Nonoperated Hips Research Articles

Long-term course of developmental dysplasia of the hip: follow-up of the non-operated hips of patients undergoing unilateral rotational acetabular osteotomy for twenty-four years.

To follow-up the non-operated hips of patients who underwent unilateral rotational acetabular osteotomy (RAO) for bilateral developmental dysplasia of the hip (DDH) for a minimum of 20years to clarify (1) the timing of onset of hip osteoarthritis (OA) in DDH, and (2) factors associated with the development of OA. This study included 92 non-operated hips of patients who underwent unilateral RAO for bilateral DDH. We examined the timing of OA onset and total hip arthroplasty (THA) and the joint survival rate in the studied hips. Furthermore, the patients were divided into those with OA onset (progression group) and those without OA onset and compared in terms of lateral center-edge angle (LCEA), sharp angle, acetabular head index (AHI), acetabular roof obliquity (ARO), joint congruity, and the presence or absence of OA progression on the RAO side. The progression group experienced OA onset 12years after RAO and underwent THA 6years after OA onset. The 20-year joint survival rate was 73% with the endpoint of OA onset and 81% with the endpoint of THA. The progression group had significantly smaller LCEA and AHI and larger ARO. The risk of developing OA was 8.2 times greater in patients with LCEA ≤ 7° than in those with LCEA > 7°. The patients with OA progression group experienced OA onset at an average age of 55years. A small LCEA (≤ 7°) was identified as a risk factor for the development of OA.

Femoroacetabular Impingement and the Effect of Osteochondroplasty on Hip Osteoarthritis Prevention: The Pandora's Box Opening Process.

This study was conducted to assess the effect of osteochondroplasty on osteoarthritis (OA) prevention, comparing radiological evolution between identical hips from the same patient who had undergone unilateral surgery. We retrospectively reviewed radiological evolution between hips with similar shape from the same patient who had undergone unilateral surgery. In all, 56 FAI patients (112 hips) with a mean age of 42.18 ± 9.16 years and had undergone unilateral arthroscopy treatment have been included. Four independent researchers measured Wiberg, Acetabular and Alpha angles, Extrusion index, and Tönnis classification preoperatively to verify that operated and non-operated hips had the same shape. OA evolution was assessed by joint space width (JSW) in 3 different articular points and Tönnis classification. No preoperative anatomical differences were present between groups (P > 0.05). At the end of follow-up (31.9 months), a decrease of JSW in the 3 points measured was found in OP hips (OP vs. N-OP; P < 0.01). These results were correlated with changes in the proportion of patients who progressed to grade III in Tönnis classification (from 1.3% preoperative to 23.2% at the end of follow-up). Osteochondroplasty and labrum procedures were not associated with OA prevention. The OP hips showed a faster OA degeneration, which was not seen in the N-OP. These results will encourage hip surgeons to perform further investigations to avoid the "Pandora's Box Opening Process."

Do Different Approaches Make a Difference in Isokinetic Performance in Elderly Patients With Femoral Neck Fracture Who Underwent Bipolar Endoprosthesis?

Background There are ongoing doubts about the effects of the commonly used anterolateral approach (ALA) and posterolateral approach (PLA) for bipolar hemiarthroplasty (BHA) on hip muscle strength after surgery. In this study, it was aimed to evaluate the isokinetic performance of the operated and non-operated hips in patients with femoral neck fractures who underwent BHA with PLA or ALA and to compare the isokinetic performance of the hips and functional results between the two approaches. Materials and methods Forty-one patients who underwent unilateral BHA with PLA or ALA for femoral neck fracture between February 2019 and December 2020 were enrolled. The isokinetic performance of the flexor, extensor, and abductor muscles of the operated and non-operated hips were evaluated by measuring peak torque, total work, and average power. Functional status was assessed using Harris Hip Score and Short Form 36. Results The patients were divided into two groups; those operated with PLA (n=22) and with ALA (n=19). The groups had similar demographic and clinical characteristics. All isokinetic parameters of the operated hips did not differ between the groups (all p>0.05). In both groups, all isokinetic parameters were significantly lower in the operated hips than in the non-operated hips. Conclusion Although there are debates about potential extensor muscle injury with PLA and potential abductor muscle injury with ALA, this study showed that functional results and the isokinetic performance of both approaches were not different.

