Clinical Orthopaedics and Related Research ®

A Publication of The Association of Bone and Joint Surgeons ®

Published in
Clinical Orthopaedics and Related Research®
Volume 467 | Issue 9 | Sep, 2009
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]

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]

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]

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.

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]

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.

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.

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.

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]

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]

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]

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]

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.

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.

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]

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]

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]

Positive Culture Rate in Revision Shoulder Arthroplasty

James D. Kelly MD, E. Rhett Hobgood MD We recognized a trend of positive cultures taken from presumably uninfected shoulders during revision arthroplasty. Owing to the indolent nature of common shoulder pathogens such as Propionibacterium acnes, these cultures often become positive several days, even weeks, after surgery. Having concern regarding the potential importance of these positive cultures, we reviewed our revision arthroplasty population to determine the rate of positive intraoperative cultures in patients presumed to be aseptic, to characterize the isolated organisms, and to determine the subsequent development of infection. We retrospectively reviewed 27 patients (28 revisions) presumed to be uninfected between April 2005 and October 2007. Intraoperative cultures were positive in eight (29%) of the 28 revisions. Propionibacterium acnes was isolated in six. Methicillin-resistant Staphylococcus aureus was isolated in one patient and coagulase-negative Staphylococcus aureus was isolated in one patient. One-year followup was available on 24 of the 28 revisions. Two of the eight culture-positive revisions had a subsequent infection develop. Cultures taken at revision surgery for failed shoulder arthroplasty are often positive, and our findings document the importance of these positive cultures. Our data confirm previous reports isolating Propionibacterium acnes as a primary pathogen in revision shoulder arthroplasty.,[object Object]

Manufacturers Affect Clinical Results of THA with Zirconia Heads: A Systematic Review

Hiroyuki Yoshitomi MD, PhD, Satoru Shikata MD, PhD, Hiromu Ito MD, PhD, Takeo Nakayama MD, PhD, Takashi Nakamura MD, PhD In the 1980s, zirconia was introduced for THA with the expectation of lower polyethylene wear and better clinical results. However, several studies have reported poor survivorship of zirconia-polyethylene THA. We performed a systematic review and meta-analysis of zirconia-polyethylene THA to confirm or refute the theoretical advantages of this combination. Of 163 studies identified by a comprehensive search, seven met our selection criteria. These involved 769 hips of 586 patients with a mean age of 56.8 years and a minimum followup of 60 months (mean, 89.2 months; range, 60–155 months). The consolidated revision rate of zirconia-polyethylene THA at 89.2 months was higher than that of nonzirconia-polyethylene THA by 5% (risk difference, 0.05; 95% confidence interval, 0.02–0.08). Subgroup meta-analysis suggested THAs with zirconia heads from Ceraver had more revision surgery than nonzirconia heads (risk difference, 0.08; 95% confidence interval, 0.03–0.14), whereas zirconia heads from DePuy did not (risk difference, 0.02; 95% confidence interval, −0.01–0.06). The meta-analysis for annual linear polyethylene wear (which did not involve zirconia heads from Ceraver because of insufficient descriptions) showed no difference between zirconia and control groups. Collectively, THAs with high-quality zirconia heads appear to have prosthesis survivorship and polyethylene wear equivalent to those of THAs with traditional materials, but differing quality among zirconia heads could lead to poor survivorship of prostheses.,[object Object]

Long-term Periprosthetic Remodeling in THA Shows Structural Preservation

James B. Stiehl MD Although periprosthetic changes after THA have been well documented in short-term studies of less than 5 years, little is known about long-term changes. Long-term mineral changes must be evaluated against an unaffected limb control and for regional differences about a prosthesis. This study evaluated long-term periprosthetic remodeling using dual-energy xray absorptiometry in a prospective study of patients who had noncemented THAs with a modular titanium alloy proximal-loading prosthesis. In 15 randomly selected patients, bone mineral content was measured within 15 months of surgery and then at late mean followup of 13 years. In the affected femur, there was a major decrease in periprosthetic bone mineral content in Zones 1, 2, 6, and 7 (Gruen et al.) over the course of the study. The overall decrease in Zone 7 was 39% in bone mineral content. Estimates made after controlling for the contralateral unaffected femur indicate a major loss only in Zone 7 and preservation of mineral content in Zones 3, 4, and 5 of the proximal femur. The data suggest bone remodeling maintains the overall structural integrity of the upper femoral shaft.

