Matthew Posner

Gender Differences in Anterior Cruciate Ligament Injury Vary With Activity Epidemiology of Anterior Cruciate Ligament Injuries in a Young, Athletic Population

Background Previous studies have shown that women involved in similar activities as men are at increased risk for anterior cruciate ligament injuries. Hypothesis The incidence rate of complete anterior cruciate ligament tears for men and women in our athletic, college-aged population is similar. Study Design Descriptive epidemiology study. Methods Students graduating in class years 1994 to 2003 at our institution who sustained complete anterior cruciate ligament tears were assessed for mechanism of injury and type of sport played at time of injury. We calculated the incidence proportion, an estimation of risk, by gender and class year, and the incidence proportion ratio comparing men and women by class year. We also calculated incidence rates by gender and type of sport played and incidence rate ratios comparing men and women. Results There were 353 anterior cruciate ligament injuries in the 10 classes studied. We found an overall, 4-year incidence proportion of 3.24 per 100 (95% confidence interval, 2.89-3.63) for men and 3.51 (95% confidence interval, 2.65-4.65) for women (incidence proportion ratio, 1.09 [95% confidence interval, 0.80-1.47]). The overall anterior cruciate ligament injury rate, excluding male-only sports, was significantly greater in women (incidence rate ratio, 1.51 [95% confidence interval, 1.03-2.21]). We found significantly greater injury rates among women in a gymnastics course (incidence rate ratio, 5.67 [95% confidence interval, 1.99-16.16]), indoor obstacle course test (incidence rate ratio, 3.72 [95% confidence interval, 1.25-11.10]), and basketball (incidence rate ratio, 2.42 [95% confidence interval, 1.05-5.59]). Conclusion We found little gender difference in the overall risk of an anterior cruciate ligament tear; however, there were gender differences in injury rates when specific sports and activities were compared and when male-only sports were removed from the overall rate assessment.

Epidemiology of Major League Baseball Injuries

Background Little is known about the injury rates in Major League Baseball (MLB) players, as a formal injury surveillance system does not exist. The goal of this study was to characterize the epidemiology of MLB injuries over a 7-year period. Hypothesis Injuries in MLB would be common. Study Design Descriptive epidemiologic study. Methods The authors analyzed the MLB disabled list data from 2002 through 2008. Injuries were analyzed for differences between seasons, as well as during seasons on a monthly basis. The injuries were categorized by major anatomic zones and then further stratified based on injury type. Position-specific subanalyses for pitcher and position players were performed. Results From the 2002 season through the 2008 season, an average of 438.9 players per year were placed on the disabled list, for a rate of 3.61 per 1000 athlete-exposures. There was a significant 37% increase in injuries between 2005 and 2008. The highest injury rate during the season was during the month of April (5.73/1000 exposures) and the lowest in September (0.54/1000 exposures). No differences were noted in the injury rates between the National League and the American League (incidence rate ratio [IRR] = 1.06; 95% confidence interval [CI] = 0.98, 1.15). Pitchers experienced 34% higher incidence rates for injury compared with fielders during the study period (IRR = 1.34; 95% CI = 1.25, 1.44). Among all player injuries, upper extremity injuries accounted for 51.4% while lower extremity injuries accounted for 30.6%. Injuries to the spine and core musculature accounted for 11.7% while other injuries and illnesses were 6.3% of the total disabled list entries. There was a significant association between position played and anatomic region injured (P < .001), with pitchers experiencing a significantly greater proportion of injuries to the upper extremity (67.0%; 95% CI = 63.1%, 70.9%) compared with fielders (32.1%; 95% CI = 29.1%, 35.1%). Conversely, fielders experienced a significantly greater proportion of injuries to the lower extremity (47.5%; 95% CI = 43.8%, 51.1%) compared with pitchers (16.9%; 95% CI = 14.9%, 18.8%). The mean number of days on the disabled list was 56.6. Overall, a greater proportion of disability days were experienced by pitchers (62.4%; 95% CI = 62.0%, 62.8%; P < .001) compared with fielders (37.6%; 95% CI = 37.3%, 37.9%). Conclusion Injuries in MLB resulting in disabled list designation are common. Upper extremity injuries were predominant in pitchers, while lower extremity injuries are more common in position players. These data may be used in the development of a formal MLB injury database, as well as in the development and implementation of specific preseason training and in-season conditioning for injury prevention.

