[Complications after minimally invasive total hip arthroplasty]

Treatment of pre-collapse non-traumatic osteonecrosis of the femoral head through Orthopdische Chirurgie München approach combined with autologous bone mixed with β-tricalcium phosphate porous bioceramic bone graft: a retrospective study of mid-term results

Background

This study aimed to evaluate the clinical efficacy of femoral head and neck fenestration combined with autologous bone mixed with β-tricalcium phosphate porous bioceramic bone (light bulb procedure) through Orthopdische Chirurgie München approach (OCM approach) for pre-collapse non-traumatic osteonecrosis of the femoral head(ONFH).

Methods

The clinical data of 47 patients (47 hips) with ONFH were retrospectively reviewed. The Harris hip score (HHS) was used to evaluate the clinical outcomes. Imaging was assessed by X-ray. Clinical failure was defined as postoperative total hip arthroplasty (THA) or the HHS was poor (< 70). The Kaplan–Meier survival curve was used to conduct a univariate analysis of risk factors. The analysis factors included gender, age, International Association Research Circulation Osseous (ARCO) stage, etiology, body mass index (BMI), 25-hydroxyvitamin D (25(OH)D), and type I collagen carboxy-terminal peptide (CTX). The COX multivariate risk model was used to analyze the risk factors.

Results

All the 47 hips were followed up for 24–58 months, with an average of 45 months. The Harris score (76.29 ± 10.38) at the last follow-up was significantly higher than the preoperative HHS (64.45 ± 2.93) (P < 0.05). The postoperative HHS was excellent with a success rate of 36.17%. Postoperative imaging evaluation showed that 9 hips improved, 28 hips stabilized, and 10 hips progressed. Moreover, 17 out of 47 hips were defined as a postoperative clinical failure and the success rate was 63.83%. 25(OH)D and preoperative ARCO stage were risk factors for postoperative clinical failure (P < 0.05). The COX multivariate risk model analysis showed that IIIA stage was an independent risk factor for postoperative clinical failure (P < 0.05).

Conclusions

The head and neck fenestration and bone grafting via the OCM approach in the treatment of non-traumatic ONFH in the pre-collapse stage can achieve good clinical outcomes. 25(OH)D deficient patients and ARCO IIIA patients had a higher failure rate of bone graft using this approach.

Is the cup orientation different in bilateral total hip arthroplasty with right-handed surgeons using posterolateral approach?

Background

The impact of surgeon handedness on acetabular cup orientation in total hip arthroplasty (THA) is not well studied. The aim of our study is to investigate the difference of cup orientation in bilateral THA performed by right-handed surgeons using posterolateral approach and which cup could be fitter to Lewinneck’s safe zone.

Methods

The study consisted of 498 patients that underwent bilateral THA by three right-handed surgeons in our hospital. Postoperative acetabular cup anteversion and abduction on an anteroposterior pelvic radiograph were measured by Orthoview software (Orthoview LLC, Jacksonville, Florida). Furthermore, the percentage of cup placement within the safe zone was compared.

Results

The mean anteversion was 25.28 (25.28° ± 7.16°) in left THA and 22.01 (22.01° ± 6.35°) in right THA (p < 0.001). The mean abduction was 37.50 (37.50° ± 6.76°) in left THA and 38.59 (38.59° ± 6.84°) in right THA (p = 0.011). In the left side, the cup was positioned in Lewinnek’s safe zone in 52% for anteversion, 87% for abduction, and 46% for both anteversion and abduction. But the cup placement within Lewinnek’s safe zone was 71, 88, and 62% in the right side, respectively. There were significant differences in the percentage of acetabular cup placement within the safe zone for anteversion (p < 0.001) and for both anteversion and inclination (p < 0.001). Dislocation occurred in 7.0% (35/498) of cases in left THA and 3.2% (16/498) in right THA. The percentages of patients experiencing dislocation were significantly different between the two sides (p = 0.006).

Conclusions

This current study demonstrated that surgeon handedness is likely to be a contributing factor that affects cup inclination and anteversion in bilateral THA and that the placement of cup performed by dominant hands of surgeons is more accurate than that performed by non-dominant sides.

