Randomized controlled trial of abductor muscle damage in relation to the surgical approach for primary total hip replacement: minimally invasive anterolateral versus modified direct lateral approach.

INTRODUCTION: Minimally invasive total hip arthroplasty (THA) is claimed to be superior to the standard technique, due to the potential reduction of soft tissue damage via a smaller and tissue-sparing approach. As a result of the lack of objective evidence of fewer muscle and tendon defects, controversy still remains as to whether minimally invasive total hip arthroplasty truly minimizes muscle and tendon damage. Therefore, the objective was to compare the influence of the surgical approach on abductor muscle trauma and to analyze the relevance to postoperative pain and functional recovery. MATERIALS AND METHODS: Between June 2006 and July 2007, 44 patients with primary hip arthritis were prospectively included in the study protocol. Patients underwent cementless unilateral total hip arthroplasty either through a minimally invasive anterolateral approach (ALMI) (n = 21) or a modified direct lateral approach (mDL) (n = 16). Patients were evaluated clinically and underwent MR imaging preoperatively and at 3 and 12 months postoperatively. Clinical assessment contained clinical examination, performance of abduction test and the survey of a function score using the Harris Hip Score, a pain score using a numeric rating scale (NRS) of 0-10, as well as a satisfaction score using an NRS of 1-6. Additionally, myoglobin and creatine kinase were measured preoperatively, and 6, 24 and 96 h postoperatively. Evaluation of the MRI images included fatty atrophy (rating scale 0-4), tendon defects (present/absent) and bursal fluid collection of the abductor muscle. RESULTS: Muscle and tendon damage occurred in both groups, but more lateral gluteus medius tendon defects [mDL 3/12mth.: 6 (37%)/4 (25%); ALMI: 3 (14%)/2 (9%)] and muscle atrophy in the anterior part of the gluteus medius [mean-standard (12): 1.75 ± 1.8; mean-MIS (12): 0.98 ± 1.1] were found in patients with the mDL approach. The clinical outcome was also poorer compared to the ALMI group. Significantly, more Trendelenburg's signs were evident and lower clinical scores were achieved in the mDL group. No differences in muscle and tendon damage were found for the gluteus minimus muscle. A higher serum myoglobin concentration was measured 6 and 24 h postoperatively in the mDL group (6 h: 403 ± 168 µg/l; 24 h: 304 ± 182 µg/l) compared to the ALMI group (6 h: 331 ± 143 µg/l; 24 h: 268 ± 145 µg/l). CONCLUSION: Abductor muscle and tendon damage occurred in both approaches, but the gluteus medius muscle can be spared more successfully via the minimally invasive approach and is accompanied by a better clinical outcome. Therefore, going through the intermuscular plane, without any detachment or dissection of muscle and tendons, truly minimizes perioperative soft tissue trauma. Furthermore, MRI emerges as an important imaging modality in the evaluation of muscle trauma in THA.

Age-related appearance of muscle trauma in primary total hip arthroplasty and the benefit of a minimally invasive approach for patients older than 70 years.

Old age is frequently associated with a poorer functional outcome after THA. This might be based upon muscular damage resulting from surgical trauma. Minimally invasive approaches have been widely promoted on the basis of the muscle sparing effect. The aim of the study was to evaluate of the functional outcome and the grade of fatty muscle atrophy of the gluteus medius muscle by magnetic-resonance-imaging (MRI) in patients undergoing minimally invasive or traditional THA. Forty patients (21 female, 19 male) underwent THA either via a modified direct lateral (mDL) or a minimally invasive anterolateral (ALMI) approach. Patients were evaluated clinically and by MRI in terms of age (< or ≥70 y) preoperatively and at three and 12 months postoperatively. The Harris hip score and Trendelenburg's sign were recorded and a survey of a pain (using a numeric rating scale of 0-10) and satisfaction score (using a numeric rating scale of 1-6) was performed. Fatty atrophy (FA) of gluteus medius muscle was rated by means of a five-point rating scale (0 indicates no fat and 4 implies more fat than muscle). Younger patients reached a significantly higher Harris hip score, lower pain score and lower rate of positive Trendelenburg's sign accompanied by a significantly lower rate of postoperative FA (P = 0.03; young: FA (MW) = (preop. / 3 / 12 months), 0.15 / 0.7 / 0.7; old: FA (MW) = 0.18 / 1.3 / 1.36). Older patients with an mDL-approach had the significantly lowest clinical scores, the highest rate of positive Trendelenburg's sign and also the highest rate of fatty atrophy (P = 0.03; FA (old) mDL: 1.8; ALMI: 0.7). Interestingly, no influence of the approach could be detected within the younger group. Patients older than 70 years had a poorer functional outcome and a higher postoperative extent of FA when compared to younger patients, which must be based upon a higher vulnerability and a reduced regenerative capacity of their skeletal muscle. Through a minimally invasive approach the muscle trauma in older patients can be effectively reduced and thus the functional outcome significantly improved. Incision and detachment of tendons and muscles should be strictly avoided.

