Glenohumeral Cartilage Thickness: Implications in Prosthetic Design and Osteochondral Allograft Transplantation.

OBJECTIVE: A complete understanding of the glenohumeral joint anatomy is crucial for osteochondral allograft (OCA) transplantation and prosthetic design. However, existing data on the cartilage thickness distribution are not consistent. This study aims to describe the cartilage thickness distribution at both the glenoid cavity and humeral head in males and females. DESIGN: Sixteen fresh cadaveric shoulder specimens were dissected and separated to expose the glenoid and humeral head articular surfaces. The glenoid and humeral head were cut into 5-mm coronal sections. Sections were imaged and cartilage thickness was measured at 5 standardized points on each section. Measurements were analyzed based on age, sex, and regional location. RESULTS: For the humeral head, cartilage was thickest centrally (M = 1.77 ± 0.35 mm) and thinnest superiorly and inferiorly (M = 1.42 ± 0.37 mm, 1.42 ± 0.29 mm). At the glenoid cavity, cartilage was thickest in the superior and inferior areas (M = 2.61 ± 0.47 mm, 2.53 ± 0.58 mm) and thinnest centrally (M = 1.69 ± 0.22 mm). Males were found to have thicker cartilage at both the humeral head and glenoid (P = 0.0014, P = 0.0133). CONCLUSIONS: Articular cartilage thickness distribution of the glenoid and humeral head is nonuniform and reciprocal in nature. These results can be used to further inform prosthetic design and OCA transplantation. We noted a significant difference in cartilage thickness between males and females. This suggests that the sex of the patient should be taken into consideration when matching donors for OCA transplantation.

Optimal configuration for stability and magnetic resonance imaging quality in temporary external fixation of tibial plateau fractures.

INTRODUCTION: Temporary external fixation has been widely utilized in the stabilization of plateau fractures while waiting for an optimization of the soft tissue conditions before subsequent permanent internal fixation. Simultaneously, MRI is beneficial in the assessment of concomitant damage to ligaments and menisci so that these injuries could be promptly identified, and surgical planning executed at the time of definitive fixation of the bony injury. Increasing numbers of side-bars and pins have been previously suggested to increase frame rigidity, but at the same time, several studies have indicated the presence of MRI artifacts which may obscure key anatomical structures, even when MRI-compatible fixation devices are used. This study aims to identify, among six potential configurations, the construct that maximizes stability while most minimizing the number of MRI artifacts generated among different configurations commonly used. HYPOTHESIS: There is one or more configurations among the others that maximize stability while preserving a clinically acceptable level of MRI quality. MATERIAL AND METHODS: Six constructs were recreated on cadaveric specimens and identified by the disposition of the bars: H, Anterior, Flash, Hashtag, Rhomboid, and Diamond. Stage one evaluated the amount of artifact produced during MRI on instrumented cadaveric legs, as well as the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) at five specific regions of interest. Stage two assessed the amount of compressional and torsional stiffness of the configurations on bone surrogate models. RESULTS: Image artifacts were not detected within the knee joint for all considered constructs. In terms of SNR The H, Anterior, Hashtag, and Diamond configurations were not significantly different from their control (p>0.366) while the others were significantly different (p<0.03). The values of CNR found for the H and Hashtag configurations were not significantly different from their controls (p>0.07) while the remaining configurations were significantly different (p<0.03). In compression, the H and Diamond configurations had similar stiffness (p=0.468) of 35.78N/mm and 31.44N/mm, respectively, and were stiffer than the other configurations. In torsion, the constructs have shown different stiffness (p<0.001) with a minimum value of 0.66 Nm/deg for the Rhomboid configuration, which was significantly less stiff than the Anterior configuration (1.20 Nm/deg [p<0.001]). There was no difference between the Diamond and H configurations (p=0.177) or between them and the Hashtag configuration (p=0.215). DISCUSSION: An external fixator construct directly bridging the femur and tibia without interconnections is the most stable and produces MRI scans without image artifacts that would interfere with diagnostic quality. LEVEL OF EVIDENCE: V, basic science study, diagnostic imaging and mechanical testing.

Cost and Complications of Percutaneous Fixation of Hand Fractures in a Procedure Room Versus the Operating Room.

BACKGROUND: The purpose of this study was to compare closed reduction and percutaneous pinning of metacarpal and phalanx fractures performed in the operating room (OR) versus the procedure room of the emergency department with primary outcomes being infection rate, radiographic union, and monetary cost. METHODS: From January 2006 to December 2010, all closed reduction and percutaneous pinnings of metacarpal and phalanx fractures (CPT codes: 26608; 26727) by a single board-certified hand surgeon (A.M.H.) were retrospectively reviewed. Patients were placed into 2 groups: Group 1 was patients treated in the OR, and group 2 was patients in an emergency department procedure room. Infection, malunion, and nonunion rates were compared using a chi-square test. Charges were compared using a t-test, and cost of supplies and labor was evaluated. RESULTS: A total of 189 patients met final inclusion criteria for this study: 130 in group 1 and 59 in group 2. There was no statistically significant difference in infection rates ( P = .13), nonunion ( P = .40), malunion rates ( P = .89), and hardware failure with revision ( P = .94) between the 2 groups. The procedure room patients had an average hospital charge of $1358.55 compared with $3691.85 for OR-treated patients (P = .001). The total cost of supplies and nonphysician labor was $432.31 per OR case and $179.59 per procedure room case. CONCLUSIONS: Metacarpal and phalanx fractures of the hand amendable to closed reduction and percutaneous pinning can be treated in the procedure room with no increase in risk of infection, malunion, or nonunion rates. In addition, these surgeries can be performed in a procedure room with lower cost and less charges to patients than in the operating room.