Clinical Orthopaedics and Related Research ®

A Publication of The Association of Bone and Joint Surgeons ®

Symposium: Papers Presented at the Annual Closed Meeting of the International Hip Society 22 articles

Articles

Long-term Experience with Chiari’s Osteotomy

Rainer Kotz MD, Catharina Chiari MD, Jochen G. Hofstaetter MD, Andreas Lunzer MD, Philipp Peloschek MD Fifty-six years after the introduction of Chiari’s pelvic osteotomy, we report the long-term function scores and radiographic grade of osteoarthritis in 66 patients with 80 pelvic osteotomies with a minimum followup time of 27 years (average, 32 years; range, 27–48 years). These 66 patients were those who could be contacted and who returned for a followup visit from among 450 patients operated between 1961 and 1981. Thirty-two hips (40%) in 28 patients had undergone a total joint arthroplasty after an average 26 years (range, 13–41 years). Forty-eight hips in 41 patients (60%) were not replaced, their Harris hip score being a median of 82 points (range, 37–100 points). For the 22 patients for whom we had complete radiographs the average preoperative CE angle was 11.6°, 48.6° (range, 31°–82.8°) immediately postoperatively, and 41.6° (range, 13.7°–90°) at last followup . Despite a functional hip score in most patients retaining their native hip, the degree of osteoarthritis progressed at last followup. We observed a similar mean age at the time of osteotomy in patients converted to total hip arthroplasty and those retaining their native hip. Age at time of surgery was inversely correlated (r = −0.78) with the interval between the osteotomy and THA. In this select patient group we found good functional outcome in patients who underwent Chiari pelvic osteotomy, with a conversion rate of 40% to total hip arthroplasty a mean of 32 years after the procedure.,[object Object]

Survival of the Cementless Spotorno® Stem in the Second Decade

Peter R. Aldinger MD, PhD, Alexander W. Jung MD, Steffen J. Breusch MD, PhD, Volker Ewerbeck MD, PhD, Dominik Parsch MD, PhD [object Object],[object Object]

Alumina-on-alumina Total Hip Arthroplasty in Young Patients: Diagnosis is More Important than Age

Eduardo Garcia-Rey MD, PhD, EBOT, Ana Cruz-Pardos MD, PhD, Eduardo Garcia-Cimbrelo MD, PhD

Total hip arthroplasty (THA) in young patients has a high loosening rate, due in part to acetabular deformities that may compromise bone fixation and polyethylene wear. We therefore asked whether wear or osteolysis and loosening differ in patients under 40 years of age with alumina-on-alumina THA compared to those who are older. We prospectively followed 56 patients (63 hips) younger than 40 years (Group 1) and 247 patients (274 hips) older than 40 (Group 2) who had an alumina-on-alumina THA. The minimum followup was 4 years (mean, 5.6 years; range, 4–9 years). The two groups differed in various features: there were no patients with primary osteoarthritis in Group 1 and they had worse preoperative function and range of mobility, while weight, activity level, and implant size were greater in Group 2. The survival rate for cup loosening at 80 months postsurgery was 90.8% (95% confidence interval, 82.9–98.6%) for Group 1 and 96.5% (95% confidence interval, 94.2–98.7%) for Group 2. Cup loosening was less frequent with primary osteoarthritis than with severe developmental dysplasia of the hip. Although an alumina-on-alumina THA provided similar midterm survival and radiographic loosening in both age groups, the preoperative diagnosis seems more important than age for outcome. Continued followup will be required to determine if the alumina-on-alumina bearings in young patients result less risk of osteolysis and loosening.,[object Object]

Enhanced Cell Integration to Titanium Alloy by Surface Treatment with Microarc Oxidation: A Pilot Study

