Accuracy of measurement of Hill-Sachs lesions with computed tomography.

BACKGROUND: Bone defects play a role in recurrent instability. There is no universal method to quantify humeral head defects. The purpose of this study is to assess the accuracy of 2-dimensional computed tomography (CT) scan measurements of Hill-Sachs lesions. MATERIALS AND METHODS: Six Hill-Sachs defects were created in anatomically shaped bone substitutes. The samples were scanned with a 3-dimensional laser scanner. Maximum width and depth were measured and used as the true measurement. The samples underwent routine CT scanning, and 5 physicians measured maximum width and depth on each plane independently. The intraclass correlation coefficient (ICC) was used to assess agreement. Percent error and paired t test were used for statistical analysis (P < .05 denoted significance). RESULTS: The ICC between observers was 0.879 (95% confidence interval, 0.780-0.946) and 0.721 (95% confidence interval, 0.543-0.865) for the depth and width measurement, respectively. The ICC was good between individual observers and the true measurement (range, 0.765-0.956). Individual observers were more accurate in depth rather than width measurements. The mean overall percent error of the depth and width measurements for the 6 defects was calculated: coronal, 19.2% ± 13.6%; sagittal, 11.8% ± 8.2%; and axial, 13.6% ± 8.4%. CONCLUSIONS: The depth of Hill-Sachs lesions can be reliably assessed using CT scan. Observers consistently underestimated width in all imaging planes. Overall, sagittal- and axial-plane measurements are more accurate for evaluation of these defects than the coronal plane. Future studies using 3-dimensional CT may be helpful to further quantitatively assess the size of the Hill-Sachs lesion, including width and volume.

Anterior knee pain in the young athlete: diagnosis and treatment.

The underlying etiology of anterior knee pain has been extensively studied. Despite many possible causes, often times the diagnosis is elusive. The most common causes in the young athlete are osteosynchondroses, patellar peritendinitis and tendinosis, synovial impingement, malalignment, and patellar instability. Less common causes are osteochondritis dissecans and tumors. It is always important to rule out underlying hip pathology and infections. When a diagnosis cannot be established, the patient is usually labeled as having idiopathic anterior knee pain. A careful history and physical examination can point to the correct diagnosis in the majority of cases. For most of these conditions, treatment is typically nonoperative with surgery reserved for refractory pain for an established diagnosis.

Computer-assisted surgery for anterior cruciate ligament reconstruction.

Anterior cruciate ligament (ACL) reconstruction is one of the most common orthopedic procedures. Revision rates are as high as 40% with malpositioned tunnels as a chief contributor. Computer-assisted orthopedic surgery or navigation for ACL reconstruction has been introduced to help decrease the revision rate. We review the role of computer navigation in improving the accuracy of tunnel placement, assessing kinematics of the knee, and in training surgeons to correctly perform ACL reconstructions. We report on our experience with navigated ACL reconstruction and describe the kinematic evaluation of a series of patients who underwent the procedure.

A citric acid-based hydroxyapatite composite for orthopedic implants.

We describe a novel approach to process bioceramic microparticles and poly(diol citrates) into bioceramic-elastomer composites for potential use in orthopedic surgery. The composite consists of the biodegradable elastomer poly(1,8-octanediol-citrate) (POC) and the bioceramic hydroxyapatite (HA). The objective of this work was to characterize POC-HA composites and assess the feasibility of fabricating tissue fixation devices using machining and molding techniques. The mechanical properties of POC-HA composites with HA (40, 50, 60, 65wt.%) were within the range of values reported for tissue fixation devices (for POC-HA 65wt.%, S(b)=41.4+/-3.1, E(b)=501.7+/-40.3, S(c)=74.6+/-9.0, E(c)=448.8+/-27.0, S(t)=9.7+/-2.3, E(t)=334.8+/-73.5, S(s)=27.7+/-2.4, T(s)=27.3+/-4.9, all values in MPa). At 20 weeks, the weight loss of POC-HA composites ranged between 8 and 12wt.%, with 65wt.% HA composites degrading the slowest. Exposure of POC-HA to simulated body fluid resulted in extensive mineralization in the form of calcium phosphate with Ca/P of 1.5-1.7 similar to bone. POC-HA supported osteoblast adhesion in vitro and histology results from POC-HA samples that were implanted in rabbit knees for 6 weeks suggest that the composite is biocompatible. Synthesis of POC-HA is easy and inexpensive, does not involve harsh solvents or initiators, and the mechanical properties of POC-HA with 65wt.% HA are suitable for the fabrication of potentially osteoconductive bone screws.

Anterior cruciate ligament (ACL) tunnel placement: a radiographic comparison between navigated versus manual ACL reconstruction.

As participation in sports has increased, so have anterior cruciate ligament (ACL) reconstructions. The procedure is commonly associated with inaccurate tunnel placements, even when performed by experienced surgeons. Computer-assisted surgery may assist in eliminating inconsistent graft tunnels by increasing precision and providing navigation feedback of the surgical field. This study aimed to compare the accuracy of tunnel placements between computer-navigated and manual ACL reconstructions using radiography. Results suggest that the two methods have comparable accuracy but that the use of additional imaging techniques is recommended during tunnel placement evaluation.