How does former Salter innominate osteotomy in patients with Legg-Calvé-Perthes disease influence acetabular orientation? An MRI-based study.

ABSTRACTSalter innominate osteotomy (SIO) has been successfully used in the treatment of Legg–Calvé–Perthes disease (LCPD). Recent studies that have raised concerns about acetabular retroversion after SIO have been based on plain radiographs. In order to assess the true acetabular orientation, the present study uses a specific magnetic resonance imaging (MRI) technique. In addition, the association between acetabular morphology and clinical function as well as health-related quality of life was assessed. Twenty-three patients with 24 operated hips who underwent SIO for LCPD between January 2004 and November 2014 were included. Mean age was 8.5 ± 2.2 years at surgery and 18.5 ± 2.9 years at follow-up. MRIs were conducted at 1.5 T using radial sequences. The analysis included the acetabular version, acetabular sector angles (ASAs) and alpha angles. Plain radiographs were used in order to obtain the Stulberg classification. Patient-related outcome measures included the international Hip Outcome Tool and Euroqol-5 dimensions scores. In comparison to the non-operated side, the MRI of previously operated hips showed no difference of version at the center of the femoral head but significantly decreased version just below the roof level. As a marker for posterior acetabular coverage, the ASAs between 9 and 11 o’clock were significantly decreased when compared with non-operated hips. In hips with a mild acetabular retroversion (<15°), the function was significantly decreased when compared with non-retroverted hips. The SIO is an effective tool in order to restore acetabular containment in LCPD. When compared with the non-operated hips, our collective displays only moderate changes of acetabular orientation and coverage.

MRI-based assessment of acetabular version and coverage after previous Pemberton osteotomy in skeletally mature patients.

PurposeIn hip dysplasia the Pemberton osteotomy can modify the shape of the acetabulum and is indicated for children aged between two and 12 when the triradiate cartilage is still open. However, there have been concerns about acetabular retroversion following this type of osteotomy. The studies, however, have been based on plain radiographs. The aim of our investigation was to assess the 3D acetabular orientation in patients with previous Pemberton osteotomy after skeletal maturation.MethodsTen patients with 12 operated hips were included who received Pemberton osteotomy for hip dysplasia between January 3, 2005 and March 25, 2011. Mean age at surgery and at follow-up were 7.2 years (sd 3.7) and 19.2 years (sd 3.7), respectively. MRIs were conducted with 1.5 T. Besides the measurement of acetabular version, the analysis included alpha angles, acetabular sector angles (ASAs) as well as modified ASAs (cartilage covered area angles). Furthermore, the presence of osteoarthritis (OA) as well as acetabular retroversion was determined on plain radiographs. Patient-related outcome measures included the international Hip Outcome Tool (iHOT) and EuroQol-5-Dimensions (EQ5D) scores.ResultsIn comparison with the contralateral native and healthy hips the operated hips showed similar version (19.5° (sd 4.6°) versus 18.6° (sd 7.0°); p = 0.974). Also, there were no differences in terms of femoral head sphericity (alpha angles) and acetabular coverage (ASA angles). Five of 12 Pemberton hips showed signs of beginning OA (Kellgren-Lawrence classification I or II) while none of the non-operated hips did. Patients who received surgery before the age of six years had similar functional and radiological results when compared with patients who were older than six years at surgery. Among all patients, iHOT was 91.9 (sd 10.0) and EQ5D was 90.3 (sd 7.3)).ConclusionThe Pemberton osteotomy provides good long-term radiographic and functional results without compromising acetabular version or coverage.Level of EvidenceLevel III: retrospective comparative study

Is there a significant decrease in the femoral cortical bone around Furlong® stems after 18years of follow-up?