Young Wook Lim MD, Soon Yong Kwon MD, Doo Hoon Sun MD, Hyoun Ee Kim PhD, Yong Sik Kim MD Microarc oxidation (MAO) is a surface treatment that provides nanoporous pits, and thick oxide layers, and incorporates calcium and phosphorus into the coating layer of titanium alloy. We presumed such modification on the surface of titanium alloy by MAO would improve the ability of cementless stems to osseointegrate. We therefore compared the in vitro ability of cells to adhere to MAOed titanium alloy to that of two different types of surface modifications: machined and grit-blasted. We performed energy-dispersive x-ray spectroscopy and scanned electron microscopy investigations to assess the structure and morphology of the surfaces. Biologic and morphologic responses to osteoblast cell lines (SaOS-2) were then examined by measuring cell proliferation, cell differentiation (alkaline phosphatase activity), and αvβ3 integrin. The cell proliferation rate, alkaline phosphatase activity, and cell adhesion in the MAO group increased in comparison to those in the machined and grit-blasted groups. The osteoblast cell lines of the MAO group were also homogeneously spread on the surface, strongly adhered, and well differentiated when compared to the other groups. This method could be a reasonable option for treating the surfaces of titanium alloy for better osseointegration.

Protrusio Acetabuli: New Insights and Experience with Joint Preservation

Michael Leunig MD, Shane J. Nho MD, MS, Luigino Turchetto MD, Reinhold Ganz MD Protrusio acetabuli is identified on anteroposterior (AP) radiographs of the pelvis with an acetabular line projecting medial to the ilioischial line. We documented this radiographic sign and additional radiographic parameters in 19 patients (29 hips) with protrusio and compared the parameters to those of 29 older patients (29 hips) with advanced primary osteoarthritis (OA) but no protrusio and 12 younger patients (22 hips) with protrusio but no advanced OA. A negative acetabular roof angle and particularly large acetabular fossa were more apparent in younger patients; these hips suggest the destruction of a protrusio hip begins less in the medial joint area and more in the posteroinferior joint, and the mechanism is driven less by excessive medially directed forces but by a pincer impingement. While the indication for joint-preserving surgery currently consists primarily of a valgus femoral osteotomy based on AP radiographs and patient age, modern decision making also relies on cartilage evaluation and requires advanced surgical techniques. We conclude joint-preservation surgery must be tailored to the individual hip morphology.,[object Object]

Accuracy of Computer-assisted Navigation for Femoral Head Resurfacing Decreases in Hips with Abnormal Anatomy

Rocco P. Pitto MD, PhD, Sharif Malak, Iain A. Anderson PhD Computer-assisted navigation systems for hip resurfacing arthroplasty are designed to minimize the chance of implant malposition. However, there is little evidence computer navigation is useful in the presence of anatomical deformity. We therefore determined the accuracy of an image-free resurfacing hip arthroplasty navigation system in the presence of a pistol grip deformity of the head and femoral neck junction and of a slipped upper femoral epiphysis deformity. We constructed an artificial phantom leg from machined aluminum with a simulated hip and knee. The frontal and lateral plane implant-shaft angles for the guide wire of the femoral component reamer were calculated with the computer navigation system and with an electronic caliper combined with micro-CT. There was a consistent disagreement between the navigation system and our measurement system in both the frontal plane and lateral plane with the pistol grip deformity. We found close agreement only for the frontal plane angle calculation in the presence of the slipped upper femoral epiphysis deformity, but calculation of femoral head size was inaccurate. The use of image-free navigation for the positioning of the femoral component appears questionable in these settings.

Role of the Extraosseus Blood Supply in Osteoarthritic Femoral Heads?