CT Outperforms Radiography for Determination of Acetabular Cup Version after THA

Bernard Ghelman MD, Christopher K. Kepler MD, MBA, Stephen Lyman PhD, Alejandro González Della Valle MD Precise evaluation of acetabular cup version is necessary for patients with recurrent hip dislocation after THA. We retrospectively studied 42 patients, who underwent THAs, with multiple cross-table lateral radiographs and CT scans to determine whether radiographic or CT measurement of acetabular component version is more accurate. One observer measured cup version on all radiographs. CT scans were interpreted by one observer. Twenty radiographs were measured twice each by two observers to determine intraobserver and interobserver reliability. We implanted cups in four model pelvises using navigation and compared measurements of anteversion made with radiographs and CT scans. Intraclass correlation coefficients (ICC) for anteversion measurements of two observers were 0.9990 and 0.9998, respectively, when comparing measurements of identical radiographs (intraobserver). Paired values for two observers measuring the same radiograph had an ICC of 0.9686 (interobserver) compared with 0.7412 for measurements from serial radiographs of the same component. The ICC comparing radiographic versus CT-based measurements was 0.6981. CT measurements had stronger correlations with navigated values than radiographic measurements. Accuracy of anteversion measurements on cross-table radiographs depends on radiographic technique and patient positioning whereas properly performed CT measurements are independent of patient position.,[object Object]

Outcomes after THA in Patients with High Hip Dislocation after Childhood Sepsis

Young-Hoo Kim MD, Hee-Soo Seo MD, Jun-Shik Kim MD To ascertain whether THA in patients with high dislocation after childhood sepsis would relieve pain and improve function, we assessed the rate of postoperative infection, improvement in Harris hip and WOMAC scores, and improvement in range of motion after the THA in 62 patients (62 hips) with high dislocation (Crowe Type 4) after childhood sepsis. The revision rate and the incidence of complications also were assessed. The mean age of the patients was 47.5 years. The minimum followup was 13 years (mean, 15.2 years; range, 13–17 years). One patient had persistent infection. The mean preoperative Harris hip score of 55 points improved to 89 points at the final followup, and the mean preoperative WOMAC score of 65 points improved to 42 points. The mean combined preoperative arc of range of motion of 197° improved to 275°. Four cups (6%) and three stems (5%) were revised. Complications developed in nine hips (15%), but the rate of infection was low. Improved surgical technique and design of components provided favorable results for total hip replacement performed for complications of childhood sepsis in these young and active patients.,[object Object]

Does Regional Anesthesia Improve Outcome After Total Knee Arthroplasty?

Alan J. R. Macfarlane MBChB, Govindarajulu Arun Prasad MB BS, Vincent W. S. Chan MD, Richard Brull MD Total knee arthroplasty (TKA) is amenable to various regional anesthesia techniques that may improve patient outcome. We sought to answer whether regional anesthesia decreased mortality, cardiovascular morbidity, deep venous thrombosis and pulmonary embolism, blood loss, duration of surgery, pain, opioid-related adverse effects, cognitive defects, and length of stay. We also questioned whether regional anesthesia improved rehabilitation. To do so, we performed a systematic review of the contemporary literature comparing general anesthesia and/or systemic analgesia with regional anesthesia and/or regional analgesia for TKA. To reflect contemporary surgical and anesthetic practice, only randomized, controlled trials from 1990 onward were included. We identified 28 studies involving 1538 patients. There was insufficient evidence from randomized, controlled trials alone to conclude if anesthetic technique influenced mortality, cardiovascular morbidity other than postoperative hypotension, or the incidence of deep venous thrombosis and pulmonary embolism when using thromboprophylaxis. Our review suggests there was no difference in perioperative blood loss or duration of surgery in patients who received general anesthesia versus regional anesthesia. Compared with general anesthesia and/or systemic analgesia, regional anesthesia and/or analgesia reduced postoperative pain, morphine consumption, and opioid-related adverse effects. Length of stay may be reduced and rehabilitation facilitated for patients undergoing regional anesthesia and analgesia for TKA.,[object Object]

Differences between Sagittal Femoral Mechanical and Distal Reference Axes Should Be Considered in Navigated TKA