Isolated Tears of the Anterior Cruciate Ligament Over 30-Year Follow-up of Patients Treated With Arthrotomy and Primary Repair

Background Over 30 years ago, Feagin and Curl reported on the diagnosis and treatment of “isolated” injuries of the anterior cruciate ligament (ACL). The purpose of this study was to evaluate the long-term results of the patients initially diagnosed with tears of the ACL, with special emphasis on those treated with primary repair. Hypothesis Long-term results are unsatisfactory for open evaluation and treatment of ACL injuries with or without primary repair. Study Design Case series; Level of evidence, 4. Methods Follow-up was available on 34 of the original 57 patients (60%) who had ACL tears on evaluation by arthrotomy. The average age at the index procedure was 20 years, and average follow-up was 32 (range, 29-36) years. Twenty-five of the 26 complete ACL tears were treated with primary repair. None of the 8 partial tears was repaired. Evaluations included the subjective and symptom ratings of the International Knee Documentation Committee (IKDC) evaluation form, Lysholm score, Knee Injury and Osteoarthritis Outcome Score (KOOS), Tegner activity scale, and SANE rating. Results For the IKDC subjective score, 18 of 34 patients rated their knees as normal or nearly normal. The Lysholm scores averaged 70.1 (range, 20-100). The average SANE rating at 5 years was 74.8 (range, 49-110), and the current SANE rating averaged 68.9 (range, 10-100). The overall KOOS rating averaged 68.6 (range, 26.4-100). The Tegner activity score was 3.7. There was little difference between patients with unrepaired partial tears and those who had primary repairs. Conclusion At more than 30-year follow-up, patients have decreased activity levels and an equal mix of acceptable and unacceptable outcomes. We were unable to identify any predictive factors that correlated with the results; however, subsequent meniscal surgery did correlate with poor results. The results at greater than 30 years reinforce the 5-year results that showed unsatisfactory results after the open evaluation and treatment of ACL injuries with or without repair.

Fused deposition modeling of patient‐specific polymethylmethacrylate implants

Purpose – The purpose of this paper is to investigate the use of medical‐grade polymethylmethacrylate (PMMA) in fused deposition modeling (FDM) to fabricate porous customized freeform structures for several applications including craniofacial reconstruction and orthopaedic spacers. It also aims to examine the effects of different fabrication conditions on porosity and mechanical properties of PMMA samples.Design/methodology/approach – The building parameters and procedures to properly and consistently extrude PMMA filament in FDM for building 3D structures were determined. Two experiments were performed that examined the effects of different fabrication conditions, including tip wipe frequency, layer orientation, and air gap (AG) (or distance between filament edges) on the mechanical properties and porosity of the fabricated structures. The samples were characterized through optical micrographs, and measurements of weight and dimensions of the samples were used to calculate porosity. The yield strength, s...

Removal of a bent intramedullary nail with a posttraumatic sagittal plane deformity.

High-energy injuries may result in a femur fracture with resultant bending of a previously placed intramedullary femoral nail. A bend of the nail in the sagittal plane presents unique challenges for nail extraction and subsequent exchange nailing. The described surgical technique illustrates a simple method to straighten the sagittal plane bend in situ and performs exchange nailing although maintaining symmetric femoral length and rotation.

Rotator Cuff Weakness Is Not a Risk Factor for First-Time Anterior Glenohumeral Instability

Background: Shoulder instability is a common problem in young athletes and can lead to pain and decreased ability to participate in high-level activities. Little is known about the modifiable risk factors for glenohumeral joint instability. Hypothesis: Isometric shoulder strength at baseline would be a modifiable risk factor associated with subsequent first-time anterior instability events. Study Design: Cohort study. Methods: Study participants were freshmen entering the United States Military Academy in June 2006. All participants completed bilateral isometric strength evaluations with a hand-held dynamometer at baseline upon entry into the study. Variables measured included internal and external rotation at 0° (IR0, ER0) and internal and external rotation at 45° of abduction (IR45, ER45). All subjects were followed for subsequent glenohumeral joint instability events until graduation in May 2010. Independent t tests were used to analyze the data. Results: Baseline strength data were available for 1316 shoulders with no prior history of instability, of which 26 went on to have an acute first-time anterior shoulder instability event while the individuals were at the academy. There were no significant differences in mean strength between shoulders that did not go on to develop instability (uninjured; n = 1290) and those that did develop anterior instability (injured; n = 26). The mean strength values in pounds of force for uninjured and injured shoulders, respectively, were as follows: IR0 (49.80 vs 49.29; P = .88), ER0 (35.58 vs 33.66; P = .27), IR45 (47.38 vs 46.93; P = .88), and ER45 (40.08 vs 38.98; P = .59). Conclusion: No association was found between isometric shoulder strength measures at baseline and subsequent first-time anterior glenohumeral joint instability within the high-risk athletic population studied in this prospective cohort.

Performance of military tasks after clavicle plating

Management of displaced midshaft clavicle fractures in the military, a largely shoulder-bearing population, is controversial. We aimed to report the military-relevant functional outcomes after plate fixation. We performed a nested cross-sectional analysis of active duty service members enrolled in an ongoing multicenter, randomized trial on clavicle plating. For this analysis, we included subjects with 26 months follow-up. Outcome measures included radiographic appearance, physical examination, a military-specific questionnaire, and validated shoulder surveys. Mean follow-up for 28 clavicle fractures was 13 months. Union rate by 12 weeks was 93% (26/28). There was one case of soft tissue irritation requiring hardware removal. At latest follow-up, 75% of patients were satisfied; 68% had mild/no pain; 79% had full range of motion; 75% could perform push-ups; and 21% have deployed. For the majority of active duty personnel, rapid healing, return to military-specific tasks, and satisfaction with outcome are possible after plate fixation of clavicle fractures. However, approximately 25% report some functional limitations at 1 year.

