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 4 | Apr, 2009

The Anatomy of the Acetabulum: What is Normal?

Viktor Krebs MD, Stephen J. Incavo MD, William H. Shields BS Published studies of the human hip make frequent reference to the normal pelvis and acetabulum. However, other than qualitative descriptions we found no clinically applicable published references describing a normal pelvis and acetabulum; such information is important for designing certain kinds of implants (eg, reconstruction cages). We describe a method to quantify, average, and apply data gathered from normal human specimens to create a standard representation of the ilium and ischium. One hundred healthy hemipelves from 50 human skeletons were evaluated. We measured angles and distances between major anatomic landmarks in the pelvis. The data collected were analyzed for variance and averaged to create a normal topographic map. Finally, we examined several commercially available acetabular reconstruction cages to determine the fit to the anatomically determined normal pelvis. These results provide a representation of true acetabular geometry and may serve as the basis for future acetabular reconstruction cage design.

Proximal Femoral Anatomy in the Normal Human Population

Paul A. Toogood BS, Anthony Skalak MD, Daniel R. Cooperman MD In this study, we developed a complete description of the morphology of the proximal femur. Then, using this framework, we (1) determined normal population means, standard deviations, and ranges; (2) established differences among subpopulations; and (3) showed correlations among the various measurements. To accomplish these objectives, we analyzed 375 adult femurs. Specimens were digitally photographed in standardized positions, measurements being obtained using ImageJ software. Three parameters of the head-neck relationship were assessed. Translation was examined through four raw offset measurements (anterior, posterior, superior, inferior) used to calculate anterior-posterior and superior-inferior ratios. Rotation was investigated through anteroposterior (AP) and lateral physeal angles. Concavity was examined using alpha, beta, gamma, and delta angles. Two parameters of the neck-shaft relationship were assessed, neck version and angle of inclination. Average anterior-posterior and superior-inferior ratios were 1.14 and 0.90. Average AP and lateral physeal angles were 74.33° and 81.83°, respectively. Averages for alpha, beta, gamma, and delta angles were 45.61°, 41.85°, 53.46°, and 42.95°, respectively. Average neck version and angle of inclination were 9.73° and 129.23°, respectively. Differences existed between males and females and between those younger and older than 50 years. Correlations were observed between translation and concavity, and translation and the neck-shaft relationships.,[object Object]

Can the Acetabular Position be Derived from a Pelvic Frame of Reference?

Wael Dandachli MRCS, Amgad Nakhla MRCS, Farhad Iranpour MD, Vijayaraj Kannan MS(Orth), Justin P. Cobb FRCS [object Object]

Joint Congruency as an Indication for Rotational Acetabular Osteotomy

Kunihiko Okano MD, PhD, Hiroshi Enomoto MD, PhD, Makoto Osaki MD, PhD, Hiroyuki Shindo MD, PhD Long-term results of periacetabular osteotomy for advanced-stage osteoarthritis secondary to developmental dysplasia of the hip are reportedly unsatisfactory compared with results for early-stage osteoarthritis. Other preoperative information that can be used to determine indications for periacetabular osteotomy is therefore important to avoid performing osteotomy in young patients with advanced-stage osteoarthritis who would not likely achieve substantial benefit. We retrospectively reviewed 47 patients (49 hips) with advanced-stage osteoarthritis who underwent rotational acetabular osteotomy (RAO) using preoperative congruency in abduction. The minimum postoperative followup was 8 years (mean, 12.3 years; range, 8–20 years) and mean age at surgery was 43.1 years (range, 30–59 years). At followup, osteoarthritic stage was improved in 12 hips, unchanged in 24 hips, and had progressed in 13 hips. Preoperative joint congruency in abduction was good in 13 hips, poor in 32 hips, and narrowed in four hips. Patients with better congruency in abduction had better results. We believe osteoarthritis with good congruency in abduction preoperatively remains a good indication for RAO even in advanced stages of disease.,[object Object]

Toward a Dynamic Approach of THA Planning Based on Ultrasound

Guillaume Dardenne MS, Stéphane Dusseau MD, Chafiaâ Hamitouche PhD, Christian Lefèvre MD, Eric Stindel MD, PhD The risk of dislocation after THA reportedly is minimized if the acetabular implant is oriented at 45° inclination and 15° anteversion with respect to the anterior pelvic plane. This reference plane now is used in computer-assisted protocols. However, this static approach may lead to postoperative instability because the dynamic variations of the pelvis influence effective cup orientation and are not taken into account in this approach. We propose an ultrasound tool to register the preoperative dynamics of the pelvis for THA planning during computer-assisted surgery. To assess this pelvic behavior and its consequences on implant orientation, we tested a new 2.5-dimensional ultrasound-based approach. The pelvic flexion was registered in sitting, standing, and supine positions in 20 subjects. The mean values were −25.2° ± 5.8° (standard deviation), 2.4° ± 5.1°, and 6.8° ± 3.5°, respectively. The mean functional anteversion varied by 26° and the mean functional inclination by 12° depending on the pelvic flexion. We therefore recommend including dynamic pelvic behavior to minimize dislocation risk. The notion of a safe zone should be revisited and extended to include changes with activity.