In the context of total hip arthroplasty (THA), there are several reasons that have motivated the development of short stems. It has been postulated that short stems allow a better conservation of the bone stock if compared to conventional stems. As far as we have knowledge, the quantitative loss of diaphyseal bone stock in patients with standard femoral stems has not been fully described. The aim of this study was to provide evidences about the thickness of the cortical bone at the diaphysis in patients who have undergone unilateral THA with Furlong® stems with a minimum follow-up of 18years. A retrospective study of patients who underwent THA in a single hospital was performed. The inclusion criteria were patients who had undergone a non-cemented elective THA with a Furlong® stem, minimum follow-up of 18years, and contralateral femur and hip without history of previous surgical procedures. The follow-up analysis was performed by means of radiological examinations performed at the last follow-up visit. Data related to the sex, age at surgery and adverse events registered during the follow-up were gathered. The cortical thickness index (CTI) and cortical thickness (CT) assessed at the last follow-up visit in anteroposterior pelvic X-rays were analyzed, both in the operated hip and in the non-operated hip (which was used as control). Calibration of the measurements was done by means of using the circumference of the head of the THA. The total number of patients who met the inclusion criteria was 22. There were 14 women and eight men. There were 12 left hips. The mean age at the time of surgery was 59.32 ± 6.83 (range 50-70) years. The mean follow-up was 20.86 ± 1.90 (range 18-24) years. The CTI was found to be 11.93% greater in the non-operated hips. The CT measured at 3cm and 6cm from lesser trochanter, and at 9cm from the greater trochanter, was found to be 21.64%, 15.33% and 18.73% greater in the non-operated hips, respectively. After a minimum of 18years from the implantation of a Furlong® stem, the bone density that surrounds the implant seems to involve a cortical bone ten percent less thick than the cortical bone of the non-operated contralateral side. With this stem, the cortical zones with less CT seem to be the lateral cortex at 9cm from the greater trochanter, and the medial cortex at 3 and 6cm from the lesser trochanter. III, retrospective case-control study.

Hip Function 6 to 10 Months After Arthroscopic Surgery: A Cross-sectional Comparison of Subjective and Objective Hip Function, Including Performance-Based Measures, in Patients Versus Controls

Background:Little is known about hip-related function, mobility, and performance in patients after hip arthroscopic surgery (HA) during the time that return to sports can be expected.Purpose:To evaluate measures of subjective and objective hip function 6 to 10 months after HA in patients compared with healthy controls and to compare objective function in the HA group between the operated and nonoperated hips.Study Design:Cross-sectional study; Level of evidence, 3.Methods:A total of 33 patients who had undergone HA (mean, 8.1 ± 2.6 months postoperatively) and 33 healthy participants matched on sex, age, and activity level were compared regarding subjective hip function (Copenhagen Hip and Groin Outcome Score [HAGOS]) and objective function including hip range of motion (ROM; flexion, internal rotation, and external rotation), isometric hip muscle strength (adduction, abduction, flexion, internal rotation, and external rotation), and performance-based measures: the Y Balance Test (YBT), medial and lateral triple-hop test, and Illinois agility test. Group differences were analyzed using independent-samples t tests. Paired-samples t tests were used for a comparison of the operated and nonoperated hips. Standard effect sizes (Cohen d) were provided for all outcomes.Results:The HA group reported worse subjective hip function than the control group (HAGOS subscores: d = –0.7 to –2.1; P ≤ .004). Objective measures of hip ROM (d = –0.5 to –1.1; P ≤ .048), hip flexion strength (d = –0.5; P = .043), and posteromedial reach of the YBT (d = –0.5; P = .043) were also reduced in the HA group, although there were no significant differences between groups regarding the remaining objective measures (d = –0.1 to –0.4; P ≥ .102 to .534). The only significant difference between the operated and nonoperated hips in the HA group was reduced passive hip flexion (d = –0.4; P = .045).Conclusion:Patients who had undergone HA demonstrated reduced subjective hip function compared with controls 6 to 10 months after surgery, when return to sports can be expected. While most objective strength and performance test results were comparable between the HA and control groups at 6 to 10 months after surgery, the HA group presented with impairments related to hip mobility and hip flexion strength. No consistent pattern of impairments was found in operated hips compared with nonoperated hips.

