Symmetry-preserving modeling for lithographic imaging.

In computational imaging and lithography, it has been a challenge for a numerical model to faithfully preserve symmetries in the physical imaging system. In this Letter, we present a project-to-symmetry-subspace (PTSS) method to prevent symmetry loss during the iterative generation of optical kernels. Essentially, PTSS is to project iterative vectors onto a predefined symmetric subspace when decomposing the transmission cross coefficient (TCC). Simulation results demonstrate the PTSS-generation of a truncated set of optical kernels that are substantially free of symmetry error, regardless of the order of truncation.

Private Equity: An Emerging Practice Model.

Private equity acquisitions are increasing among orthopedic practices. The concepts and vocabulary surrounding these deals may be foreign to physicians. There are both potential risks and potential benefits to physicians at the center of these complex deals, and a clear understanding of any proposed private equity acquisition is crucial. Short-term data on private equity acquisition in other procedure-based outpatient specialties have shown that private equity ownership consistently increased the number of patients seen per provider, allowed amount per claim, and utilization of advanced practice practitioners. These studies did not show consistent changes in the rates of invasive procedures or negative impacts on patient care. Each practice will need to carefully consider any potential private equity involvements.

Risk Factors for Skin Tears Following Collagenase Clostridium histolyticum to Treat Dupuytren Contractures.

PURPOSE: Skin tears are an unpleasant complication that may occur after collagenase Clostridium histolyticum (CCH) administration to treat Dupuytren contractures of the fingers. The purpose of this study was to determine risk factors for the development of this complication. METHODS: Over a 6-year period, patients with a measurable metacarpophalangeal or proximal interphalangeal joint Dupuytren contracture and a palpable cord treated with CCH were prospectively observed. Patients were assessed for the development of skin tears immediately on the day of manipulation as well 30 days or more after manipulation. RESULTS: A total of 117 patients (174 cords) met inclusion criteria. There was a 25.6% incidence of skin tears (30 of 117 patients; 33 skin tears). Multivariable regression analysis revealed that patients with a combined digital flexion contracture (total combined metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joint contracture) of 75° and greater and those treated with 2 simultaneous doses of CCH in the same hand were more likely to sustain a tear. All skin tears healed with nonsurgical management at short-term follow-up. CONCLUSIONS: Although a relatively minor complication, skin tears are not well-tolerated by all patients and may change the postinjection course of orthosis use, wound care, and manual activity. Based on these results, patients with digital contractures 75° or greater and those treated with 2 simultaneous doses of CCH in the same hand may be counseled that they have a higher likelihood of developing a skin tear during manipulation. Pretreatment education may reduce anxiety experienced by patients who otherwise unexpectedly develop a skin tear at the time of manipulation. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic II.

The Use of Contact Biomechanics to Study the Intact, Proximal Row Carpectomy and Scaphoid Excision, Four Bone Fusion Wrist.

The study of contact biomechanics of the wrist is a challenge. This is partly due to the relatively small size of the joint as well as the lack of space in the radiocarpal joint which makes the delivery of investigative materials such as pressure sensitive film without causing artifact, difficult. Fortunately, a number of authors have studied the intact wrist, the scapholunate ligament injured wrist, the proximal row carpectomy and the scaphoid excision, four bone fusion. Despite some contrasting findings, there are some general concepts that we understand about wrist mechanics.

Optimization of Anterior Incision Placement for Distal Biceps Repair.

