The effects of length and width of the stem on proximal humerus stress shielding in uncemented primary reverse total shoulder arthroplasty.

INTRODUCTION: To preserve humeral bone during RTSA, stems have been made shorter and cement avoided whenever possible. However, with the increased use of uncemented RTSA, a phenomenon comparable to the stress shielding of the hip has been described for the proximal humerus. The aim of this study was to investigate the influence of stem length and width on proximal humeral bone resorption after primary uncemented RTSA. MATERIALS AND METHODS: The prospective shoulder arthroplasty database of our institution was reviewed for all primary uncemented RTSAs from 2017 to 2020 in osteoarthritis and cuff tear arthropathy cases with > 2-year follow-up. We compared the clinical and the radiographic 2-year outcome of the short and standard length stems of the same prosthesis design. This allowed us to assess the effects of stem length and width with regard to stress shielding. Furthermore, we defined a cut-off value for the filling ratios to prevent stress shielding. RESULTS: Fifty patients were included in the analysis, nineteen were in the short stem group (SHORT) and thirty-one in the standard stem group (STANDARD). After 2 years, SHORT showed a relative Constant Score of 91.8% and STANDARD of 98.3% (p = 0.256). Stress shielding was found in 4 patients (21%) in SHORT and in 16 patients (52%) in STANDARD (p = 0.03); it occurred more frequently in patients with higher humeral filling ratios (p < 0.05). The calculated cut-off to prevent stress shielding was 0.7 (± 0.03) for the metaphyseal and distal filling ratio. CONCLUSION: While short and standard stems for RTSA have good results after 2 years, we found a significant negative effect of higher length and width of the stem with regard to stress shielding. Even though the clinical effects of stress shielding have to be assessed, short stems should be chosen with a filling ratio at the metaphyseal and distal position below 0.7. LEVEL OF EVIDENCE (A RETROSPECTIVE CASE-CONTROL STUDY): III.

Glenoid component placement in reverse shoulder arthroplasty assisted with augmented reality through a head-mounted display leads to low deviation between planned and postoperative parameters.

BACKGROUND: Navigated augmented reality (AR) through a head-mounted display (HMD) may lead to accurate glenoid component placement in reverse shoulder arthroplasty (RSA). The purpose of this study is to evaluate the deviation between planned, intra- and postoperative inclination, retroversion, entry point, depth, and rotation of the glenoid component placement assisted by a navigated AR through HMD during RSA. METHODS: Both shoulders of 6 fresh frozen human cadavers, free from fractures or other bony pathologies, were used. Preoperative computed tomography (CT) scans were used for the 3-dimensional (3D) planning. The glenoid component placement was assisted using a navigated AR system through an HMD in all specimens. Intraoperative inclination, retroversion, depth, and rotation were measured by the system. A postoperative CT scan was performed. The pre- and postoperative 3D CT scan reconstructions were superimposed to calculate the deviation between planned and postoperative inclination, retroversion, entry point, depth, and rotation of the glenoid component placement. Additionally, a comparison between intra- and postoperative values was calculated. Outliers were defined as >10° inclination, >10° retroversion, >3 mm entry point. RESULTS: The registration algorithm of the scapulae prior to the procedure was correctly completed for all cases. The deviations between planned and postoperative values were 1.0° ± 0.7° for inclination, 1.8° ± 1.3° for retroversion, 1.1 ± 0.4 mm for entry point, 0.7 ± 0.6 mm for depth, and 1.7° ± 1.6° for rotation. The deviation between intra- and postoperative values were 0.9° ± 0.8° for inclination, 1.2° ± 1.1° for retroversion, 0.6 ± 0.5 mm for depth, and 0.3° ± 0.2° for rotation. There were no outliers between planned and postoperative parameters. CONCLUSION: In this study, the use of a navigated AR system through an HMD for RSA led to low deviation between planned and postoperative values and between intra- and postoperative parameters.

Cemented vs. uncemented reverse total shoulder arthroplasty for the primary treatment of proximal humerus fractures in the elderly-a retrospective case-control study.

BACKGROUND: Uncemented reverse total shoulder arthroplasty (RTSA) for the primary treatment of proximal humerus fractures (PHF) in elderly patients was introduced at our institution in 2017. Recent reports have raised concerns about increased rates of early bone resorption at the proximal humerus with uncemented fracture stems. The aim of this study was to find out whether there was any difference in functional or radiographic outcomes between cemented and uncemented RTSA for PHF. METHODS: Seventeen consecutive patients who underwent uncemented RTSA (group nC) in 2017 and 2018 were age and sex matched (propensity score matching 1:2) to 34 patients with cemented RTSA implanted between 2011 and 2016 (group C) for the primary treatment of PHF. These two groups were compared in terms of clinical and radiographic outcomes at 2 years after the index surgery. RESULTS: The mean bone quality was low in both groups: in group nC the deltoid tuberosity index (DTI) was 1.43 (1.22-1.72) and in group C 1.42 (1.22-1.67). At the final 2 year follow-up, the relative CS was 98.3% (71-118) in group nC and 97.9% (36-125) in group C (p = 0.927); the absolute CS was 70.2 (49-89) in group nC and 68.0 (30-94) in group C (p = 0.509). Lucent lines at the humeral site were seen in 8 cases (47%) in group nC and in 13 cases (38%) in group C (p = 0.056). Compared to 3% in group C, all patients in group nC showed at least grade 1 and 65% showed grade 3 bone resorption at the proximal humerus (p < 0.001). CONCLUSION: Compared to cemented RTSA bone resorption at the proximal humerus was significantly more frequent in patients with uncemented RTSA for PHF. So far, this is rather a radiographic than a clinical finding, because both groups showed very satisfying functional outcomes and low revision rates at the 2 year follow-up. LEVEL OF EVIDENCE III: A retrospective case-control study.