Assessment of hip abductors by MRI after total hip arthroplasty and effect of fatty atrophy on functional outcome

ObjectivesThe aim of this study was to evaluate how fatty atrophy (FA) of the hip abductors in operated and non-operated hips affected the functional outcome following arthroplasty. MethodsForty-four hips of 22 patients (8 males and 14 females; mean age: 60 ± 14.4 (range: 24–84)) who matched the inclusion criteria and willing to participate in the study were retrospectively evaluated. The mean follow-up was 13.8 ± 2.3 (range: 10–18) months Magnetic resonance imaging (MRI) and Harris Hip Score (HHS) were used to evaluate muscle degeneration and functional outcome after unilateral THA through a posterolateral approach. The FA grade was evaluated using Goutallier grading system. Non-operated hips of subjects were used as the control. Age, duration after the operation, gluteal muscle FA, and the relationships with HHS were evaluated. ResultsFA was more evident in the operated hip (p < 0.05), and was more in the gluteus minimus than in the gluteus medius in both hips (p < 0.05). Patients' age was not correlated with gluteal muscle FA in the operated hip (p > 0.05), whereas there was a positive correlation with the contra-lateral hip (p < 0.05). Duration after surgery did not affect gluteal muscle FA in the operated hip. Older age and FA of either the operated or healthy hip resulted in poorer HHS (p < 0.05). HHS had the strongest correlations with patient age (p < 0.001) and FA (p = 0.026) of the gluteus minimus of contralateral hip. ConclusionFollowing THA, there was marked FA in the operated hip compared to that in the contralateral hip. In these cases, degree of FA in the replaced hip did not correlate with patients' age. Fatty atrophy of the gluteus minimus precedes that of gluteus medius. FA of the contralateral gluteus minimus and patient age are strongly correlated with lower HHS. Level of evidence: Level IV, diagnostic study. Level of evidenceLevel IV, diagnostic study.

The Fate of the Iliopsoas Muscle in Long-term Follow-up After Open Reduction With a Medial Approach in Developmental Dysplasia of the Hip. Part 2: Isokinetic Muscle Strength Evaluation.

The impact on long-term weakness of hip flexion of complete iliopsoas tenotomy during open reduction of developmental hip dysplasia with a medial approach has not yet been fully clarified. The purpose of this study was to investigate the isokinetic muscle strength (IMS) of hip flexor and extensor muscles in these patients and also to analyze the effect of spontaneous reattachment of the iliopsoas muscle on IMS measurements. The study included 20 patients. Earlier magnetic resonance imaging examination of all the patients revealed spontaneous reattachment of the iliopsoas in 18 (90%) patients. IMS measurements were performed at 60 and 150 degrees/s. The peak torque, total work (TW), average power (AP), work fatigue, and agonist to antagonist muscle ratio of the operated and nonoperated hips were recorded separately for flexors and extensors. The effect of iliopsoas reattachment on IMS was also evaluated. The mean follow-up period was 16.65±2.16 (13 to 20) years. Total work (P=0.013) and average power (P=0.009) of the flexor muscles and work fatigue of the extensor muscles (P=0.030) of the operated hip were significantly decreased when compared with the nonoperated hips at 150 degrees/s. There was no significant difference between the flexor muscles of the operated and nonoperated hips (P<0.05) at 60 degrees/s and extensor muscles (P<0.05) at 150 degrees/s. In addition, patients without reattachment had lower IMS in the operated hips. Flexor muscle strength was decreased in the operated hip against low resistance in long-term follow-up after iliopsoas tenotomy. This may reflect that hip muscle strength was decreased after prolonged activities such as sports. However, in forceful activities flexor muscle strength was retained due to iliopsoas reattachment. On the basis of this study we thought that spontaneous reattachment of the iliopsoas tendon substantially preserves muscle strength. Nonetheless possible efforts should be made to surgically reattach the psoas tendon to preserve strength of the muscle. Therapeutic level IV.

