of the most commonly affected joints and while there are conservative options for treatment, as symptoms progress, many patients eventually turn to surgery to manage their pain and dysfunction. Early surgical options such as osteotomy or arthroscopy are reserved for younger, more active patients with less severe disease and symptoms. Total hip arthroplasty offers a viable solution for patients with severe degenerative changes; however, post-surgical discrepancies in leg length, offset and component malposition are common and cause significant complications. Such discrepancies are associated with consequences such as low back pain, neurological deficits, instability and overall patient dissatisfaction. Current methods for managing leg length and offset during hip arthroplasty are either inaccurate and susceptible to error or are cumbersome, expensive and lengthen surgical time. There is currently no viable option that provides accurate, real-time data to surgeons regarding leg length, offset and cup position in a cost-effective manner. As such, we hypothesize that a procedural gap exists in hip arthroplasty, a gap into which fall a large majority of arthroplasty patients who are at increased risk of complications following surgery. These complications and associated treatments place significant stress on the healthcare system. The costs associated with addressing leg length and offset discrepancies can be minor, requiring only heel lifts and short-term rehabilitation, but can also be substantial, with revision hip arthroplasty costs of up to $54,000 per procedure. The need for a cost-effective, simple to use and unobtrusive technology to address this procedural gap in hip arthroplasty and improve patient outcomes is of increasing importance. Given the aging of the population, the projected increases in the volume of procedures over the coming decades and the economic pressures associated with downward pricing pressure and bundled payments, the need to address this gap is underscored.