Byung June Chung MD, Yeon Gwi Kang BS, Chong Bum Chang MD, PhD, Sung Ju Kim MS, Tae Kyun Kim MD, PhD In computer-assisted TKA, surgeons determine positioning of the femoral component in the sagittal plane based on the sagittal mechanical axis identified by the navigation system. We hypothesized mechanical and distal femoral axes may differ on lateral views and these variations are influenced by anteroposterior bowing and length of the femur. We measured angles between the mechanical axis and distal femoral axis on 200 true lateral radiographs of the whole femur from 100 adults. We used multivariate linear regression to identify predictors of differences between the axes. Depending on the method used to define the two axes, the mean angular difference between the axes was as much as 3.8° and as little as 0.0°, with standard differences ranging from 1.7° to 1.9°. Variation between the two axes increased with increased femoral bowing and increased femoral length. Surgeons should consider differences between the mechanical axes and distal femoral axes when they set the sagittal plane position of a femoral component in navigated cases. Our findings also may be relevant when measuring rotation of the femoral component in the sagittal plane from postoperative radiographs or when interpreting femoral component sagittal rotation results reported in other studies.,[object Object]

Correlations between Knee Society Function Scores and Functional Force Measures

Cale A. Jacobs PhD, Christian P. Christensen MD Subjective evaluations often are used after knee arthroplasty to quantify function; however, these scores may be influenced by pain and/or function of the nonoperated limb. Multiple influences increase variability of these scores, which in turn may result in a greater change in score required to be considered clinically important. We determined the relationships among the Knee Society pain and function scores, range of motion (ROM), and functional force measures of the surgically treated and nonoperated limbs. Before and 3 months after total or unicompartmental knee arthroplasty, 36 patients answered questions necessary to calculate the Knee Society pain and function scores. A dual-force platform was used to record the lift-up force of each limb during a stepping task. Function scores were correlated to pain scores, lift-up force of the nonoperated limb, and ROM before surgery. After surgery, function scores correlated with pain scores but not with objective functional measures or ROM. As patient-reported function scores and functional force measures of the surgically treated limb seem to provide distinctly different information, both measures may need to be collected after knee arthroplasty to fully understand a patient’s functional recovery.

Massive Bone Loss from Fungal Infection after Anterior Cruciate Ligament Arthroscopic Reconstruction

D. Luis Muscolo MD, Lisandro Carbo MD, Luis A. Aponte-Tinao MD, Miguel A. Ayerza MD, Arturo Makino MD Although there are numerous reports of septic pyogenic arthritis after arthroscopic anterior cruciate ligament (ACL) reconstruction, there is limited information regarding the outcomes of fungal infection. We determined the outcomes of six patients with mycotic infection after regular ACL reconstruction. There were four males and two females with a mean age of 33 years. We determined the number of procedures performed, bone loss originating to control infection, and final reconstruction in these patients. An average of five arthroscopic lavage procedures had been performed at the referring centers. Fungal infection was diagnosed based on pathologic samples; five infections were the result of mucormycosis and one was Candida. After final débridement, the mean segmental bone loss was 12.8 cm. All patients were treated with intravenous antifungal coverage and cement spacers before final reconstruction. At final followup, all patients were free of clinical infection. Three had reconstruction with an allograft-prosthesis composite, two with hemicylindrical allografts, and one with an intercalary allograft arthrodesis. Despite the extremely unusual presentation of this complication, surgeons should be aware of potential and catastrophic consequences of this severe complication after ACL reconstruction.,[object Object]

Cemented versus Uncemented Hemiarthroplasty for Displaced Femoral Neck Fractures

Wender Figved MD, Vidar Opland MD, Frede Frihagen MD, Tore Jervidalo MD, Jan Erik Madsen MD, PhD, Lars Nordsletten MD, PhD Hemiarthroplasty is the most commonly used treatment for displaced femoral neck fractures in the elderly. There is limited evidence in the literature of improved functional outcome with cemented implants, although serious cement-related complications have been reported. We performed a randomized, controlled trial in patients 70 years and older comparing a cemented implant (112 hips) with an uncemented, hydroxyapatite-coated implant (108 hips), both with a bipolar head. The mean Harris hip score showed equivalence between the groups, with 70.9 in the cemented group and 72.1 in the uncemented group after 3 months (mean difference, 1.2) and 78.9 and 79.8 after 12 months (mean difference, 0.9). In the uncemented group, the mean duration of surgery was 12.4 minutes shorter and the mean intraoperative blood loss was 89 mL less. The Barthel Index and EQ-5D scores did not show any differences between the groups. The rates of complications and mortality were similar between groups. Both arthroplasties may be used with good results after displaced femoral neck fractures.,[object Object]

Predictors of Success on the American Board of Orthopaedic Surgery Examination

James H. Herndon MD, Bassan J. Allan MD, George Dyer MD, Andrew Jawa MD, David Zurakowski PhD Predictors of success of orthopaedic residents on the American Board of Orthopaedic Surgery (ABOS) examination are controversial. We therefore evaluated numerous variables that may suggest or predict candidate performance on the ABOS examination. We reviewed files of 161 residents (all graduates) from one residency program distributed into two study groups based on whether they passed or failed their first attempt on the ABOS Part I or Part II examination from 1991 through 2005. Predictors of success/failure on the ABOS I included the mean percentile score on the Orthopaedic In-Training Examination (OITE) (Years 2 through 4), the percentile OITE score in the last year of training, US Medical Licensing Examination (USMLE) score, Dean’s letter, election to Alpha Omega Alpha (AOA), and number of honors in selected third-year clerkships. All but the USMLE score predicted passing the ABOS Part II examination. These data suggest there are objective predictors of residents’ performance on the ABOS Part I and Part II examinations.