Introduction Damage to the posterior interosseous nerve (PIN) is a known complication when using a cortical button during distal biceps tendon repair. Prior studies show that the trajectory of the drill through the biceps tuberosity can affect the distance from the PIN. We develop a mathematical model to predict the location of the tuberosity based on a palpable bony landmark and patient demographic factors. Methods The medical charts and elbow radiographs of (n = 82) adult patients were retrospectively reviewed. Using standard radiographic software, two observers measured the distance from the olecranon tip to the center of the biceps tuberosity. Multivariate regression analysis was used to build a linear model. The model was cross-validated with five arms from three distinct cadavers. A surgical wire was guided into the volar aspect of each forearm using the model, and a dissection was then performed to assess the proximity of the surgical wire to the insertion of the biceps tendon on the radial tuberosity. Results Olecranon-tuberosity distance (OTD) ranged from 52.3 mm to 77.2 mm (mean 66.5 mm). Univariate analyses revealed males had significantly longer OTD (mean 69.3 mm) compared to females (mean 61.2 mm, t-test, p < 0.001). Increased body mass index (BMI) weakly correlated with increased distance (Pearson's r = 0.22, p = 0.048). Height showed strong positive correlation with increased distance (r = 0.77, p < 0.001). Multivariate regression revealed that significant predictive factors for olecranon-tuberosity distance were height (coefficient = 35.8, p < 0.001), BMI (coefficient = 0.14, p = 0.032), and male sex (coefficient = 3.17, p = 0.0039). The average error in the cadaveric validation, measured as distance from the surgical wire to the distal biceps insertion was 1.8 mm. Conclusion A highly accurate mathematical model can be used to predict the location of the biceps tuberosity in relation to the palpable tip of the olecranon, based only on height, BMI, and sex of the patient. Knowledge of this distance can guide accurate placement of the skin incision when a transverse single-incision approach is utilized for repair of the distal biceps tendon using a cortical button. Diagnostics showed the model to be less accurate near the extremes of the measurement. Since patients with a target incision point far removed from average would most benefit from such a model, we will continue by identifying and enrolling patients at the low and high ends of the range. We further hypothesize that the technique described above could be similarly applied to benefit other procedures.

Total Wrist Arthrodesis: Indications and Clinical Outcomes.

Total wrist arthrodesis remains an important technique in the surgical armamentarium of upper extremity surgeons. The procedure has evolved over time but continues to provide reliable pain relief at the expense of wrist motion. It is indicated for management of a wide variety of upper extremity conditions, including rheumatoid arthritis, posttraumatic osteoarthritis, cerebral palsy, and brachial plexus injuries, and as a salvage technique after failed implant arthroplasty. Recent studies demonstrate high levels of patient satisfaction and good functional outcomes after bilateral wrist fusion. Compared with total wrist arthroplasty, total wrist arthrodesis provides more reliable pain relief with lower rates of complications, but further studies are needed to compare functional outcomes and cost-effectiveness.

Superficialis Sling (Flexor Digitorum Superficialis Tenodesis) for Swan Neck Reconstruction.

Swan neck deformity, or hyperextension of the proximal interphalangeal joint, may occur secondary to trauma, rheumatoid arthritis, cerebral palsy, or Ehlers-Danlos syndrome, and can be treated with tenodesis of one slip of the flexor digitorum sublimis tendon. This technique has several variations, differing primarily in the specific location and method that a single slip of the flexor digitorum sublimis tendon is secured, but they all serve to create a static volar restraint against hyperextension. Options include tunneling the tendon through the bone of the proximal phalanx, attaching the tendon to the A1 or A2 pulley, or securing the tendon with bone anchors in the proximal phalanx.

Improving Value in Musculoskeletal Care Delivery: AOA Critical Issues.

Improving value in musculoskeletal health care has emerged as an important objective in both the United States and Canada. In order to achieve this objective, providers need to have a clear definition of value and an infrastructure for measuring outcomes of interest to patients and costs over the episode of care. Although national patient registries have been established in the United States and Canada, they nevertheless lag behind other registries worldwide in terms of collecting patient-reported outcomes and capturing data from a wide cross-section of hospitals and physicians. With the help of professional medical societies and the creation of national initiatives, patient-reported outcomes data collection on a large scale may be possible, but many challenges remain regarding implementation. Alternatives to the fee-for-service payment model, including pay-for-reporting and pay-for-performance, may help incentivize physicians and health-care providers to obtain and improve on patient-reported outcomes data collection. Other payment reforms, such as bundled payments, have been piloted in certain regions, but their sustainability and long-term success are unclear at this time. Novel health-care delivery strategies aimed at improving quality, coordinating multispecialty care, and enhancing patient participation in shared decision-making have shown promise in improving patient-centered outcomes, but delivery models continue to vary greatly throughout the United States and Canada. The current status of musculoskeletal health-care delivery requires substantial change before the goal of improving patient outcomes and lowering health-care costs can be achieved.

