Demographic Data Reliably Predicts Total Hip Arthroplasty Component Size.

BACKGROUND: Preoperative radiographic templating for total hip arthroplasty (THA) has been shown to be inaccurate, although essential for streamlining operating room efficiency. Although demographic data have shown to predict total knee arthroplasty component sizes, the unique contour and design among femoral stem implants have limited a similar application for hip arthroplasty. The purpose of this study was to determine whether demographic data may predict cementless THA size independent of the stem design. METHODS: A consecutive series of 1,653 index cementless metaphyseal-fitting THAs were reviewed between 2007 and 2019. This included 12 unique femoral component designs, 6 acetabular component designs, 60 femur size-design combinations, and 23 acetabular size-design combinations. Implanted component sizes and patient demographic data were collected, including gender, height, weight, laterality, age, race, and ethnicity. Multivariate linear regressions were formulated to predict implanted femur and acetabular component sizes from the demographic data. RESULTS: There was a significant linear correlation between gender, implant model, age, height, and weight for femur (R2 = 0.778; P < .001) and acetabular (R2 = 0.491; P < .001) sizes. Calculated femur and acetabular component sizes averaged within 0.97 and 0.95 sizes of those implants, respectively. Femur and acetabular sizes were predicted within 1 size 79.1% and 78.2% and within 2 sizes 94.3% and 94.6% of the time, respectively. CONCLUSIONS: Multivariate regression models were created based on specific demographics data to predict femur and acetabular component sizes. The model allows for simplified preoperative planning and potential cost savings implementation. A free phone application named EasyTJA was constructed for ease of implementation.

The area method for measuring acetabular cup anteversion: An accurate and autonomous solution.

Several radiological methods of measuring anteversion of the acetabular component after total hip arthroplasty have been described, all time-consuming and with varying reproducibility. This study aimed to compare the recently proposed Area method to true cup anteversion as determined by an accelerometer. This study further applied this method programmatically to autonomously determine radiographic cup orientation using two computer programs, then compared these results to hand and accelerometer measurements. 160 anteroposterior pelvis radiographs were taken of a standard Sawbones® pelvis fitted with a total hip arthroplasty system. The acetabular cup was re-oriented between each radiograph, with anteversion ranging from 0° to 90°. An accelerometer was mounted to the cup to measure true cup anteversion. Radiographic anteversion was independently measured via three methods: by hand, linear image processing, and machine learning. Measurements were compared to triaxial accelerometer recordings. Coefficient of determination (R2) was found to be 0.997, 0.991, and 0.989 for hand measurements, the machine learning, and linear image processing, respectively. The machine learning program and hand measurements overestimated anteversion by 0.70° and 0.02° respectively. The program using linear techniques underestimated anteversion by 5.02°. Average runtime was 0.03 and 0.59 s for the machine learning and linear image processing program, respectively. The machine learning program averaged within 1° of cup orientation given a true cup anteversion less than 51°, and within 2° given an anteversion less than 85°. The Area method showed great accuracy and reliability with hand measurements compared to true anteversion. The results of this study support the use of machine learning for accurate, timely, autonomous assessment of cup orientation.

Characterising acetabular component orientation with pelvic motion during total hip arthroplasty.

INTRODUCTION: Suboptimal acetabular component position can result in impingement, dislocation, and accelerated wear. Intraoperative pelvic motion has led to surgeon error and acetabular cup malposition. This study characterises the relationship between pelvic rotation and postoperative acetabular cup orientation. METHODS: A device was constructed to allow cadaveric pelvis rotation along three axes about an acetabular cup in fixed orientation. The acetabular cup was fixed in space at 40° of radiographic inclination and 15° of anteversion relative to the anterior pelvic plane to represent consistent surgeon intraoperative placement. Active marker clusters were fixed to surgical equipment while the cadaveric pelvis was cemented with passive reflective markers, both identified with the Optotrak Certus motion capture system. The reamed cadaveric pelvis was rotated along three axes from -45° to 45° of roll, -30° to 30° of tilt, and -35° to 35° of pitch. The change in component inclination and anteversion was recorded at each 5° interval. Using computed tomography 3D reconstruction, the experimental setup was duplicated computationally to assess against a greater range of pelvis and implant sizes. RESULTS: Radiographic anteversion and inclination showed a non-linear relationship dependent on pelvic roll, tilt, and pitch. Radiographic anteversion changed -0.59°, 0.76° and 0.01° while radiographic inclination changed 0.23°, 0.18° and 1.00° for every 1° of pelvic roll, tilt and pitch, respectively. Computationally, anteversion changed -0.61°, 0.75° and 0.00° while inclination changed 0.22°, 0.19° and 1.00° for every 1° of pelvic roll, tilt and pitch, respectively. These results were independent of cup and pelvis size. CONCLUSIONS: Intraoperative pelvic motion can significantly affect final cup position, and this should be accounted for when placing acetabular components during total hip arthroplasty. Based on this study, intraoperative adjustment of the acetabular component position based on pelvis motion may be implemented to improve postoperative component position.