Retrospective Analysis of Idiopathic Hip Osteoarthritis Based on Anteroposterior Pelvic Radiograph; Hip Osteoarthritis Caused by Femoroacetabular Impingement

Background: Femoroacetabular Impingement (FAI) means pathological impact between the femoral head-neck junction and the acetabular rim. Objectives: The aim of this retrospective study was to analyze Femoroacetabular Impingement (FAI) signs, which can lead to idiopathic hip osteoarthritis, from preoperative radiographs of patients indicated for total hip replacement as compared to radiographs of patients without this indication. Methods: We examined the preoperative anteroposterior (AP) pelvic radiograph, the pincer and cam FAI signs of patients between 45 and 60 years, who had undergone total hip replacement. We examined in the same group, the operated side and the non-operated hips with osteoarthritis (patients group). In the control group we examined the pelvic radiograph of patients without symptoms between 45 and 60 years old (control, group). Results: In the patient group (215 patients, 313 hips) we noted the signs of FAI in 88% while in the control group (112 patients 224 hips) these signs were found in 8.8% of cases. Conclusions: In 88% of primary osteoarthritis cases we found FAI morphology on the AP pelvic radiograph, similarly to those found in the bibliography, and we considered naming primary osteoarthritis, secondary osteoarthritis caused by FAI. In the majority of cases, early diagnosis with simple, cheap and easily accessible AP pelvic radiograph with low dose of radiationmay also be warranted

Acetabular changes associated with avascularnecrosis of the femoral head in a piglet model.

ObjectivesAn experimental piglet model induces avascular necrosis (AVN) and deformation of the femoral head but its secondary effects on the developing acetabulum have not been studied. The aim of this study was to assess the development of secondary acetabular deformation following femoral head ischemia.MethodsIntracapsular circumferential ligation at the base of the femoral neck and sectioning of the ligamentum teres were performed in three week old piglets. MRI was then used for qualitative and quantitative studies of the acetabula in operated and non-operated hips in eight piglets from 48 hours to eight weeks post-surgery. Specimen photographs and histological sections of the acetabula were done at the end of the study. ResultsThe operated-side acetabula were wider, shallower and misshapen, with flattened labral edges. At eight weeks, increased acetabular cartilage thickness characterised the operated sides compared with non-operated sides (p < 0.001, ANOVA). The mean acetabular width on the operated side was increased (p = 0.015) while acetabular depth was decreased anteriorly (p = 0.007) and posteriorly (p = 0.44). The cartilage was thicker, with delayed acetabular bone formation, and showed increased vascularisation with fibrosis laterally and focal degenerative changes involving chondrocyte hypocellularity, chondrocyte cloning, peripheral pannus formation and surface fibrillation. ConclusionsWe demonstrate that femoral head AVN in the young growing piglet also induced, and was coupled with, secondary malformation in acetabular shape affecting both articular and adjacent pelvic cartilage structure, and acetabular bone. The femoral head model inducing AVN can also be applied to studies of acetabular maldevelopment, which is less well understood in terms of developing hip malformation.Cite this article: Bone Joint Res 2014;3:130–8.