Ralf Schoeniger MD, Norman Espinosa MD, Rafael J. Sierra MD, Michael Leunig MD, Reinhold Ganz MD Blood perfusion to the femoral head might be endangered during the surgical approach or the preparation of the femoral head or both in hip resurfacing arthroplasty. The contribution of the intramedullary blood supply to the femoral head in osteoarthritis is questionable. Therefore, the contribution of the extraosseous blood supply to osteoarthritic femoral heads was measured intraoperatively to question if there is measurable blood flow between the epiphysis and metaphysis in osteoarthritic hips in case of extraosseus vessel damage. At defined points during surgery we acquired the epiphyseal and metaphyseal femoral head perfusion by high-energy laser Doppler flowmetry. Complete femoral neck osteotomy sparing the retinacular vessels to simulate intraosseous blood disruption showed unchanged epiphyseal blood flow compared to initial measurement after capsulotomy. The pulsatile signal disappeared after transection of the retinacular vessels. Based on these acute measurements, we conclude intramedullary blood vessels to the femoral head do not provide measurable blood supply to the epiphysis once the medial femoral circumflex artery or the retinacular vessels have been damaged. We recommend the use of a safe surgical approach for hip resurfacing and careful implantation of the femoral component to respect blood supply to the femoral head and neck region in hip resurfacing arthroplasty.

Intra- and Intersurgeon Variability in Image-free Navigation System for THA

Hirotsugu Ohashi MD, PhD, Masanori Matsuura MD, Yusaku Okamoto MD, PhD, Yoshiaki Okajima MD In image-free navigation systems, cup orientation is determined in the pelvic coordinate by registration of bony landmarks. While the value of navigation relates primarily to the reliability and accuracy of cup placement, the reliability of registration plays a role in cup placement. We therefore examined intra- and intersurgeon variability in registration and the distance between registration points in each bony landmark. Thirty-seven THAs were performed in the lateral position and 15 THAs in the supine position. The cup was fixed using a navigation system. The registration was repeated two more times by operator and assistant, and the intra- and intersurgeon variability of cup abduction angle and anteversion was analyzed by ICC (intraclass correlation coefficients). In 25 hips, the distance between intrasurgeon registration points and between intersurgeon registration points in each landmark were calculated. The ICC in the lateral position ranged between 0.59 and 0.81, and between 0.85 and 0.95 in the supine position. The ICCs of cup abduction angle for the intra- and intersurgeon variability were 0.92 and 0.95 for the supine position and 0.65 and 0.59 for the lateral position. Those of anteversion were 0.93, 0.85, and 0.81, 0.72, respectively. The variability in locating the ASIS in the lateral position was greater than that in the supine position. The variability of registration points depended on bony landmarks and patient position but the range of variability we found would not likely result in a large variability in cup placement.

Second-generation Extensively Porous-coated THA Stems at Minimum 10-year Followup

David W. Hennessy BS, John J. Callaghan MD, Steve S. Liu MD [object Object],[object Object]

High Cup Angle and Microseparation Increase the Wear of Hip Surface Replacements

Ian J. Leslie PhD, Sophie Williams PhD, Graham Isaac PhD, Eileen Ingham PhD, John Fisher PhD High wear rates and high patient ion levels have been associated with high (> 55°) cup inclination angles for metal-on-metal surface replacements. Wear rates and patterns have been simulated for ceramic-on-ceramic bearings by applying microseparation to replicate head offset deficiency. We tested 39-mm metal-on-metal surface replacements (n = 5) in a hip simulator with (A) an increased cup inclination angle of 60° and (B) an increased cup inclination angle and microseparation over 2 million cycles. (A) resulted in a ninefold increase in wear rate and (B) resulted in a 17-fold increase in wear rate compared to a standard gait condition study. Wear particles produced under microseparation conditions were larger than those produced under standard conditions but of similar shape (round to oval). The data suggest both head and cup position influence the wear of surface replacements; we believe it likely bearings with high wear either have a high cup inclination angle, an offset deficient head, or a combination of both.