Complications of total joint arthroplasty in solid organ transplant patients versus a large control group.

BACKGROUND: Solid organ transplant patients are theoretically at increased risk for complications after total joint replacement due to immunosuppressive medication regimens and multiple medical co-morbidities. There are a number of studies that report on outcomes of total joint arthroplasty (TJA) following solid organ transplant, however, the results are heterogeneous. This study evaluated the outcomes of TJA in solid organ transplant patients as compared to non-organ transplant controls at one academic medical center. METHODS: This study was a single institution retrospective review of a consecutive series of patients who underwent joint replacement following solid organ transplant as compared to a control cohort over a 10-year period. Univariable and multivariable generalized linear mixed effects models were used to compare the odds of readmission, infection, mortality, and being discharged home between transplanted (cases) and non-transplanted (control) patients. RESULTS: Transplant and non-transplant cohorts had similar BMI, although transplant patients were younger (61 versus 65 years) and had a higher incidence of Diabetes (55% vs. 16%). On multivariable analysis, there was no difference in the odds of re-admission or rate of infection, but there was an increased risk of death and admission to a rehab facility in the transplant cohort. CONCLUSION: Overall, this study demonstrates that solid organ transplant alone does not increase the risk of peri-operative complications in patients who underwent hip and knee replacement. However, it should be expected that these patients have a higher mortality rate and that many of them will need to be discharged to a post-acute care facility.

Surgical Trends in the Treatment of Supracondylar Humerus Fractures in Early Career Practice: An American Board of Orthopaedic Surgery (ABOS) Part-II Database Study.

BACKGROUND: Pediatric supracondylar humerus fractures are the most common elbow injury in children, accounting for 12% to 17% of all childhood fractures. A lack of information exists regarding complication rates on the basis of fellowship status and geography. METHODS: The American Board of Orthopaedic Surgery (ABOS) Part-II database was used to identify candidates who performed either percutaneous or open treatment of humeral supracondylar or transcondylar fractures between 2002 and 2016 on patients aged 0 to 12 years. Candidates were categorized by fellowship training experience. Information analyzed included fellowship status, surgical procedure, complications, and geographic location of treatment. Data were analyzed utilizing the χ and Fischer exact tests and were considered significant if P≤0.05. RESULTS: A total of 9169 cases (mean, 5.36+2.27 y; range, 0 to 12) were identified between 2002 and 2016, 8615 of which were treated with closed reduction and percutaneous pinning, whereas 554 were treated with an open procedure. The 5 most common fellowships treating these fractures were listed as pediatrics (4106), sports medicine (1004), none (912), trauma (732), and hand/upper extremity (543). Pediatrics performed the highest number of open reduction and internal fixation (ORIF), however, reported the statistically lowest percentage of ORIF. A statistically significant difference was identified between surgical complication rates and fellowship specialties, with pediatrics having the lowest complication rate (7.0%), followed by no fellowship (8.2%), trauma (9.0%), sports medicine (9.8%), and hand/upper extremity (11.2%) (P<0.001). This significant difference was also present when analyzing closed reduction and percutaneous pinning alone (P=0.002), however, not with the analysis of ORIF. CONCLUSIONS: Early career pediatric fellowship-trained orthopaedic surgeons are more likely to treat pediatric supracondylar humerus fractures. Overall, although they treat more patients with ORIF than any other group, their percentage treated with ORIF is statistically the lowest. A significant difference in reported complication rates was found to be associated with specific fellowship training, with pediatric fellowship-trained surgeons having the fewest complications and foot/ankle fellowship-trained surgeons associated with the highest rate of reported surgical complications. LEVEL OF EVIDENCE: Level III-retrospective cohort study.

A precise method for determining acetabular component anteversion after total hip arthroplasty.

AIMS: Several radiological methods of measuring anteversion of the acetabular component after total hip arthroplasty (THA) have been described. These are limited by low reproducibility, are less accurate than CT 3D reconstruction, and are cumbersome to use. These methods also partly rely on the identification of obscured radiological borders of the component. We propose two novel methods, the Area and Orthogonal methods, which have been designed to maximize use of readily identifiable points while maintaining the same trigonometric principles. PATIENTS AND METHODS: A retrospective study of plain radiographs was conducted on 160 hips of 141 patients who had undergone primary THA. We compared the reliability and accuracy of the Area and Orthogonal methods with two of the current leading methods: those of Widmer and Lewinnek, respectively. RESULTS: The 160 anteroposterior pelvis films revealed that the proposed Area method was statistically different from those described by Widmer and Lewinnek (p < 0.001 and p = 0.004, respectively). They gave the highest inter- and intraobserver reliability (0.992 and 0.998, respectively), and took less time (27.50 seconds (sd 3.19); p < 0.001) to complete. In addition, 21 available CT 3D reconstructions revealed the Area method achieved the highest Pearson's correlation coefficient (r = 0.956; p < 0.001) and least statistical difference (p = 0.704) from CT with a mean within 1° of CT-3D reconstruction between ranges of 1° to 30° of measured radiological anteversion. CONCLUSION: Our results support the proposed Area method to be the most reliable, accurate, and speedy. They did not support any statistical superiority of the proposed Orthogonal method to that of the Widmer or Lewinnek method. Cite this article: Bone Joint J 2019;101-B:1042-1049.