Correlative Analysis of MRI-evident Abductor Hip Muscle Degeneration and Power After Minimally Invasive Versus Conventional Unilateral Cementless THA

The 2 main null hypotheses of this study were: (1) the 4-year surgical trauma-related degeneration within the hip abductor muscles after a minimally invasive approach to total hip arthroplasty would be similar to that following a conventional approach; and (2) no differences in perioperative blood loss or postoperative hip pain would be observed between the minimally invasive and conventional approaches.In 40 consecutive randomly selected adult patients with unilateral primary hip osteoarthritis, a cementless Zweymüller-Plus THA (Smith & Nephew Orthopaedics, Baar, Switzerland) was implanted by a single surgeon in 1 institution during the same period. Twenty patients underwent a minimally invasive approach (group A), and 20 patients underwent a conventional anterolateral approach (group B). Four years postoperatively, the operated and contralateral nonoperated hips of 37 available patients from both groups were examined with magnetic resonance imaging to show any changes in the gluteus medius and tensor fascia latae. Simultaneously, hip abductor power was measured bilaterally in both groups. Anthropometric data, blood loss, Short Form 36 self-assessment questionnaire, visual analog pain score, and walking distance were also analyzed.The reliability of magnetic resonance imaging and hip abductor power measurements was high. No difference was found in hip abductor power on the operated side between the 2 groups, whereas hip abductor power on the nonoperated side was significantly higher in both groups. This study revealed no mechanical and functional benefits in favor of patients undergoing minimally invasive vs conventional total hip arthroplasty.

Periprosthetic Bone Turnover after Primary Total Hip Arthroplasty Measured by Single-Photon Emission Computed Tomography

Alterations in periprosthetic bone are common sequlae of prosthetic implants.This prospective 3-year study was performed to follow regional periprosthetic bone turnover after uncomplicated total hip arthroplasty (THA) using single-photon emission computed tomography (SPECT). Eighteen patients (nine men, nine women: mean age 61 years, range from 50 to 73 years) with primary hip osteoarthritis underwent either uncemented or cemented THA. The SPECT measurements were taken 6, 12, and 36 months after THA. Bone mineral density (BMD) measurements were performed on the patients during follow-up. The mean SPECT uptake ratios decreased significantly in the regions of interest (ROIs) during follow-up compared to baseline value, in the trochanter major (p = 0.006), the trochanter minor (p = 0.009) and the total area (p = 0.018). Despite these decreases the uptake ratios in the medial cortex (p = 0.014), tip (p = 0.002) and total area (p = 0.016) remained significantly higher in the operated side than in the contralateral side (non-operated) 3 years after THA. Changes in bone turnover in the vicinity of the implant did not correlate with changes in periprosthetic BMD. Local periprosthetic bone turnover decreased slowly after THA and did not recover to the level typical of non-operated hips. This led us to suggest that bone turnover around the femoral implants remains increased more than 3 years after THA even if there are no signs of failure of the prosthesis.

What happens to femoral neck bone mineral density after hip resurfacing surgery?

The major advantage of hip resurfacing is the decreased amount of bone resection compared with a standard total hip replacement. Fracture of the femoral neck is the most common early complication and poor bone quality is a major risk factor. We undertook a prospective consecutive case control study examining the effect of bone mineral density changes in patients undergoing hip resurfacing surgery. A total of 423 patients were recruited with a mean age of 54 years (24 to 87). Recruitment for this study was dependent on pre-operative bilateral femoral bone mineral density results not being osteoporotic. The operated and non-operated hips were assessed. Bone mineral density studies were repeated over a two-year period. The results showed no significant deterioration in the bone mineral density in the superolateral region in the femoral neck, during that period. These findings were in the presence of a markedly increased level of physical activity, as measured by the short-form 36 health survey physical function score.

The Evaluation of Hip Muscles in Patients Treated With One-stage Combined Procedure for Unilateral Developmental Dysplasia of the Hip: Part II: Isokinetic Muscle Strength Evaluation