Posterior lesser trochanter line should not be used as reference for assessing femoral version in CT scans: a retrospective reliability and agreement study

Background The estimation of femoral version in preoperative planning of total hip arthroplasty and to assess complications after total hip arthroplasty is crucial. Recent studies have recommended the posterior lesser trochanter line as an intraoperative reference for estimating femoral version. We hypothesized, that if there is a correlation, the posterior lesser trochanter line could be used to assess femoral version in computed tomography (CT) scans. Purpose To evaluate the correlation between the posterior lesser trochanter line and the posterior femoral condyle axis. Material and Methods CT scans of 126 patients after unilateral total hip arthroplasty were analyzed by means of a newly developed digital planning software for CT scans. Both hips were measured, the angle between the posterior lesser trochanter line and the posterior femoral condyle axis was determined, and the relationship between both lines was evaluated. Results We found significant differences between male and female patients ( P < 0.001) and between left and right femora ( P = 0.001). There was no significant difference between healthy hips and hips with osteoarthritis after total hip arthroplasty ( P = 0.901). Conclusion There is no reliable correlation between posterior lesser trochanter line and posterior femoral condyle axis. Therefore, posterior lesser trochanter line should not be used to assess femoral version in CT scans. As a consequence, the gold standard for measuring femoral version should still be a three-dimensional CT scan of the whole femur.

Navigation is Equal to Estimation by Eye and Palpation in Preventing Psoas Impingement in THA

BACKGROUND

Iliopsoas tendon impingement is one possible reason for persistent groin pain and diminished functional outcome after THA. So far, estimation by eye and palpation is the standard procedure to intraoperatively assess the distance of the cup to the anterior rim. However, novel technologies such as imageless navigation enable intraoperative measurements of the cup in relation to the psoas tendon and bony landmarks.

QUESTIONS/PURPOSES

We asked whether psoas impingement (1) can be reduced using imageless navigation compared with the standard technique and (2) is associated with specific patient characteristics. Furthermore, we investigated (3) if anterior cup protrusion (overhang) is associated with lower outcome scores for pain and function.

METHODS

The current study is a reanalysis of data from a randomized controlled trial evaluating navigation for THA; 135 patients were randomized for surgery with or without the use of imageless navigation. The risk for anterior protrusion of the cup above the acetabular rim and thus potential psoas impingement, defined as an overhang of the cup above the anterior acetabular rim as measured on postoperative CT, was either controlled with the help of navigation or standard control by eye and palpation intraoperatively. Postoperatively, the anterior protrusion of the cup above the acetabular rim was measured on three-dimensional (3-D) CT by a blinded, external institute. In addition to patient-related outcome measures, the Harris hip score, Hip disability and Osteoarthritis Outcome Score, and EuroQol were obtained 1 year postoperatively. Altogether 123 data sets were available for primary analysis and 115 were available for 1-year followup.

RESULTS

There was no difference, with the numbers available, between the navigated and the control groups in terms of the mean distance of the cup below the anterosuperior acetabular rim (3.9 mm; -5.3 to 12.6 mm versus 4.4 mm; -7.9 to 13.7 mm; p = 0.72) or the anteroinferior acetabular rim (4.7 mm; -6.2 to 14.8 mm versus 4.2 mm; -7.1 to 16.3 mm; p = 0.29). There was no difference, with the numbers available, in terms of the proportion of cups with anterior overhang (7%, four of 57 versus, 15%, 10 of 66; p = 0.16), respectively. After controlling for potential confounding variables such as cup inclination, cup size, patient age, BMI, stage of arthritis, and length of skin incision, we found cup anteversion (hazard ratio [HR], 0.87; 95% CI, 0.81-0.93; p < 0.001) and female sex (HR, 3.88; 95% CI, 1.01-14.93; p = 0.049) were associated with a propensity to potential psoas impingement. With the numbers available, there were no differences observed in clinical scores between groups with and without anterior cup protrusion.