Disease course in mdx:utrophin+/- mice: comparison of three mouse models of Duchenne muscular dystrophy.

The mdx mouse model of Duchenne muscular dystrophy (DMD) is used to study disease mechanisms and potential treatments, but its pathology is less severe than DMD patients. Other mouse models were developed to more closely mimic the human disease based on knowledge that upregulation of utrophin has a protective effect in mdx muscle. An mdx:utrophin(-/-) (dko) mouse was created, which had a severe disease phenotype and a shortened life span. An mdx:utrophin(+/-) mouse was also created, which had an intermediate disease phenotype compared to the mdx and dko mice. To determine the usefulness of mdx:utrophin(+/-) mice for long-term DMD studies, limb muscle pathology and function were assessed across the life span of wild-type, mdx, mdx:utrophin(+/-), and dko mice. Muscle function assessment, specifically grip duration and rotarod performance, demonstrated that mdx:utrophin(+/-) mice were weaker for a longer time than mdx mice. Mean myofiber area was smaller in mdx:utrophin(+/-) mice compared to mdx mice at 12 months. Mdx:utrophin(+/-) mice had a higher percentage of centrally nucleated myofibers compared to mdx mice at 6 and 12 months. Collagen I and IV density was significantly higher in mdx:utrophin(+/-) muscle compared to mdx at most ages examined. Generally, mdx:utrophin(+/-) mice showed an intermediate disease phenotype over a longer time course compared to the mdx and dko mice. While they do not genetically mirror human DMD, mdx:utrophin(+/-) mice may be a more useful animal model than mdx or dko mice for investigating long-term efficacy of potential treatments when fibrosis or muscle function is the focus.

Incidence of Secondary Intra-articular Injuries With Time to Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Precise locations of chondral and meniscal damage with increased time to anterior cruciate ligament reconstruction (ACLR) have not been well described. PURPOSE/HYPOTHESIS: The purpose of the study was to determine the relationship between delay in primary ACLR and incidence of secondary intra-articular injury. The hypothesis was that patients with increased time between initial injury and ACLR will exhibit greater incidence of secondary intra-articular injury when compared with those who receive surgical intervention promptly after injury. A second hypothesis was that patients with higher preinjury activity levels or older age will exhibit greater secondary injury when compared with those with minimal preinjury activity levels and younger age. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective review was performed on 1434 patients with an anterior cruciate ligament deficiency who underwent primary ACLR at a single institution between 2009 and 2013. Patients were grouped according to time to surgery after initial injury: 0-3, 4-12, and >12 months. Operative notes were used to analyze 10 variables across time-to-surgery groups: cartilage damage in the patella, trochlea, medial femoral condyle, lateral femoral condyle, medial tibial plateau, and lateral tibial plateau; medial and lateral meniscal injury; and the incidence of procedures involving either the meniscus or cartilage. Patient age and preinjury activity level were also analyzed for the 10 variables based on time-to-surgery groups. RESULTS: An association was noted between time to surgery and increased incidence of injury in the trochlea, lateral femoral condyle, medial tibial plateau, and medial meniscus (P < .001). Different significant findings within each age group were observed, but overall positive findings were seen in the same 4 locations described above. On the basis of preinjury activity level, the less active patients were most at risk for medial meniscal and trochlear injury, while the more active patients were most at risk for medial tibial plateau injury with increased time from injury to ACLR. CONCLUSION: Increasing time from injury to ACLR was associated with increased incidence of secondary injury seen in the trochlea, lateral femoral condyle, medial tibial plateau, and medial meniscus. Separate analyses of patient age and preinjury activity level showed similar findings, thus supporting the primary analysis.

Effects of sequential injections of hepatocyte growth factor and insulin-like growth factor-I on adult rabbit extraocular muscle.

PURPOSE: To determine whether hepatocyte growth factor (HGF) and insulin-like growth factor-I (IGF-I) have synergistic effects in promoting extraocular muscle fiber growth and force generation. METHODS: A superior rectus muscle of adult rabbits was treated with either a single injection of HGF or sequential injections of HGF followed 1 week later by IGF-I. One week after HGF alone and 1 week after the IGF-I injection, the superior rectus muscles from treated and control orbits were examined for alterations in force generation as well as changes in myofiber size. RESULTS: Injection of HGF alone did not result in changes to muscle force, specific tension, or myofiber cross-sectional area; however, it did result in a significant increase in numbers of satellite cells. Sequential injection of HGF and IGF-I resulted in significantly increased force, specific tension, and myofiber cross-sectional areas as well as increased numbers of satellite cells. CONCLUSIONS: Preinjection with HGF augments the treatment effect of IGF-I. This synergistic effect is likely a result of HGF-induced activation of satellite cells and should allow a reduction in IGF-I dosing required to produce a given increase in extraocular muscle force generation.