To assess the isokinetic muscle strength (IMS) of hip flexor and extensor muscles in patients treated with one-stage combined procedure for developmental dysplasia of the hip and analyze the effect of the status of hip muscles on IMS. Twenty-two patients were included in the study. The mean age was 154.4+/-34.6 (110-216) months and the mean follow-up was 112.6+/-32.0 (68-159) months. All patients underwent complete tenotomy of the iliopsoas muscle to ease open reduction and had excellent results according to the modified McKay criteria of Barrett and type I hips according to the radiologic criteria of Severin. All patients had earlier magnetic resonance imaging examination that revealed reattachment of the iliopsoas in 7 (32%) patients. IMS measurements were performed at 120 degrees/s and 240 degrees/s. The peak torque (PT), PT angle, total work (TW), and average power (AP) values of operated and nonoperated hips were recorded separately for flexors and extensors. For flexors, TW and AP values were lower at the operated hip when compared with the nonoperated hip at both angular velocities. PT was only lower at the operated hip at 120 degrees/s. For extensor muscles, PT, TW, AP, and PT angle showed no statistically significant difference at either angular velocity. For flexors, the PT deficit between the operated and nonoperated hips at 120 degrees/s and 240 degrees/s was measured as 15.3% and 8.0%, respectively. There was no difference between the flexor muscles of operated and nonoperated hips considering PT, TW, and AP at both angular velocities in patients with reattachment. The IMS deficit of flexor muscles at 120 degrees/s was significantly higher in patients without reattachment of iliopsoas when compared with those with reattachment, and correlated to the widths of the iliopsoas muscle at levels II and III. Assessing the results of surgical treatment of DDH with conventional radiologic and functional criteria might be misleading in some patients with excellent results because some of these patients, particularly those without reattachment of the iliopsoas muscle, experience significant weakness in hip flexion.

Developmental dysplasia of the hip: Is acetabular retroversion a crucial factor?

The objective of this study was to investigate a possible relation between congenital hip dysplasia and acetabular retroversion and to explore the eventual influence of the latter in the surgical decision for periacetabular osteotomy. We assessed the classical morphological characteristics of both hips, with an additional newly described retroversion index. The study was conducted in 174 patients with uni- or bilateral congenital hip dysplasia having undergone unilateral (153 patients) or bilateral (21 patients) periacetabular osteotomy when respectively one or both dysplastic hips remained symptomatic. In the group of operated hips (195 hips in total), 53% of the acetabuli were anteverted, 42% retroverted, and 5% neutral orientations. The group of nonoperated hips (153 hips) included 24% normal hips, 22% hips with normal coverage but retroverted, 35% dysplastic hips with anteverted or neutral orientation, and 19% dysplastic retroverted hips. Comparing the two hips in the subgroup of patients in whom the operated and nonoperated sides were both dysplastic failed to demonstrate statistically significant difference in the mean retroversion index. However, all the other variables measured were significantly different; with the operated side more dysplastic. Comparing the two hips in the other subgroups showed that acetabular retroversion was nearly always bilateral and symmetrical, even in presence of unilateral congenital dysplasia. Our data suggest that the presence of acetabular retroversion is probably independent of the congenital hip dysplasia and that this abnormality seems at best a secondary factor in the appearance of dysplastic hip symptoms. Level IV, retrospective diagnostic study.

To what extent does leg length discrepancy impair motor activity in patients after total hip arthroplasty?

The aim of this study was to evaluate the effects of limb lengthening up to 20 mm after THA on symmetry of hip kinematics and kinetics during common activities of daily living. Twenty patients (age range 49-80 years) operated on with Link Lubinus II THA, with lateral access and a mean follow-up of 16 months, were assessed by gait analysis during level walking, stair ascending and descending. The time-distance, hip kinetics and kinematics values were statistically compared between the operated side and the non-operated side in order to assess symmetry. The 12-item Questionnaire was used to assess satisfaction and personal perception of limb lengthening. Mean value of limb lengthening after THA was 11 mm (SD 6). Minor abnormalities were found in the kinematics and kinetics of the operated and non-operated hips during level walking and stair climbing. The score of the questionnaire corresponded to a high level of satisfaction after THA and only two patients complained of limping independent from the amount of discrepancy. From this study we can conclude that a leg length inequality in the range of 1-20 mm does not impair the symmetry of time-distance parameters and of hip kinematics and kinetics during gait and stairs walking. Although objective, gait analysis data did not correspond to patient's perception of discrepancy, which is subjective and irrespective of the amount of lengthening. There is biomechanical evidence that a limb lengthening of up to two centimetres after THA in general does not need to be corrected by means of a contralateral shoe lift. Individual decisions to the contrary need to be justified.