Periacetabular Osteotomy for Acetabular Dysplasia in Patients Older than 40 Years: A Preliminary Study

Michael B. Millis MD, Michael Kain MD, Rafael Sierra MD, Robert Trousdale MD, Michael J. Taunton MD, Young-Jo Kim MD, PhD, Scott B. Rosenfeld MD, Ganesh Kamath MD, Perry Schoenecker MD, John C. Clohisy MD The functional outcomes of periacetabular osteotomy (PAO) and factors predicting outcome in the older patient with acetabular dysplasia are not well understood. We therefore retrospectively determined the functional outcome of 70 patients (87 hips) over age 40 treated with PAO in three institutions; we also determined whether preoperative factors, particularly the presence of osteoarthritis, influenced the survival of the hip or time to total hip arthroplasty after PAO. The average age at surgery was 43.6 years. The minimum followup was 2 years (mean, 4.9 years; range, 2–13 years). Twenty-one hips (24%) had undergone total hip arthroplasty (THA), at a mean of 5.2 years after PAO (range, 1.9–7.6 years). Surviving hips had a mean improvement in Harris hip score from 60.7 to 90.3 and in total WOMAC pain score from 8.7 to 3. We observed no differences in preoperative or postoperative radiographic measurements or preoperative clinical function scores (HHS, WOMAC) in hips surviving and hips having THA. The risk of THA at 5 years after PAO was 12% in hips with preoperative Tönnis Grade 0 or 1 and 27% for Tönnis Grade 2. Our preliminary study suggests that PAO will give satisfactory functional and pain scores in patients over age 40 having dysplastic hips with mild or no arthrosis.,[object Object]

Combined Periacetabular and Femoral Osteotomies for Severe Hip Deformities

John C. Clohisy MD, Lauren C. St John BS, Ryan M. Nunley MD, Amanda L. Schutz PhD, MPA, Perry L. Schoenecker MD Periacetabular osteotomy (PAO) is an effective acetabular reorientation technique for treatment of symptomatic acetabular dysplasia. In hips with severe deformities, an adjunctive femoral osteotomy (PFO) may optimize correction, joint stability, and congruency. We analyzed the clinical and radiographic results of combined PAO/PFO in treating severe hip deformities. Second, we compared the clinical results of patients treated with PAO/PFO with patients treated with isolated PAO for lesser deformities. Twenty-five patients (28 hips) treated with PAO/PFO were reviewed and followed a minimum of 16 months (mean, 44 months). The matched PAO cohort included 25 patients (28 hips). For the PAO/PFO group, the average Harris hip score improved from 60.9 to 86.3. Eighty-nine percent of the patients demonstrated at least a 10-point improvement in the hip score and 75% had a Harris hip score over 80 points. Radiographic evaluation demonstrated consistent deformity correction. The PAO/PFO group had a lower average Harris hip score preoperatively, yet hip function after surgery was comparable between groups. These data indicate combined PAO/PFO is associated with improved hip function in most patients. These clinical results are comparable to those obtained with isolated PAO for lesser hip deformities.,[object Object]

Oral Antibiotics are Effective for Highly Resistant Hip Arthroplasty Infections

José Cordero-Ampuero MD, PhD, Jaime Esteban MD, PhD, Eduardo García-Cimbrelo MD, PhD Infected arthroplasties reportedly have a lower eradication rate when caused by highly resistant and/or polymicrobial isolates and in these patients most authors recommend intravenous antibiotics. We asked whether two-stage revision with interim oral antibiotics could eradicate these infections. We prospectively followed 36 patients (mean age, 71.8 years) with late hip arthroplasty infections. Combinations of oral antibiotics were prescribed according to cultures, biofilm, and intracellular effectiveness. The minimum followup was 1 year (mean, 4.4 years; range, 1–12 years). We presumed eradication in the absence of clinical, serologic, and radiographic signs of infection. Infection was eradicated in all 13 patients with highly resistant bacteria who completed a two-stage protocol (10 with methicillin-resistant Staphylococci) and in eight of 11 patients treated with only the first stage (and six of nine with methicillin-resistant Staphylococci). Infection was eradicated in six of six patients with polymicrobial isolates (of sensitive and/or resistant bacteria) who completed a two-stage protocol and in five of seven with polymicrobial isolates treated with only the first surgery. The Harris hip score averaged 88.1 (range, 70–98) in patients who underwent reimplantation and 56.8 (range, 32–76) in patients who underwent resection arthroplasty. Long cycles of combined oral antibiotics plus a two-stage surgical exchange appear a promising alternative for infections by highly resistant bacteria, methicillin-resistant Staphylococci, and polymicrobial infections.,[object Object]