Tibial Interference Screw Positioning Relative to the Bone Plug in ACL Reconstruction: A Biomechanical Comparison of Cortical Versus Cancellous-Sided Placement

The biomechanical strength of a bone-patellar tendon-bone graft in the tibia may vary depending on whether the interference screw abuts the cancellous vs the cortical surface of the bone plug. In a porcine model, 10×20-mm bone-patellar tendon-bone grafts were prepared and fixed in a 10-mm diameter tibial tunnel using a 9×25-mm titanium interference screw. The screw was positioned on the cancellous surface of the graft in group A (n=13) vs the cortical side of the graft in group B (n=14). Specimens underwent precycling, cyclic loading, and load-to-failure testing. The mean ultimate failure load was 493±245 N for group A vs 304±145 N for group B (P=.008). Sixty-nine percent of specimens in group A survived 1000 cycles of load testing compared with 21% of specimens in group B. Forty-three percent of specimens in group B sustained intratendinous failure adjacent to the bone plug compared with 15% of specimens in group A. Orientation of the tibial interference screw along the cancellous vs the cortical side of the graft results in superior cyclic loading and ultimate failure load characteristics. Additionally, screw placement along the cortical side may weaken the tendon interface and lead to tendon failure under load. This study indicates that placement of the tibial interference screw along the cancellous side of the graft is biomechanically favorable. However, the clinical ramifications of these findings are not clear. [Orthopedics. 2018; 41(6):337-342.].

Prospective Evaluation of Glenoid Bone Loss After First-Time and Recurrent Anterior Glenohumeral Instability Events

Objectives: Determining the amount of glenoid bone loss in patients following anterior glenohumeral instability events is critical to guiding appropriate treatment. One of the challenges in managing shoulder instability in young athletes is the absence of clear data showing the impact of each event. The purpose of this study was to prospectively determine the amount of bone loss associated with a single instability event, in the setting of both first-time and recurrent instability. Methods: We conducted a prospective cohort study of 714 athletes followed for four years. Baseline assessment included a subjective history of shoulder instability. Bilateral shoulder MRIs were obtained in all participants with and without a history of previous shoulder instability. The cohort was prospectively followed during the study period and those who sustained an anterior glenohumeral instability event were identified. A post-injury MRI was obtained and compared to the screening MRI. Glenoid width was measured for each patient’s pre- and post-injury MRI. The projected total glenoid bone loss was calculated and compared for patients with a prior history of shoulder instability. Results: Of the 714 athletes that were prospectively followed during the four-year period, 23 shoulders in 22 subjects sustained a first-time anterior instability event (5 dislocations, 18 subluxations), and six subjects with a previous history of instability sustained a recurrent anterior instability event (1 dislocation, 5 subluxations). On average, there was statistically significant glenoid bone loss (1.84 ± 1.47 mm) following a single instability event (p<0.001), equivalent to 6.8% (95% CI: 4.46%, 9.04%, range 0.71%-17.6%) of the glenoid width. Twelve shoulders (52%) demonstrated glenoid bone loss ≥ 5%, 4 shoulders demonstrated glenoid bone loss ≥13.5% and no shoulders had ≥20% glenoid bone loss after a first-time instability event. Pre-existing glenoid bone loss in subjects with a history of instability was 10.2% (95% CI: 1.96%, 18.35%, range 0.6% - 21.0%). This bone loss increased to 22.8% (95% CI: 20.53%, 25.15%, range 21.2% to 26.0%) following an additional instability event (P=0.0117). All six shoulders with recurrent instability had >20% glenoid bone loss. Conclusion: Glenoid bone loss of 6.8% was observed after a first-time anterior instability event. In the setting of recurrent instability, the total calculated glenoid bone loss was 22.8% with a high prevalence of bony Bankart lesions (5/6). The findings of this study support early stabilization of young, active subjects following a first-time anterior glenohumeral instability event. Figure 2. Clinical demonstration of a sagital en face MRI obtained prior to any instability event (A) and following a single subluxatiion event (B) with 14% bone loss and a bony Bankart. Table 2: Glenoid Bone Loss in First-time and Recurrent Instability Cohorts Instability Type No. Shoulders Δ Glenoid Width (mm) ΔGlenoid Width (%) Total Glenoid Bone Loss* (%) P value First-time 23 1.85 ± 1.49 6.8% 6.8% < .0001 Recurrent 6 3.75± 2.37 13.6% 22.8% .0117

The West Point Knot: A Sliding-Locking Arthroscopic Knot

Despite the advent of sutureless technology, knot tying remains an important skill for any arthroscopist. When one is choosing which knot to tie, there are a variety of options, with each possessing its own inherent strengths and weaknesses. The West Point knot is a sliding-locking arthroscopic knot that is relatively easy to learn and has excellent knot security. This article details the appropriate manner in which to tie this knot.