A New Digital Preoperative Planning Method for Total Hip Arthroplasties

Hendrikus J. A. Crooijmans MSc, Armand M. R. P. Laumen MD, Carola Pul PhD, Jan B. A. Mourik MD Preoperative templating is an important part of a THA. The ability to accurately determine magnification of the hip on the radiograph and apply identical magnification to the radiograph and template will improve accuracy of preoperative templating of THA. We designed a templating method using a new way of determining the hip magnification with a linear relationship between magnification of the hip and the reference object on top of the pubis symphysis; the relationship was determined on 50 radiographs. We then compared our method with two other templating methods: an analog method assuming an average hip magnification of 15% and a digital method determining the hip magnification with a one-to-one relationship between the reference object and the hip. All methods were reproducible. Uniform undersizing occurred when templating with the digital method based on the one-to-one relationship; the analog method best predicted the implanted prosthesis size, closely followed by our new digital templating method; the new method will be particularly applicable for preoperative THA when analog methods are replaced by digital methods.

Component Alignment in Hip Resurfacing Using Computer Navigation

Chris Bailey FRCS(Tr&Orth), Rehan Gul FRCS(Tr&Orth), Mark Falworth FRCS(Tr&Orth), Steven Zadow FRANZCR, Roger Oakeshott FRACS The use of computer navigation during hip resurfacing has been proposed to reduce the risk of a malaligned component and notching with subsequent postoperative femoral neck fracture. Femoral component malalignment and notching have been identified as the major factors associated with femoral neck fracture after hip resurfacing. We performed 37 hip resurfacing procedures using an imageless computer navigation system. Preoperatively, we generated a patient-specific computer model of the proximal femur and planned a target angle for placement of the femoral component in the coronal plane. The mean navigation angle after implantation (135.5°) correlated with the target stem-shaft angle (135.4°). After implantation, the mean stem-shaft angle of the femoral component measured by three-dimensional computed tomography (135.1°) correlated with the navigation target stem-shaft angle (135.4°). The computer navigation system generates a reliable model of the proximal femur. It allows accurate placement of the femoral component and provides precise measurement of implant alignment during hip resurfacing, thereby reducing the risk of component malpositioning and femoral neck notching.

Does Hip Resurfacing Require Larger Acetabular Cups Than Conventional THA?

Florian D. Naal MD, Michael S. H. Kain MD, Otmar Hersche MD, Urs Munzinger MD, Michael Leunig MD [object Object],[object Object]

Use of a Trochanteric Flip Osteotomy Improves Outcomes in Pipkin IV Fractures

Brian D. Solberg MD, Charles N. Moon MD, Dennis P. Franco MD The optimal surgical approach for combined femoral head and acetabular fractures (Pipkin IV) is controversial because of their rarity and lack of definitive reports. Surgical dislocation with trochanteric flip osteotomy (TFO) allows simultaneous exposure of the acetabulum and femoral head. We protected the obturator internus and inferior capsule during repair with a heavy suture at the inferior extent of the traumatic capsulotomy. We retrospectively reviewed 12 patients with Pipkin IV fractures treated using this approach during a 6-year period. The minimum followup was 24 months (mean, 47 months; range, 24–71 months). Clinical outcomes were measured using the Merle d’Aubigné-Postel and Thompson-Epstein scoring scales. Radiographically, all patients achieved healing of their acetabular fractures; 11 achieved healing of the femoral head fracture and osteonecrosis developed in one patient. The average Merle d’Aubigné-Postel score was 15.6 of 18; using the Thompson-Epstein score, 10 of the 12 patients had good or excellent outcomes, one had a fair outcome, and one had a poor outcome. Trochanteric flip osteotomy allowed for simultaneous exposure and repair of both lesions in Pipkin IV fractures. Using a uniform surgical protocol with TFO rendered clinical results comparable to previously reported outcomes in series of isolated femoral head fractures.,[object Object]

Femoral Oxygenation During Hip Resurfacing Through the Trochanteric Flip Approach