Isometric performance following total hip arthroplasty and rehabilitation

We compared differences in isometric strength between older adults who have undergone elective unilateral total hip arthroplasty (THA) and completed rehabilitation with a population of community-dwelling older adults who have not had THA. The study was a cross-sectional design, and 22 unilateral THA subjects and 38 community-dwelling older adults participated. THA subjects received on average 13 outpatient or home-based physical therapy sessions before evaluation. THA subjects were evaluated 4 to 5 months postsurgery. We assessed isometric muscle strength by measuring peak hip torque per body weight with a robotic dynamometer during abduction, flexion, and extension. No significant performance differences were observed between operated and nonoperated hips of THA subjects. THA subject operated and nonoperated hips generated significantly less peak torque per body weight during flexion (p = 0.03) compared with community-dwelling older adult hips (THA subject operated hips = 6.96 ft-lb/lb, THA subject nonoperated hips = 8.26 ft-lb/lb, community-dwelling older adult hips = 11.56 ft-lb/lb). No significant differences were observed between THA subjects and community-dwelling older adults during hip extension (p = 0.55) or abduction (p = 0.17). At 4 to 5 months postsurgery, THA subjects were not at the same level of biomechanical performance as community-dwelling older adults. Significant strength deficits were found in THA subject operated versus nonoperated hips during isometric flexion. Additional or modified physical therapy that targets the hip flexors is recommended after THA.

Natural course of the minimally symptomatic nonoperated hip in patients with bilateral hip dysplasia treated with contralateral rotational acetabular osteotomy

BackgroundThe purpose of this study was to investigate the natural course of the minimally symptomatic nonoperated hip in patients with preosteoarthritis or early osteoarthritis in bilaterally dysplastic hips. MethodsThe material consisted of 61 patients with bilaterally dysplastic hips who underwent rotational acetabular osteotomy in their symptomatic hip and nonoperative treatment in their asymptomatic or minimally symptomatic hip. The average follow-up was 10.1 years (range 7.0–15.6 years), and the average age at the time of surgery was 38.2 years (range 20–58 years). All patients were divided into two groups by joint congruity of the nonoperated hip at surgery with rotational acetabular osteotomy. ResultsOn radiographic assessment, 1 of the 35 preosteoarthritis hips had developed early osteoarthritis, and 6 of the 26 early osteoarthritis hips had progressed to advanced osteoarthritis. The Kaplan-Meier survivorship analysis for the whole group of nonoperated hips, with radiographic progression of osteoarthritis as the endpoint, predicted a 10-year survival rate of 83.7% (95% confidence interval 70%–98%). Significant differences were observed in the radiographic stage (pre- and early osteoarthritis group, P=0.015) and joint congruity (good and fair group, P=0.005). ConclusionsIf the contralateral nonoperated hip has good joint congruity, minimal symptoms, and no or little radiographic change in patients with pre- or early osteoarthritis and bilateral acetabular dysplasia, the probability of radiographic progression is low.

Preservation of Bone Mineral Density of the Proximal Femur Following Hemisurface Arthroplasty

Bone mineral density of the proximal femur was measured in six patients who underwent hemisurface replacement for osteonecrosis of the femoral head. Bone mineral density values in operated and contralateral nonoperated hips were compared. In four patients who had sequential examinations, bone mineral density was compared over time. Average patient age was 34.6 years, average follow-up was 9.1 years, and mean follow-up of bone mineral density measurements was 6.6 years. Average bone mineral density variation was 0.0048 to -0.0264 g/cm2 per year in all five regions in nonoperated hips and -0.012 to -0.0300 g/cm2 in operated hips. These results support bone conservation and preservation with hemiresurfacing arthroplasty in young patients with osteonecrosis of the femoral head.