CONCLUSIONS

We found no differences between imageless navigation and estimation by eye and palpation in preventing potential psoas impingement. Despite the comparable clinical outcome for patients with and without cup protrusion, the orthopaedic surgeon should be especially aware of propensity for psoas impingement in women.

LEVEL OF EVIDENCE

Level II, therapeutic study.

Even the Intraoperative Knowledge of Femoral Stem Anteversion Cannot Prevent Impingement in Total Hip Arthroplasty

BACKGROUND

In this prospective study of 66 patients undergoing cementless total hip arthroplasty through a minimally invasive anterolateral approach, we evaluated the impact of an intraoperative hybrid combined anteversion technique on postoperative range of motion (ROM).

METHODS

After navigation of femoral stem anteversion, trial acetabular components were positioned manually, and their position recorded with navigation. Then, final components were implanted with navigation at the goals prescribed by the femur-first impingement detection algorithm. Postoperatively, three-dimensional computed tomographies were performed to determine achieved component position and model impingement-free ROM by virtual hip movement, which was compared with published values necessary for activities of daily living. This model was run a second time with the implants in the position selected by the surgeon rather than the navigation program. In addition, we researched into risk factors for ROM differences between the freehand and navigated cup position.

RESULTS

We found a lower flexion of 8.3° (8.8°, P < .001) and lower internal rotation of 9.2° (9.5°, P < .001) for the freehand implanted cups in contrast to a higher extension of 9.8° (11.8°, P < .001) compared with the navigation-guided technique. For activities of daily living, 58.9% (33/56) in the freehand group compared with 85.7% (48/56) in the navigation group showed free flexion (P < .001) and similarly 50.0% (28/56) compared with 76.8% (43/56) free internal rotation (P < .001). Body mass index, incision length, and cup size were identified as independent risk factors for reduced flexion and internal rotation in the freehand group.

CONCLUSION

For implementation of a combined anteversion algorithm, intraoperative alignment guides for accurate cup positioning are required using a minimally invasive anterolateral approach. Obese patients are especially at risk of cup malpositioning.

Novel measurement method on plain radiographs to predict postoperative stem anteversion in cementless THA

Preoperative knowledge of femoral stem anteversion can reduce instability and impingement especially using the standard "cup first" technique in cementless total hip arthroplasty (THA). In this study, we asked whether stems at risk of retroversion or high anteversion (>20°) can be detected preoperatively using hip radiographs in two planes (anteroposterior and Lauenstein). In 123 patients undergoing cementless THA using a non-anatomic, non-modular, straight stem, low centered hip radiographs in two planes were obtained preoperatively and three-dimensional computed tomography (3D-CT) 6 week postoperatively. The novel developed Isthmus Ratio (iRatio) as the relation between canal isthmus and calcar isthmus in the anteroposterior and Lauenstein view was calculated by two observers twice in a 6-week interval. iRatio was compared to postoperative 3D-CT stem version measured by an independent and blinded, external institute. We found a correlation between mean radiographic iRatio and 3D-CT stem torsion of r = 0.578 (p < 0.0001). The observers had excellent agreements within (ICC ≥0.918) and between (mean CCC = 0.967) radiographic iRatio measurements. Eighty-one percent (21/26) of the retroverted cementless stems had a preoperative iRatio below 0.35 and 91% (10/11) of stems with an anteversion exceeding 20° an iRatio above 0.55, respectively. The novel iRatio represents a feasible and reliable method for analyzing anteversion of the final stem on plain radiographs before cementless THA with a straight, tapered stem. iRatios below 0.35 and above 0.55 represent a warning of retroversion and anteversion more than 20° of the final stem, respectively. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 34:2025-2030, 2016.