Robert T. Steffen MRCS, Darren Fern FRCS, Mark Norton FRCS, David W. Murray FRCS, Harinderjit S. Gill DPhil Femoral neck fracture is one of the most common complications of hip resurfacing and considered by some to be related to reduced blood flow as a consequence of the surgical approach. We measured oxygen concentration during hip resurfacing through the trochanteric flip approach (n = 15 patients) and compared this approach with previous data for the posterior and anterolateral approaches. With the trochanteric flip the average femoral oxygenation decreased during the procedure to approximately 50% of that at the start, however it recovered to starting level by the end of the procedure. Preservation of oxygenation with the trochanteric flip was similar to that observed with the anterolateral approach, but with less variation during the procedure. Both of these approaches were superior in terms of oxygenation preservation to the posterior approach which resulted in a dramatic reduction in oxygenation.

MRI Shows Biologic Restoration of Posterior Soft Tissue Repairs after THA

Paul M. Pellicci MD, Hollis G. Potter MD, Li F. Foo MD, Friedrich Boettner MD Although posterior capsule repair reduces the incidence of dislocation after THA, radiographic imaging studies suggest a high failure rate of the repair. Using MRI, we prospectively followed patients to evaluate the integrity of the posterior soft tissue repair after primary THA. Thirty-six patients (21 men, 15 women) underwent arthroplasty using a standard posterior approach. The posterior capsule and external rotators were repaired as separate layers using nonabsorbable sutures through two drill holes in the greater trochanter. Patients observed postoperative hip precautions for 6 weeks after surgery. All patients underwent initial MRI between postoperative Days 2 and 4. Thirty patients returned for followup MRI 3 months after surgery. At 3 months followup, the posterior capsule remained intact in 27 of 30 patients (90%) and the quadratus femoris repair remained intact in 29 of 30 patients (97%). Thirteen of 30 piriformis tendon repairs (43%) and 17 conjoined tendon repairs (57%) showed a gap between the hypointense tendon end and the greater trochanter greater than 25 mm. Our data show repaired posterior soft tissues provide a biologic scaffold allowing formation of a posterior pseudocapsule.

Circulating Cytokines after Hip and Knee Arthroplasty: A Preliminary Study

Kalpesh Shah MRCS, Aslam Mohammed FRCS, T&Orth, Sanjeev Patil FRCS, T&Orth, Angus McFadyen PhD, R. M. D. Meek FRCS, T&Orth Several studies show cytokine concentrations in the peripheral blood are associated with inflammatory activity and surgical trauma. Cytokine concentrations have more rapid increase and quicker return to normal values than either C-reactive protein or erythrocyte sedimentation rate – a matter of hours rather than weeks; some studies suggest they are better predictors of postoperative infection than C-reactive protein and erythrocyte sedimentation rate. Threshold levels of interleukin-6 after joint arthroplasty have been determined, but levels of other potentially useful cytokines (tumor necrosis factor-α, interleukin-8, interleukin-10, etc) are not known. We measured the serum levels of 25 different cytokines before and after hip and knee arthroplasties and identified those associated with surgical trauma. Peripheral venous blood samples (one preoperative and three postoperative) from 49 patients undergoing hip or knee arthroplasty were analyzed by laser chromatography. Three of the 25 cytokines had a relationship with postsurgical trauma, which included one deep infection. Serum levels of these three cytokines might be useful to identify periprosthetic infections during the early postoperative period when C-reactive protein and erythrocyte sedimentation rate remain elevated.,[object Object]

Reliability and Validity of the Cross-Culturally Adapted German Oxford Hip Score

Florian D. Naal MD, Marc Sieverding MD, Franco M. Impellizzeri MS, Fabian Knoch MD, Anne F. Mannion PhD, Michael Leunig MD There is currently no German version of the Oxford hip score. Therefore we sought to cross-culturally adapt and validate the Oxford hip score for use with German-speaking patients (OHS-D) with osteoarthritis of the hip using a forward-backward translation procedure. We then assessed the new score in 105 consecutive patients (mean age, 63.4 years; 48 women) undergoing THA. We specifically determined: the number of fully completed questionnaires, reliability, concurrent validity by correlation with the WOMAC, Harris hip score, and SF-12, and distribution of floor and ceiling effects. We received 96.6% fully completed questionnaires. An intraclass correlation coefficient of 0.90 and Cronbach’s alpha of 0.87 suggested the OHS-D was reliable. Correlation coefficients between the OHS-D and the WOMAC total score, pain subscale, stiffness subscale, and physical function subscale were 0.82, 0.70, 0.68, and 0.82, respectively. OHS-D correlated with the Harris hip score (r = 0.63) and the physical component scale of the SF-12 (r = 0.58). We observed no ceiling or floor effects. The OHS-D appeared a reliable and valid measurement tool for assessing pain and disability with German-speaking patients with hip osteoarthritis.,[object Object]

Which is the Best Activity Rating Scale for Patients Undergoing Total Joint Arthroplasty?