Dorsal surgical approaches to the proximal interphalangeal joint: a comparative anatomic study.

PURPOSE: Adequate exposure of the articular surface of the head of the proximal phalanx is essential for reduction of intra-articular fractures of the proximal interphalangeal (PIP) joint. We compared the articular exposure obtained by a dorsal extensor-tendon splitting (Swanson), an extensor tendon-reflecting (Chamay), and an extensor mechanism-sparing approach. METHODS: The PIP joints of 24 digits from 6 fresh-frozen cadaveric specimens were randomly assigned to 1 of 3 dorsal surgical exposures: an extensor tendon-splitting, extensor tendon-reflecting, or extensor mechanism-sparing approach. The exposed surface was painted with methylene blue and the PIP joints were disarticulated to reveal the distal articular surface of the proximal phalanx. Using 3-dimensional digital mapping, we calculated the percentage of the exposed dyed surface area to the total surface area and compared the 3 approaches. RESULTS: The mean percent exposed joint surface area for the extensor tendon-splitting, extensor tendon-reflecting, and extensor mechanism-sparing approaches were 41%, 52%, and 16%, respectively. Each approach provided a significantly different percentage of articular PIP joint surface area from the other 2. CONCLUSIONS: The amount of articular surface visualized using 3 dorsal approaches to the PIP joint must be weighed against the amount of extensor mechanism violated. Exposure of the articular surface by the extensor mechanism-sparing approach to the PIP joint allowed nearly a third of the exposure gained by the extensor tendon-reflecting exposure. Although the extensor tendon-reflecting technique revealed the greatest amount of surface, nearly 50% of the proximal phalanx articular surface remained inaccessible as long as the collateral ligaments were intact. CLINICAL RELEVANCE: Understanding the limitations inherent in dorsal exposure of the PIP joint may help guide the surgical approach for the individual patient.

High-pressure injection injuries to the hand.

The severity of high-pressure injection injuries to the hand is often underappreciated on initial presentation. These injuries require urgent and thorough surgical débridement. Despite the advances in our understanding of this injury type and the decline in amputation rates, the risk of long-term morbidity with diminished function and chronic symptoms remains high, and the role of systemic steroids in treatment is uncertain. Functional outcome of the hand and upper extremity following high-pressure injection injuries depends on a number of factors, including the magnitude of the initial wounding force, the chemical properties and volume of the substance injected, the presence of secondary infection, and the timing and thoroughness of débridement. Further investigation is required to determine the relative significance of these factors and the effectiveness of steroids in treatment.

Scaphoid excision and 4-bone arthrodesis versus proximal row carpectomy: a comparison of contact biomechanics.

PURPOSE: We compare scaphoid excision and 4-bone arthrodesis (FBA) with proximal row carpectomy (PRC) in terms of contact pressure, area, and location. METHODS: Six cadaveric forearms underwent simulated FBA with K-wires. We measured pressures in the radiocarpal joint with Fuji contact film after we applied a 200-N load via the wrist tendons with the wrist in neutral, flexion, and extension. We repeated the experiment after excising the lunate and triquetrum, to create a PRC in the same specimens. RESULTS: Contact pressure in the PRC wrist was significantly greater, by 25%, compared with the FBA wrist for all wrist positions. The PRC wrist had a significantly smaller contact area, by 43%, compared with the FBA wrist. In the FBA wrist, lunate contact was more dorsal in flexion but more volar in extension. In the PRC wrist, capitate contact was more dorsal and radial in flexion, whereas the contact was more volar and ulnar in extension. Comparing contact location, FBA contact was significantly more ulnar than PRC contact in wrist flexion. We found no significant difference in contact translation (the distance between the contact locations in the positions of wrist flexion and extension) for the lunate in FBA or the capitate in PRC. CONCLUSIONS: The FBA wrist has significantly lower contact pressure (P < .001), greater contact area (P < .001), and equal contact translation compared with the PRC wrist. These qualities may make FBA less susceptible to degeneration over time. By advancing our understanding of the biomechanics of both wrist procedures, we may better tailor them to the individual patient. CLINICAL RELEVANCE: Current biomechanical evidence is lacking for common motion-preserving procedures for wrist arthritis. Comparing contact pressure, area, and location provides a biomechanical basis of our clinical understanding of these surgeries.