Leg length and offset differences above 5mm after total hip arthroplasty are associated with altered gait kinematics

We aimed to investigate the relationship between postoperative leg length/offset (LL/OS) reconstruction and gait performance after total hip arthroplasty (THA). In the course of a prospective randomized controlled trial, 60 patients with unilateral hip arthrosis received cementless THA through a minimally-invasive anterolateral surgical approach. One year post-operatively, LL and global OS restoration were analyzed and compared to the contralateral hip on AP pelvic radiographs. The combined postoperative limb length/OS reconstruction of the operated hip was categorized as restored (within 5mm) or non-restored (more than 5mm reduction or more than 5mm increment). The acetabular component inclination, anteversion and femoral component anteversion were evaluated using CT scans of the pelvis and the femur. 3D gait analysis of the lower extremity and patient related outcome measures (HHS, HOOS, EQ-5D) were obtained pre-operatively, six months and twelve months post-operatively by an observer blinded to radiographic results. Component position of cup and stem was comparable between the restored and non-restored group. Combined LL and OS restoration within 5mm resulted in higher Froude number (p<0.001), normalized walking speed (p<0.001) and hip range-of-motion (ROM) (p=0.004) during gait twelve months postoperatively, whereas gait symmetry was comparable regardless of LL and OS reconstruction at both examinations. Clinical scores did not show any relevant association between the accuracy of LL or OS reconstruction and gait six/twelve months after THA. In summary, postoperative LL/OS discrepancies larger than 5mm relate to unphysiological gait kinematics within the first year after THA. DRKS00000739, German Clinical Trials Register.

Visual intraoperative estimation of range of motion is misleading in minimally invasive total hip arthroplasty

INTRODUCTION

Generally range of motion (ROM) in total hip arthroplasty (THA) is intraoperatively assessed by eye. Can we assume that visual estimation of ROM is reliable?

METHODS

60 patients underwent cementless THA in a subgroup analysis of a clinical prospective trial using a minimally invasive anterolateral approach in lateral decubitus position. Four experienced surgeons intraoperatively estimated ROM visually by assessment of the femur relative to the alignment of the patient's pelvis. These estimations were compared with computer navigation measurements.

RESULTS

We found a mean difference between navigation measurements and intraoperative estimations by eye of -5.6° (±10.9°; -17° to 30°) for flexion, respectively, -0.4° (±10.7°; -24° to 30°) for extension, 8.7° (±9.0°; -10° to 34°) for abduction, 5.9° (±18.3°; -58° to 68°) for external rotation and -5.8° (±12.1°; -38° to 22°) for internal rotation. Multivariate analysis showed no association between the visual accuracy of estimation of ROM and patient characteristics, such as BMI, sex, grade of osteoarthritis and treatment side except for a significant correlation of visual accuracy of estimation of extension and the level of professional experience. Otherwise, the level of professional experience had no impact on the accuracy of estimation of ROM by eye.

CONCLUSIONS

Even the experienced surgeon's intraoperative estimation of ROM by eye is not reliable and differs up to 30° compared to objective measurements in minimally invasive THA. For accurate intraoperative assessment of ROM, the use of technical devices is recommended.

TRIAL REGISTRATION

DRKS00000739.

Accuracy of measuring acetabular cup position after total hip arthroplasty: comparison between a radiographic planning software and three-dimensional computed tomography

PURPOSE

Various methods are available for measuring acetabular cup position after total hip arthroplasty (THA) on standard anterior-posterior (AP) radiographs. We compared the accuracy of a commercial radiographic planning software program with that of three-dimensional computed tomography (3D-CT) scans.

METHODS

We obtained plain AP radiographs and 3D-CTs from 65 patients after THA. In addition to calculating cup anteversion and inclination with 3D-CT, we determined the cup position using the radiographic planning software program mediCAD® 2.5 (Hectec, Niederviehbach, Germany). Furthermore, we compared the measurements using the inter-teardrop and bi-ischial lines as pelvic landmarks.