Anatomy of the Intracortical Canal System: Scanning Electron Microscopy Study in Rabbit Femur

Ugo E. Pazzaglia MD, Terenzio Congiu MD, Mario Raspanti MD, Federico Ranchetti MD, Daniela Quacci MD The current model of compact bone is that of a system of longitudinal (Haversian) canals connected by transverse (Volkmann’s) canals. Models based on histology or microcomputed tomography lack the morphologic detail and sense of temporal development provided by direct observation. Using direct scanning electron microscopy observation, we studied the bone surface and structure of the intracortical canal system in paired fractured surfaces in rabbit femurs, examining density of canal openings on periosteal and endosteal surfaces, internal network nodes and canal sizes, and collagen lining of the inner canal system. The blood supply of the diaphyseal compact bone entered the cortex through the canal openings on the endosteal and periosteal surfaces, with different morphologic features in the midshaft and distal shaft; their density was higher on endosteal than on periosteal surfaces in the midshaft but with no major differences among subregions. The circumference measurements along Haversian canals documented a steady reduction behind the head of the cutting cone but rather random variations as the distance from the head increased. These observations suggested discontinuous development and variable lamellar apposition rate of osteons in different segments of their trajectory. The frequent branching and types of network nodes suggested substantial osteonal plasticity and supported the model of a network organization. The collagen fibers of the canal wall were organized in intertwined, longitudinally oriented bundles with 0.1- to 0.5-μm holes connecting the canal lumen with the osteocyte canalicular system.

Case Report: Kaposiform Hemangioendothelioma in Multiple Spinal Levels Without Skin Changes

Jennifer W. Lisle MD, Heather A. Bradeen MD, Alexandra N. Kalof MD Kaposiform hemangioendothelioma is a rare vascular tumor of childhood that is locally aggressive but has little metastatic potential and by itself is not known to be lethal. It most commonly presents as a superficial or deep soft tissue mass with associated cutaneous lesions. Kasabach-Merritt phenomenon, a condition characterized by profound thrombocytopenia and life-threatening hemorrhage, often is associated with kaposiform hemangioendothelioma. Six cases of kaposiform hemangioendothelioma have been reported in bone, two of which were located in extracraniofacial bones. We report a diagnostically challenging case of a 6-year-old girl with kaposiform hemangioendothelioma of the thoracolumbar spine without Kasabach-Merritt phenomenon or cutaneous lesions.

Case Report: Dysplasia Epiphysealis Hemimelica: A Case Report with Novel Pathophysiologic Aspects

Mario Perl MD, Rolf E. Brenner MD, Sabine Lippacher MD, Manfred Nelitz MD Dysplasia epiphysealis hemimelica (DEH) is a rare developmental disorder. The underlying pathophysiology is largely unclear. Its diagnosis is based on clinical findings and may be difficult due to its low incidence and close relationship to other disorders such as osteochondroma. We describe a 13-year-old boy who presented with a unilateral lesion of the left medial femoral condyle and left ankle. In addition to standard diagnostic tools such as radiographs and MRI, arthroscopy-guided biopsy was performed; histologic/immunohistochemical findings from cartilage-bone specimens confirmed the diagnosis and provided novel information toward a disease mechanism. The cellular phenotype of clustered chondrocytes exhibited characteristics of chondroprogenitor cells and terminally differentiated cells, suggesting dysregulation of resident progenitor cells. No other surgery was performed and during a 2 year period, we observed spontaneous ossification of the lesion associated with decreased joint impairment. Immunohistochemical analysis of the lesion provided a more accurate diagnosis and may contribute to unraveling potential novel mechanisms involved in its pathogenesis.

Idiopathic Equinocavovarus Foot Deformity in an 8-year-old Girl

Keith J. Joe MD, MC, USAF, Sonny S. Huitron DO, MC, USA, John J. Crawford MD, MC, USA, Spencer J. Frink MD, MC, USAF
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