Florian D. Naal MD, Franco M. Impellizzeri MS, Michael Leunig MD We compared the metric properties of the University of California, Los Angeles (UCLA) activity scale, the Tegner score, and the Activity Rating Scale for assessment of activity levels in 105 patients undergoing THA (48 women; mean age, 63.4 years) and 100 patients undergoing TKA (61 women; mean age, 66.5 years). We assessed construct validity by correlating these scales with the International Physical Activity Questionnaire and different traditional patient self-reporting outcome measures. Test-retest reliability, feasibility, and floor and ceiling effects also were determined. The UCLA scale showed the strongest correlations with the other measures (r = −0.35 to 0.56 for THA; r = −0.55 to 0.23 for TKA) and was the only scale that discriminated between insufficiently and sufficiently active patients undergoing THA and TKA. The UCLA scale had the best reliability, provided the highest completion rate, and showed no floor effects. It seems to be the most appropriate scale for assessment of physical activity levels in patients undergoing total joint arthroplasty.,[object Object]

Open versus Two Forms of Arthroscopic Rotator Cuff Repair

Neal L. Millar MBChB, MRCS, Xiao Wu MBBS, Robyn Tantau AMS, Elizabeth Silverstone MBBS, George A. C. Murrell MBBS, DPhil, MD [object Object],[object Object]

Cross-linked Compared with Historical Polyethylene in THA: An 8-year Clinical Study

Carel H. Geerdink MD, Bernd Grimm PhD, Wendy Vencken, Ide C. Heyligers MD, PhD, Alphons J. Tonino MD, PhD Wear particle-induced osteolysis is a major cause of aseptic loosening in THA. Increasing wear resistance of polyethylene (PE) occurs by increasing the cross-link density and early reports document low wear rates with such implants. To confirm longer-term reductions in wear we compared cross-linked polyethylene (irradiation in nitrogen, annealing) with historical polyethylene (irradiation in air) in a prospective, randomized clinical study involving 48 patients who underwent THAs with a minimum followup of 7 years (mean, 8 years; range, 7–9 years). The insert material was the only variable. The Harris hip score, radiographic signs of osteolysis, and polyethylene wear were recorded annually. Twenty-three historical and 17 moderately cross-linked polyethylene inserts were analyzed (five patients died, three were lost to followup). At 8 years, the wear rate was lower for cross-linked polyethylene (0.088 ± 0.03 mm/year) than for the historical polyethylene (0.142 ± 0.07 mm/year). This reduction (38%) did not diminish with time (33% at 5 years). Acetabular cyst formation was less frequent (39% versus 12%), affected fewer DeLee and Charnley zones (17% versus 4%), and was less severe for the cross-linked polyethylene. The only revision was for an aseptically loose cup in the historical polyethylene group. Moderately cross-linked polyethylene maintained its wear advantage with time and produced less osteolysis, showing no signs of aging at mid-term followup.,[object Object]

Delamination Cysts: A Predictor of Acetabular Cartilage Delamination in Hips with a Labral Tear

Marie Gdalevitch MD, Karen Smith CRA, Michael Tanzer MD The treatment and prognosis of labral tears of the hip depend primarily on whether there is concomitant injury of the adjacent acetabular articular cartilage. We asked whether a delamination cyst on the preoperative plain radiographs correlated with delamination of the acetabular articular cartilage at the time of hip arthroscopy. We reviewed the preoperative radiographs of 125 consecutive hips that had a labral tear at hip arthroscopy for the presence of a delamination cyst. A delamination cyst was defined as an acetabular subchondral cyst either directly adjacent to a lateral acetabular cyst or in relation to a subchondral crack in the anterosuperior portion of the acetabulum. All patients with acetabular cartilage delamination at arthroscopy were identified. There were 16 patients with delamination cysts on radiographs and 15 patients with cartilage delamination at arthroscopy. A delamination cyst on the preoperative anteroposterior and/or frog lateral radiographs of the hip accurately predicted acetabular cartilage delamination, especially in hips with labral tears not caused by a major trauma. A delamination cyst is a previously unrecognized and novel radiographic sign that can preoperatively identify acetabular cartilage delamination in patients with labral tears, thereby facilitating the selection of the appropriate surgery and determining prognosis.,[object Object]