RESULTS

The mean difference in anteversion between 3D-CT and mediCAD® software was 0.1° using the inter-teardrop line (standard deviation [SD], 8.8°; range, -21° to 23°; p = 0.97) and 0.4° using the bi-ischial line (SD, 8.8°; range, -23° to 21°; p = 0.72). Inclination showed a mean difference of 0.6° using the inter-teardrop line (SD, 4.4°; range, -9° to 21°; p = 0.24) and 0.5° using bi-ischial line (SD, 4.6°; range, -9° to 22°; p = 0.35). The means for absolute differences were 7.2° for anteversion and 3.1° for inclination. With regard to using the bi-ischial or inter-teardrop line, no significant difference was found between the two pelvic landmarks. The intra-class correlation coefficient (ICC) was analysed for anteversion and inclination using either the inter-teardrop line or the bi-ischial line as radiographic baseline.

CONCLUSIONS

A radiographic planning software program (mediCAD®) is a helpful tool for measuring cup inclination on AP radiographs. With respect to anteversion, measurements are rather susceptible to mistakes with mean inaccuracies of over 7°. Thus, 3D-CT remains the "gold standard" if a lower tolerance limit (±3°) is required for more complex biomechanical evaluations. As a pelvic landmark, the interteardrop line is preferential to the bi-ischial line because of its lower impact on the position of the pelvis.

Visual intraoperative estimation of cup and stem position is not reliable in minimally invasive hip arthroplasty

Background and purpose - In hip arthroplasty, acetabular inclination and anteversion-and also femoral stem torsion-are generally assessed by eye intraoperatively. We assessed whether visual estimation of cup and stem position is reliable. Patients and methods - In the course of a subgroup analysis of a prospective clinical trial, 65 patients underwent cementless hip arthroplasty using a minimally invasive anterolateral approach in lateral decubitus position. Altogether, 4 experienced surgeons assessed cup position intraoperatively according to the operative definition by Murray in the anterior pelvic plane and stem torsion in relation to the femoral condylar plane. Inclination, anteversion, and stem torsion were measured blind postoperatively on 3D-CT and compared to intraoperative results. Results - The mean difference between the 3D-CT results and intraoperative estimations by eye was -4.9° (-18 to 8.7) for inclination, 9.7° (-16 to 41) for anteversion, and -7.3° (-34 to 15) for stem torsion. We found an overestimation of > 5° for cup inclination in 32 hips, an overestimation of > 5° for stem torsion in 40 hips, and an underestimation < 5° for cup anteversion in 42 hips. The level of professional experience and patient characteristics had no clinically relevant effect on the accuracy of estimation by eye. Altogether, 46 stems were located outside the native norm of 10-20° as defined by Tönnis, measured on 3D-CT. Interpretation - Even an experienced surgeon's intraoperative estimation of cup and stem position by eye is not reliable compared to 3D-CT in minimally invasive THA. The use of mechanical insertion jigs, intraoperative fluoroscopy, or imageless navigation is recommended for correct implant insertion.

Current standard rules of combined anteversion prevent prosthetic impingement but ignore osseous contact in total hip arthroplasty

PURPOSE

In this prospective study of 135 patients undergoing cementless total hip arthroplasty (THA) we asked whether six current definitions of combined anteversion prevent impingement and increase postoperative patient individual impingement-free range-of-motion (ROM).

METHODS

Implant position was measured by an independent, external institute on 3D-CT performed six weeks post-operatively. Post-operative ROM was calculated using a CT-based algorithm detecting osseous and/or prosthetic impingement by virtual hip movement. Additionally, clinical ROM was evaluated pre-operatively and one-year post-operatively by a blinded observer.

RESULTS

Combined component position of cup and stem according to the definitions of Ranawat, Widmer, Dorr, Hisatome and Yoshimine inhibited prosthetic impingement in over 90 %, while combined osseous and prosthetic impingement still occurred in over 40 % of the cases. The recommendations by Jolles, Widmer, Dorr, Yoshimine and Hisatome enabled higher flexion (p ≤ 0.001) and internal rotation (p ≤ 0.006). Clinically, anteversion rules of Widmer and Yoshimine provided one-year post-operatively statistically but not clinically relevant higher internal rotation (p ≤0.034).

CONCLUSION

Standard rules of combined anteversion detect prosthetic but fail to prevent combined osseous and prosthetic impingement in THA. Future models will have to account for the patient-individual anatomic situation to ensure impingement-free ROM.