Relationship between cup position and obturator externus muscle in total hip arthroplasty.

BACKGROUND: It is often challenging to find the causes for postoperative pain syndromes after total hip replacement, since they can be very allotropic. One possible cause is the muscular impingement syndrome. The most commonly known impingement syndrome is the psoas impingement. Another recently described impingement syndrome is the obturator externus muscle impingement. The aim of this study is to analyze pathological conditions of the Obturator externus and to show possible causes. METHODS: 40 patients who had undergone a total hip replacement were subjected to clinical and MRI examinations 12 months after the surgery. The Harris Hip Score (HHS) was used to analyze pain and function. Additionally, a satisfaction score and a pain score (VAS) were determined. The MRI allowed for the assessment of the spatial relation between the obturator externus muscle and the acetabulum. Also measured were the acetabular inclination angle as well as the volume and cross-sectional area of the obturator externus muscle. RESULTS: The patients were assigned to 3 groups in accordance with their MRI results. Group 1 patients (n = 18) showed no contact between the obturator externus and the acetabulum. Group 2 (n = 13) showed contact, and group 3 (n = 9) an additional clear displacement of the muscle in its course. It was not possible to establish a connection between the imaging findings, the HHS, the VAS, and patient satisfaction. What was striking, however, was a significant difference between the median inclination angle in group 1 (40 degrees +/- 5.4 degrees ) and group 3 (49 degrees +/- 4.7 degrees ) (p < 0.05), and the corresponding image-morphological pathology. The average inclination angle in group 2 was 43.3 degrees +/- 3.8 degrees CONCLUSION: Contact between the obturator externus muscle and the caudal acetabula border occurs frequently, but is only rarely accompanied by a painful muscular impingement. The position of the acetabula must be seen as one of the main risk factors for contact between the acetabula border and the obturator. The hip replacement process must provide for sufficient osseous coverage of the caudal acetabula border. Furthermore, the retention of the transverse ligament may serve as protective cover for the incisura acetabuli.

Evidence of reduced muscle trauma through a minimally invasive anterolateral approach by means of MRI.

BACKGROUND: Minimally invasive techniques in THA are intended to minimize periarticular muscle trauma. The lateral approach has a risk of partial gluteal insufficiency, while the anterolateral approach carries the risk of damaging the tensor fasciae latae through intermuscular nerve and compression injury. QUESTIONS/PURPOSES: We assessed the surgical influence of the anterolateral minimally invasive approach and the modified direct lateral approach on the tensor fasciae latae and gluteus medius. METHODS: We prospectively randomized 44 patients with primary coxarthrosis to receive a cementless THA via the anterolateral minimally invasive approach or the modified direct lateral approach. We performed clinical and MRI examinations preoperatively and 3 and 12 months postoperatively, including Harris hip and pain scores. MRI analysis included assessment of the tensor fasciae latae and gluteus medius with regard to fatty atrophy and changes in the muscle cross-sectional area. RESULTS: Clinical scores were similar in the two groups but a low-grade Trendelenburg sign was observed more frequently in the lateral group. MRI showed a pronounced, postoperative fatty atrophy of the anterior part of the gluteus medius more often; and a compensatory hypertrophy of the tensor fasciae latae occurred. Higher-grade atrophy of the tensor fasciae latae and gluteus medius did not occur with the anterolateral approach. CONCLUSIONS: We found no increased damage to the tensor fasciae latae with the anterolateral approach. The lateral approach was associated with increased partial gluteus atrophy and a compensatory hypertrophy of the tensor fasciae latae. Based on fewer structural changes in the musculature, we recommend the anterolateral minimally invasive approach.