Hip Resurfacing Arthroplasty: Risk Factors for Failure Over 25 Years

Eric J. Yue MD, Miguel E. Cabanela MD, Gavan P. Duffy MD, Michael G. Heckman MS, Mary I. O’Connor MD Many early metal-on-polyethylene hip resurfacing arthroplasty designs were abandoned after reports of high short-term and midterm failure rates. To investigate factors associated with failure, we retrospectively reviewed our experience with early-design hip resurfacing implants in 75 patients during a 25-year period (median followup, 7.9 years; range, 0.1–25.2 years). Implant failure was defined as revision for any reason. One of 75 patients was lost to followup. The estimated rate of implant survival was 73% at 5 years, 34% at 10 years, 27% at 15 years, 12% at 20 years, and 8% at 25 years. Of the many clinical and radiographic factors considered, only age, implant type, and gender were associated with implant survival independent of other variables considered. Hip resurfacing arthroplasty showed poor overall long-term survival in this series. Particular attention should be paid to the identified risk factors as long-term followup data become available for modern designs.,[object Object]

TKA Sagittal Alignment with Navigation Systems and Conventional Techniques Vary Only a Few Degrees

Yukihide Minoda MD, PhD, Akio Kobayashi MD, PhD, Hiroyoshi Iwaki MD, PhD, Hirotsugu Ohashi MD, PhD, Kunio Takaoka MD, PhD Navigation systems have been developed to achieve more reliable prosthetic alignment in TKAs. However, the component alignment in the sagittal plane is reportedly less reliable than in the coronal plane even with navigation systems. We measured and compared sagittal prosthetic alignments for TKAs with the conventional technique and three navigation approaches to establish reference frames, using radiographs of the entire lower extremity while standing. The sagittal alignments simulated on the radiographs with the conventional technique and navigation systems differed by a mean of 2° to 4°. Use of navigation systems resulted in a mean of 1° to 4° hyperextension between the femoral and tibial components and use of the conventional technique resulted in a mean of 1° flexion. Use of different reference points on the distal femoral condyle for the navigation systems resulted in differences of as much as 3° alignment in the sagittal plane. Although optimal prosthetic alignment for TKA in the sagittal plane is unknown, surgeons and technicians using navigation systems should be aware of this difference in the sagittal plane and the risk of hyperextension between the femoral and tibial components, which might be associated with osteolysis and anterior post-cam impingement.

Clinical Implications of Anthropometric Patellar Dimensions for TKA in Asians

Tae Kyun Kim MD, PhD, Byung June Chung MD, Yeon Gwi Kang BS, Chong Bum Chang MD, PhD, Sang Cheol Seong MD, PhD Anthropometric patellar dimensions can influence implant design and surgical techniques in patellar resurfacing for TKA. We measured anthropometric patellar dimensions in 752 osteoarthritic knees (713 in females and 39 in males) treated with TKA in 466 Korean patients and compared them with reported dimensions for Western patients. We investigated the effects of postoperative overall thickness deviations, residual bony thickness after bone resection, and postoperative deviations of component center positions from median ridge positions versus clinical and radiographic outcomes evaluated 1 year after surgery. Korean patients undergoing TKA had thinner and smaller patellae than Western patients. We found no associations between preoperative to postoperative overall thickness differences and clinical and radiographic outcomes and no differences between knees with a residual bony thickness 12 mm or greater and knees with a residual thickness less than 12 mm, with the exception of WOMAC pain scores. We found no associations between postoperative deviations of component center position and clinical or radiographic outcomes. Our findings indicate bone resection for patellar resurfacing can be flexible without jeopardizing clinical outcome.,[object Object]

Effects of the Balanced Gap Technique on Femoral Component Rotation in TKA

Petra J. C. Heesterbeek MSc, Wilco C. H. Jacobs MSc, Ate B. Wymenga MD, PhD Femoral component rotation from a total knee prosthesis can be determined by either a measured resection technique or a balanced gap technique. With the balanced gap implantation technique, femoral component rotation can vary freely within the restrictions produced by soft tissue structures. Because internal rotation might cause patella problems, the effect of ligament releases on femoral component rotation in a prospective clinical study was studied. Femoral component rotation was measured intraoperatively with a tensor applied in flexion at 150 N in 87 knees. Great interpatient variability was found; femoral component rotation, reference from the posterior condyles, ranged from −4° to 13°. There was no difference in femoral component rotation of knees with or without ligament releases in extension. However, knees with major medial release had less external femoral component rotation than knees with minor lateral releases. Preoperative alignment had no influence on femoral component rotation. The use of the balanced gap implantation technique theoretically will result in a balanced flexion gap, but the amount of femoral component rotation will be variable owing to patient variability and variation in ligament releases.,[object Object]