Proximal Femoral Reconstructions with Bone Impaction Grafting and Metal Mesh

Martín A. Buttaro MD, Fernando Comba MD, Francisco Piccaluga MD Extensive circumferential proximal cortical bone loss is considered by some a contraindication for impaction bone grafting in the femur. We asked whether reconstruction with a circumferential metal mesh, impacted bone allografts, and a cemented stem would lead to acceptable survival in these patients. We retrospectively reviewed 14 patients (15 hips) with severe proximal femoral bone defects (average, 12 cm long; 14 type IV and one type IIIB using the classification of Della Valle and Paprosky) reconstructed with this method. The minimum followup was 20 months (average, 43.2 months; range, 20–72 months). Preoperative Merle D’Aubigné and Postel score averaged 4.8 points. With revision of the stem as the end point, the survivorship of the implant was 100% at one year and 86.6% at 72 months. The mean functional score at last followup was 14.4 points. We observed two fractures of the metal mesh at 31 and 48 months in cases reconstructed with a stem that did not bypass the mesh. Dislocation (3 cases) and acute deep infection (3 cases) were the most frequent complications. Patients with complete absence of the proximal femur may be candidates for biological proximal femoral reconstructions using this salvage procedure. Bone impaction grafting must be a routine technique if this method is selected.,[object Object]

Ceramic-Ceramic Bearing Decreases Osteolysis: A 20-year Study versus Ceramic-Polyethylene on the Contralateral Hip

Philippe Hernigou MD, Sebastien Zilber MD, Paolo Filippini MD, Alexandre Poignard MD Although ceramic implants have been in use for many years and they are intended to minimize wear debris it is unknown whether alumina-on-alumina or alumina-on-polyethylene produce less wear and osteolysis. We therefore investigated wear and osteolysis on 28 bilateral arthroplasties (one ceramic-ceramic and the contralateral ceramic-polyethylene) of patients who had survived 20 years without revision and without loosening of either hip. Osteolysis was identified on anteroposterior pelvic radiographs and 3-D volume from CT scans. The number of osteolytic lesions detected with CT scan was higher than with radiographs. The number of lesions was higher on the side with the alumina-PE couple. With a similar length of followup on each side, the surface and the volume of osteolysis were consistently higher on the side with the alumina-PE couple. We found no correlation between the volume of osteolysis and the volume of estimated wear in each couple of friction. Hips with osteolysis had a lower Harris score.,[object Object]

Trabecular Metal™ Cups for Acetabular Defects With 50% or Less Host Bone Contact

Dror Lakstein MD, David Backstein MD, MEd, FRCSC, Oleg Safir MD, FRCSC, Yona Kosashvili MD, MHA, Allan E. Gross MD, FRCSC Acetabular component revision in the context of large contained bone defects with less than 50% host bone contact traditionally have been treated with roof reinforcement or antiprotrusio cages. Trabecular Metal™ cups (Zimmer, Inc, Warsaw, IN) may offer a reasonable treatment alternative. We evaluated the clinical and radiographic outcome of this mode of treatment. We prospectively followed 53 hip revision acetabular arthroplasty procedures performed with Trabecular Metal™ cups for contained defects with 50% or less contact with native bone. All patients were clinically and radiographically evaluated for evidence of loosening or failure. Minimum followup was 24 months (average, 45 months; range, 24–71 months). Contact with host bone ranged from 0% to 50% (average, 19%). The mean postoperative Merle d’Aubigne-Postel score was 10.6 (range, 1–12), with a mean improvement of 5.2 (range, −4–10) compared to the preoperative score. Two failed cups (4%) were revised. Two additional cups (4%) had radiographic evidence of probable loosening. Complications included four dislocations and one sciatic nerve palsy. The data suggest treatment of cavitary defects with less than 50% host bone contact using Trabecular Metal™ cups, without structural support by augments or structural bone grafts, is a reasonable option.,[object Object]