MRI findings of gluteus minimus muscle damage in primary total hip arthroplasty and the influence on clinical outcome.

INTRODUCTION: The influence of surgical trauma on gluteus minimus muscle in total hip arthroplasty (THA) and the impact on functional outcome has been hardly investigated up to now. Potential risks of minimus damage during the approach or femoral preparation is due to its attachment to the anterior facet of the greater trochanter. Possible trauma-associated functional deficits of minimus muscle may result in reduced abduction force or in an unstable hip joint. The aim of the present study was to assess the pre- and post-operative gluteus minimus muscle (tendon defects and fatty atrophy) in patient with anterolateral minimally invasive and modified lateral approach by means of magnetic resonance imaging (MRI) and to investigate the associated impact on functional outcome. MATERIALS AND METHODS: Thirty-eight patients [average age, 64 years (35-80); BMI, 28 kg/m(2) (19-35)] with primary coxarthrosis were prospectively enrolled in the study. A cementless hip prosthesis was implanted either via a minimally invasive anterolateral or a modified direct lateral approach. Patients were clinically and radiologically (MRI) examined preoperatively, 3, and 12 months postoperatively. Additionally, the Harris hip score, a pain score (NRS 0-10) and a satisfaction score (1-6) were recorded. To test the function of the abductor muscles the Trendelenburg's sign and the abductor muscle strength were evaluated. MRI evaluation includes the assessment of tendon defects and fatty atrophy of the minimus muscle. RESULTS: Tendon defects and fatty atrophy were seen in nearly 50% of the patients after THA. Harris hip-, pain-, and satisfaction scores did not correlate with the MR findings. There was also no impact on the abduction strength or the Trendelenburg's sign. Furthermore, the frequency of minimus damage was neither influenced by age, gender, BMI nor by the applied approach. CONCLUSION: Muscle atrophy and tendon defects of the minimus muscle appear frequently after THA without any favored relation to the lateral or anterolateral approach. The extent of injured minimus muscle has a minor impact on the clinical outcome particularly not on the abduction strength within the first postoperative year. The main function of the gluteus minimus is rather the centralization of the femoral head in the joint during the gait cycle than hip abduction and stabilization of the pelvis. The use of a straight stem with the associated need for lateral femoral preparation may be a risk factor for minimus tendon damage. Therefore, the surgeon should pay special attention to the prevention of surgical trauma to the gluteus minimus muscle during femoral preparation.

Comparison of multislice computed tomography with intravascular ultrasound for detection and characterization of coronary artery plaques: a systematic review.

PURPOSE: Multislice computed tomography (MSCT) is a novel non-invasive test for detection and analysis of coronary artery plaques. A systematic review was conducted of the literature to compare MSCT with IVUS as the reference standard for assessing coronary artery plaques. MATERIALS AND METHODS: We performed a literature search in the online database MEDLINE, which was accessed at http://www.pubmed.gov on 9th April 2008. RESULTS: The search identified 14 studies with 340 patients (mean age 59+/-5 years). The systematic review revealed a sensitivity of MSCT on the lesion level (n=1779 coronary plaques) on the order of 90% (range from 87 to 92%) in comparison to IVUS. Per-segment analysis (n=356) yielded a lower sensitivity of 81-86%. In the per-vessel analysis (n=90), MSCT had a better sensitivity and specificity for the RCA (83-89% and 92-100%) and the LAD (83-87% and 93%) than for the LCX (71-85% and 77-89%), and on the vessel level and the cross-section analysis MSCT was more sensitive for calcified plaques than for non-calcified plaque. It is noteworthy that most studies provide only incomplete data on technical and methodological parameters such as radiation exposure and patient characteristics. CONCLUSION: MSCT is an accurate and reliable test for detection of coronary artery plaques in comparison to IVUS with limitations in regards to the LCX and non-calcified plaques. Studies published thus far are limited by the sample sizes and methodological quality issues.