External fixation versus internal fixation for unstable distal radius fractures: a systematic review and meta-analysis of comparative clinical trials.

OBJECTIVES: There is no consensus on the surgical management of unstable distal radius fractures. In this systematic review and meta-analysis, we pool data from trials comparing external fixation and open reduction and internal fixation (ORIF) for this injury. DATA SOURCES: We searched electronic databases (including MEDLINE, EMBASE, and SCOPUS) and conference proceedings from 1950 to 2009 in the English literature. STUDY SELECTION: We pooled data from 12 trials totaling 1011 patients (491 fractures treated with external fixation and 520 with ORIF). All randomized studies of external fixation to ORIF for unstable distal radius fractures were considered, and nonrandomized trials were included if and only if they directly compared external fixation with ORIF. DATA EXTRACTION: Two authors independently extracted data from all eligible studies, including patient characteristics, sample size, fracture type, length of follow-up, intervention, and outcomes. DATA SYNTHESIS: Continuous variables were pooled across studies using the method of standard mean differences (SMD) or effect size. ORIF demonstrated significantly better Disabilities of the Arm, Shoulder, and Hand scores (SMD, 0.28; 95% confidence interval, 0.03-0.53; P = 0.03), recovery of forearm supination (SMD, 0.23; 95% CI, 0.08-0.38; P = 0.003), and restoration of volar tilt (SMD, 0.53; 95% CI, 0.34-0.72; P < 0.00001). However, external fixation resulted in significantly better grip strength (SMD, -10.32; 95% CI, -16.36 to -4.28; P = 0.0008), and subgroup analyses of randomized studies showed external fixation yielded better wrist flexion (SMD, -0.38; 95% CI, -0.58 to -0.17; P = 0.0004). CONCLUSIONS: For surgical fixation of unstable distal radius fractures, ORIF yields significantly better functional outcomes, forearm supination, and restoration of anatomic volar tilt. However, external fixation results in better grip strength, wrist flexion, and remains a viable surgical alternative. LEVEL OF EVIDENCE: Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

Unstable distal radial fractures treated with external fixation, a radial column plate, or a volar plate. A prospective randomized trial.

BACKGROUND: Optimal surgical management of unstable distal radial fractures is controversial, and evidence from rigorous comparative trials is rare. We compared the functional outcomes of treatment of unstable distal radial fractures with external fixation, a volar plate, or a radial column plate. METHODS: Forty-six patients with an injury to a single limb were randomized to be treated with augmented external fixation (twenty-two patients), a locked volar plate (twelve), or a locked radial column plate (twelve). The fracture classifications included Orthopaedic Trauma Association (OTA) types A3, C1, C2, and C3. The patients completed the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire at the time of follow-up. Grip and lateral pinch strength, the ranges of motion of the wrist and forearm, and radiographic parameters were also evaluated. RESULTS: At six weeks, the mean DASH score for the patients with a volar plate was significantly better than that for the patients treated with external fixation (p = 0.037) but similar to that for the patients with a radial column plate (p = 0.33). At three months, the patients with a volar plate demonstrated a DASH score that was significantly better than that for both the patients treated with external fixation (p = 0.028) and those with a radial column plate (p = 0.027). By six months and one year, all three groups had DASH scores comparable with those for the normal population. At one year, grip strength was similar among the three groups. The lateral pinch strength of the patients with a volar plate was significantly better than that of the patients with a radial column plate at three months (p = 0.042) and one year (p = 0.036), but no other significant differences in lateral pinch strength were found among the three groups at the other follow-up periods. The range of motion of the wrist did not differ significantly among the groups at any time beginning twelve weeks after the surgery. At one year, the patients with a radial column plate had maintained radial inclination and radial length that were significantly better than these measurements in both the patients treated with external fixation and those with a volar plate (all p < 0.05). CONCLUSIONS: Use of a locked volar plate predictably leads to better patient-reported outcomes (DASH scores) in the first three months after fixation. However, at six months and one year, the outcomes of all three techniques evaluated in this study were found to be excellent, with minimal differences among them in terms of strength, motion, and radiographic alignment.