Factors Influencing the Stability of Stems Fixed with Impaction Graft in Vitro

Hirotsugu Ohashi MD, PhD, Masanori Matsuura MD, Tsuneyuki Ebara MD, PhD, Yusaku Okamoto MD, PhD, Hironori Kou MD Mechanical stability of the stem is believed to be an important factor in successful impaction grafting in revision THA. We asked whether particle size, femoral bone deficiencies, stem design, graft composition, and impaction technique influenced the initial stability of the stem in vitro using model femora and human bone particles. Bone particles made with a reciprocating blade-type bone mill contained larger particles with a broader size distribution than those made by a rotating drum-type bone mill and had higher stiffness on compression testing. The stiffness on torsional testing decreased as the degree of proximal-medial segmental deficiencies increased. The stiffness and maximum torque in a stem with a rectangular cross section and wide anteroposterior surface were higher in torsional tests. Adding hydroxyapatite granules to the bone particles increased the torsional stability. To facilitate compact bone particles, we developed a spacer between the guidewire and modified femoral packers. This spacer facilitated compacting bone particles from the middle up to the proximal and the technique increased the amount of impacted bone particles at the middle of the stem and also improved the initial stability of the stem. Stem design and degree of deficiencies influenced stiffness in the torsional test and the addition of hydroxyapatite granules enhanced torsional stiffness.

Minimum 10-year Survival of Kerboull Cemented Stems According to Surface Finish

Moussa Hamadouche MD, PhD, François Baqué MD, Nicolas Lefevre MD, Marcel Kerboull MD The optimal surface finish for a cemented THA stem is still debated. We hypothesized surface finish would influence survival of Kerboull cemented hip arthroplasties and a matte finish would have lower survival. We reviewed survival of 433 total hip arthroplasties in 395 patients: 284 consecutive patients (310 hips) were enrolled in a prospective, randomized study of polished (165 hips) or matte finish stems (145 hips) and compared to a historical series of satin stems (123 hips) in 111 patients. The satin and matte finish implants had similar geometry but the polished was quadrangular rather than oval. Finish roughnesses were: polished (radius, 0.04 μm), satin (radius, 0.9 μm), and matte (radius, 1.7 μm). The mean age of the patients at the time of the index arthroplasty was 63.6 years. The survival rate at 13 years, using radiographic loosening as the end point, was 97.3% ± 2.6% for polished stems, 97.1% ± 2.1% for satin stems, and 78.9% ± 5.8% for matte stems. The data suggest survival of Kerboull stems was higher with a polished or satin surface finish than with a matte finish.,[object Object]

Measurement of Hip Range of Flexion-Extension and Straight-leg Raising

R. A. Elson FRCS, G. R. Aspinall FRCS We believe there is a degree of inaccuracy in the usual methods of evaluation of range at the hip in the sagittal plane, ie, flexion-extension. We describe a simple method of measuring more accurately the range of hip flexion-extension, presuming such ranges of motion should relate to the anatomic position of the pelvis. We used this technique for the measurement of flexion and extension of the left hip in a cohort of 200 healthy individuals; we found a wide range of both flexion (80°–140°) and extension (5°–40°). Especially with respect to extension, we believe more conventional methods underestimate the ranges of motion. As a corollary to this study, we suggest some reappraisal of the straight-leg–raising test by which pain from nerve root tension can be distinguished from a source of pain arising locally in intervertebral joints for mechanical reasons or from the hip itself. We recommend the method described as being useful in the consulting office.