Estimation of Patient Dose and Associated Radiogenic Risks from Limb Lengthening

Frank M. Schiedel MD, Tim C. Buller MD, Robert Rödl MD Limb-lengthening procedures include a series of radiographic examinations to follow the lengthening process and callus formation. We quantified ionizing radiation exposure during lengthening treatment and estimated the risks associated with this exposure in 53 patients undergoing lengthening procedures. Field size and tube voltage of all radiographs and fluoroscopy time during surgery were recorded. According to conversion factor tables of organ doses, the cumulative organ dose was estimated. Location of lengthening, age, complications during lengthening procedure, range of lengthening, healing index, and other factors affecting the duration of the lengthening procedures were analyzed. Average lengthening was 4.8 cm (range, 3.0–12.5 cm). The average cumulative organ dose for a straight lengthening procedure was 3.1 mSv (range, 0.2–12.5 mSv). The average organ dose per centimeter of lengthening was 0.7 mSv/cm (range, 0.03–5.9 mSv/cm). Doses for patients with tibial lengthening (0.3 mSv/cm) were less than doses for patients with femoral lengthening (1.1 mSv/cm). Age, complications, range of lengthening, and healing index did not influence the dosage of radiation per centimeter lengthening. We judge the average patient’s exposure during a limb-lengthening procedure as tolerable, but femur lengthening results in a higher cumulative organ dose.,[object Object]

Treatment of Canine Osseous Tumors with Photodynamic Therapy: A Pilot Study

S. Burch MSc, MD, C. London PhD, DVM, B. Seguin DVM, C. Rodriguez PhD, DVM, B. C. Wilson PhD, S. K. Bisland PhD [object Object]

Proximal Humerus Reconstructions for Tumors

Benjamin K. Potter MD, Sheila C. Adams MD, J. David Pitcher MD, Theodore I. Malinin MD, H. Thomas Temple MD The optimal method for reconstructing the proximal humerus in patients with tumors is controversial. To determine functional outcomes and complication rates after different types of reconstructions, we reviewed a consecutive series of 49 patients who underwent proximal humerus resection and osteoarticular allograft (17 patients), allograft-prosthetic composite (16), or endoprosthetic (16) reconstruction. Operative indications included primary malignancies (24 patients), metastatic disease (19), and benign aggressive disease (six). Implant revision was more common after osteoarticular reconstruction (five of 17) than after allograft-prosthetic composite (one of 16) or endoprosthetic (zero of 16) reconstructions. At a minimum followup of 24 months (median, 98 months; range, 24–214 months) in surviving patients, Musculoskeletal Tumor Society functional scores averaged 79% for the allograft-prosthetic composite, 71% for the osteoarticular allograft, and 69% for the endoprosthetic reconstruction cohorts. Shoulder instability was associated with abductor mechanism compromise and was more common after endoprosthetic reconstruction. Allograft fractures occurred in 53% of patients receiving osteoarticular allografts. We recommend allograft-prosthetic composite reconstruction for younger patients with primary tumors of bone and endoprosthetic reconstruction for older patients with metastatic disease. Because of the unacceptable complication rate, we do not recommend osteoarticular allograft reconstruction for routine use in the proximal humerus.,[object Object]

Comparable Results Between Lateralized Single- and Double-bundle ACL Reconstructions

Eiichi Tsuda MD, Yasuyuki Ishibashi MD, Akira Fukuda MD, Harehiko Tsukada MD, Satoshi Toh MD Patellar tendon autografts are not suitable for multibundle ACL reconstruction, a procedure that reportedly enhances postoperative knee stability. Biomechanical studies recommend lateral placement of the femoral tunnel for single-bundle reconstruction to improve postoperative knee kinematics. We asked whether a lateralized single-bundle patellar tendon graft (LSBP) would provide good short-term results of ACL reconstruction comparable to double-bundle hamstring tendon grafts (DBH). We prospectively followed 144 patients with unilateral ACL rupture treated with either LSBP or DBH in a nonrandomized fashion. Twenty-four female and 31 male patients with LSBP and 44 female and 26 male patients with DBH were followed for a minimum of 24 months (average, 38 months; range, 24–56 months). The patients with LSBP recovered knee extension better at 1 month compared with the patients with DBH, but extension was similar after 3 months. We observed no differences in the side-to-side difference of KT1000™ measurement, pivot shift test, or anterior drawer test between LSBP and DBH. Although better recovery of hamstring strength in LSBP and better recovery of quadriceps strength in DBH were observed in the early postoperative period, these differences disappeared after 12 months. There was no difference in International Knee Documentation Committee objective evaluation between LSBP and DBH at the final followup.,[object Object]

Tricortical Bone Grafts for Treatment of Malaligned Tibias and Fibulas

Joseph Borrelli MD, Stéphane Leduc MD, FRCSC, Ronald Gregush MD, William M. Ricci MD Malunions and malaligned nonunions of the tibia and fibula after fracture alter limb function and can be corrected only with surgical intervention. We sought to determine whether using tricortical portions of the iliac crest in conjunction with osteotomy and internal fixation could successfully treat malunions and malaligned nonunions of the tibia and fibula. Seventeen patients with either a malunion or a malaligned nonunion of the tibia or fibula were treated with an osteotomy, deformity correction, and placement of an autogenous iliac crest tricortical bone graft with open reduction and internal fixation (ORIF). The minimum followup was 3 months (average, 32 months; range, 3–118 months). Sixteen patients (94%) had clinical and radiographic evidence of healing at an average of 99 days (range, 43–229 days). Major complications occurred in four patients; one had a persistent nonunion, two had wound infections, and one underwent resection of the distal fibula for subsequent development of fibulotalar arthrosis after ankle arthrodesis. Minor complications occurred in two patients, one tendinitis and one persistent malunion. There were no complications at the iliac crest bone graft site. Autogenous iliac crest tricortical bone grafts, when used in conjunction with correction of alignment and stable internal fixation, are a reasonable option for treatment of nonunions and malaligned nonunions of the tibia and fibula.,[object Object]

Modified Pauwels’ Intertrochanteric Osteotomy in Neglected Femoral Neck Fracture

Narender Kumar Magu MS (Ortho), MAMS, Rajesh Rohilla MS (Ortho), Roop Singh MS (Ortho), Rochak Tater MS (Ortho) Many reported treatment methods for neglected femoral neck fractures do not always satisfactorily address nonunion, coxa vara, and limb shortening. We retrospectively reviewed the functional outcome of the modified Pauwels’ intertrochanteric osteotomy in 48 adults (mean age, 48.1 years) to determine whether this approach would correct those problems. The average preoperative limb shortening was 2.7 cm (range, 1.5–5 cm) in 38 patients and mean neck-shaft angle was 107.3° (range, 80°–120°). The minimum followup was 2 years (mean, 6.1 years; range, 2–16.5 years). Union was achieved in 44 of the 48 patients. Union also was achieved in two of the four nonunions after revision osteotomy. Postoperative avascular necrosis of the femoral head developed in two of the 48 patients after an average followup of 6 years. Limb-length equalization was achieved in 40 (83%) patients and 40 had near-normal gait. The average neck-shaft angle at the final followup was 132.7° (range, 120°–155°). The average Harris hip score was 86.7 points and Merle d’Aubigné-Postel score was 14.1. We believe the primary modified Pauwels’ intertrochanteric osteotomy is a reliable alternative to achieve fracture healing in neglected femoral neck fractures and simultaneously correct associated coxa vara and shortening. A two-stage surgical incision makes the procedure simple and less demanding.,[object Object]

Are Current Measurements of Lower Extremity Muscle Architecture Accurate?

Samuel R. Ward PT, PhD, Carolyn M. Eng BS, Laura H. Smallwood BS, PA, Richard L. Lieber PhD Skeletal muscle architecture is defined as the arrangement of fibers in a muscle and functionally defines performance capacity. Architectural values are used to model muscle-joint behavior and to make surgical decisions. The two most extensively used human lower extremity data sets consist of five total specimens of unknown size, gender, and age. Therefore, it is critically important to generate a high-fidelity human lower extremity muscle architecture data set. We disassembled 27 muscles from 21 human lower extremities to characterize muscle fiber length and physiologic cross-sectional area, which define the excursion and force-generating capacities of a muscle. Based on their architectural features, the soleus, gluteus medius, and vastus lateralis are the strongest muscles, whereas the sartorius, gracilis, and semitendinosus have the largest excursion. The plantarflexors, knee extensors, and hip adductors are the strongest muscle groups acting at each joint, whereas the hip adductors and hip extensors have the largest excursion. Contrary to previous assertions, two-joint muscles do not necessarily have longer fibers than single-joint muscles as seen by the similarity of knee flexor and extensor fiber lengths. These high-resolution data will facilitate the development of more accurate musculoskeletal models and challenge existing theories of muscle design; we believe they will aid in surgical decision making.

Extremely Small-magnitude Accelerations Enhance Bone Regeneration: A Preliminary Study

Soon Jung Hwang MD, DDS, Svetlana Lublinsky MS, Young-Kwon Seo PhD, In Sook Kim PhD, Stefan Judex PhD High-frequency, low-magnitude accelerations can be anabolic and anticatabolic to bone. We tested the hypothesis that application of these mechanical signals can accelerate bone regeneration in scaffolded and nonscaffolded calvarial defects. The cranium of experimental rats (n = 8) in which the 5-mm bilateral defects either contained a collagen scaffold or were left empty received oscillatory accelerations (45 Hz, 0.4 g) for 20 minutes per day for 3 weeks. Compared with scaffolded defects in the untreated control group (n = 6), defects with a scaffold and subject to oscillatory accelerations had a 265% greater fractional bone defect area 4 weeks after the surgery. After 8 weeks of healing (1-week recovery, 3 weeks of stimulation, 4 weeks without stimulation), the area (181%), volume (137%), and thickness (53%) of the regenerating tissue in the scaffolded defect were greater in experimental than in control animals. In unscaffolded defects, mechanical stimulation induced an 84% greater bone volume and a 33% greater thickness in the defect. These data provide preliminary evidence that extremely low-level, high-frequency accelerations can enhance osseous regenerative processes, particularly in the presence of a supporting scaffold.

Articular Cartilage Increases Transition Zone Regeneration in Bone-tendon Junction Healing

Margaret Wan Nar Wong FRCS, Ling Qin PhD, Kwong Man Lee PhD, Kwok Sui Leung MD The fibrocartilage transition zone in the direct bone-tendon junction reduces stress concentration and protects the junction from failure. Unfortunately, bone-tendon junctions often heal without fibrocartilage transition zone regeneration. We hypothesized articular cartilage grafts could increase fibrocartilage transition zone regeneration. Using a goat partial patellectomy repair model, autologous articular cartilage was harvested from the excised distal third patella and interposed between the residual proximal two-thirds bone fragment and tendon during repair in 36 knees. We evaluated fibrocartilage transition zone regeneration, bone formation, and mechanical strength after repair at 6, 12, and 24 weeks and compared them with direct repair. Autologous articular cartilage interposition resulted in more fibrocartilage transition zone regeneration (69.10% ± 14.11% [mean ± standard deviation] versus 8.67% ± 7.01% at 24 weeks) than direct repair at all times. There was no difference in the amount of bone formation and mechanical strength achieved. Autologous articular cartilage interposition increases fibrocartilage transition zone regeneration in bone-tendon junction healing, but additional research is required to ascertain the mechanism of stimulation and to establish the clinical applicability.

Case Report: The Prone Reduction of a Sacroiliac Disruption with a Pelvic C-clamp

Andres Javier Quintero MD, Ivan S. Tarkin MD, Hans-Christoph Pape MD The pelvic C-clamp traditionally is reserved for the temporizing stabilization of posterior ring injuries and reportedly has assisted in closed reduction of sacroiliac diastases, for patients who are in the supine position. We report a patient with a severely displaced Zone II sacral fracture and associated acetabular fracture who initially underwent fixation of the acetabulum in the prone position. By using the pelvic C-clamp as a tool for successfully reducing the sacrum, definitive closed fixation of the pelvic wing subsequently was performed without having to reposition the patient. In this case report, we review the literature on this device and for alternative reduction maneuvers for disrupted sacral injuries. The C-clamp may be a useful adjunct in select cases to facilitate closed reduction of sacral or sacroiliac joint disruptions, as may particularly apply in cases of severe displacement or when a reduction is hampered by obesity.

Case Reports: Tantalum Debris Dispersion During Revision of a Tibial Component for TKA

Jose Miguel Sanchez Marquez MD, Nicolas Del Sel MD, Alejandro Leali MD, Alejandro González Della Valle MD Porous tantalum nonmodular tibial components for TKA were introduced in 1999. We revised three well-fixed tantalum tibial trays. For removal, we used osteotomes and revision oscillating saw blades. Removal of the components was laborious and resulted in generation of abundant tantalum debris that seeded the periarticular soft tissues despite meticulous protection with gauze. The retained metallic debris that is visible on postoperative radiographs has the potential for generation of third-body wear. We alert the orthopaedic community about this phenomenon and recommend minimizing the use of motorized revision instruments for removal of trabecular metal implants.
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