Patient-specific instrumentation reduces deviations between planned and postosteotomy humeral retrotorsion and height in shoulder arthroplasty.

BACKGROUND: Patient-specific instrumentation (PSI) may potentially improve humeral osteotomy in shoulder arthroplasty. The purpose of this study was to compare the deviation between planned and postosteotomy humeral inclination, retrotorsion, and height in shoulder arthroplasty, using PSI vs. standard cutting guides (SCG). METHODS: Twenty fresh-frozen cadaveric specimens were allocated to undergo humeral osteotomy using either PSI or SCG, such that the 2 groups have similar age, gender, and side. Preosteotomy computed tomography (CT) scan was performed and used for the 3-dimensional (3D) planning. The osteotomy procedure was performed using a PSI designed for each specimen or an SCG depending on the group. A postosteotomy CT scan was performed. The preosteotomy and postosteotomy 3D CT scan reconstructions were superimposed to calculate the deviation between planned and postosteotomy inclination, retrotorsion, and height. Outliers were defined as cases with 1 or more of the following deviations: >5° inclination, >10° retrotorsion, and >3 mm height. The deviation and outliers in inclination, retrotorsion, and height were compared between the 2 groups. RESULTS: The deviations between planned and postosteotomy parameters were similar among the PSI and SCG groups for inclination (P = .260), whereas they were significantly greater in the SCG group for retrotorsion (P < .001) and height (P = .003). There were 8 outliers in the SCG group, compared with only 1 outlier in the PSI group (P = .005). Most outliers in the SCG group were due to deviation >10° in retrotorsion. CONCLUSION: After 3D planning, PSI had less deviation between planned and postosteotomy humeral retrotorsion and height, relative to SCG.

The Impact of Surgical Strategy and Rifampin on Treatment Outcome in Cutibacterium Periprosthetic Joint Infections.

BACKGROUND: Cutibacterium species are common pathogens in periprosthetic joint infections (PJI). These infections are often treated with ß-lactams or clindamycin as monotherapy, or in combination with rifampin. Clinical evidence supporting the value of adding rifampin for treatment of Cutibacterium PJI is lacking. METHODS: In this multicenter retrospective study, we evaluated patients with Cutibacterium PJI and a minimal follow-up of 12 months. The primary endpoint was clinical success, defined by the absence of infection relapse or new infection. We used Fisher's exact tests and Cox proportional hazards models to analyze the effect of rifampin and other factors on clinical success after PJI. RESULTS: We included 187 patients (72.2% male, median age 67 years) with a median follow-up of 36 months. The surgical intervention was a 2-stage exchange in 95 (50.8%), 1-stage exchange in 51 (27.3%), debridement and implant retention (DAIR) in 34 (18.2%), and explantation without reimplantation in 7 (3.7%) patients. Rifampin was included in the antibiotic regimen in 81 (43.3%) cases. Infection relapse occurred in 28 (15.0%), and new infection in 13 (7.0%) cases. In the time-to-event analysis, DAIR (adjusted hazard ratio [HR] = 2.15, P = .03) and antibiotic treatment over 6 weeks (adjusted HR = 0.29, P = .0002) significantly influenced treatment failure. We observed a tentative evidence for a beneficial effect of adding rifampin to the antibiotic treatment-though not statistically significant for treatment failure (adjusted HR = 0.5, P = .07) and not for relapses (adjusted HR = 0.5, P = .10). CONCLUSIONS: We conclude that a rifampin combination is not markedly superior in Cutibacterium PJI, but a dedicated prospective multicenter study is needed.

Outcomes of intra-articular calcaneal fractures: surgical treatment of 114 consecutive cases at a maximum care trauma center.

BACKGROUND: The aim of this retrospective monocentric study was to investigate the outcomes of surgically treated intra-articular calcaneus fractures in a maximum care trauma center. METHODS: One hundred forty patients who had undergone surgery for intra-articular calcaneal fractures between 2002 and 2013 were included. One hundred fourteen cases with 129 fractures were eligible to participate in the study of which 80 were available for a clinical and radiological follow-up. 34 patients were followed up by telephone interview only. Outcome measures included the American Orthopaedic Foot and Ankle Society (AOFAS) hindfoot score, Short Form 36 Health Status Survey (SF-36), complications, and subsequent surgeries. RESULTS: Mean follow-up was 91 months (range 12-183). The overall complication rate was 29% (37/129 ft). Disturbed wound healing (11%) and infection (5%) occurred most commonly. Non-union (4%) only occurred in smokers (p = 0.02). A high rate of posttraumatic subtalar arthritis (77%) and need for subsequent subtalar fusion (18%) without independent risk factors for subsequent subtalar fusion was found. The revision rate was high (60%) after primary fusion. Mean AOFAS-hindfoot score was 74 (Sanders I: 99, Sanders II: 74, Sanders III: 77, Sanders IV: 70). The postoperative Boehler angle improved significantly in all subgroups (p < 0.01). Patients with a decreased Boehler angle between postoperative images and the follow-up had significantly lower AOFAS hindfoot scores (p < 0.01). CONCLUSIONS: Our data can aid decision-making in the treatment of calcaneal fractures. We advocate to use primary subtalar fusion with caution due to the high revision rate. Smoking status should always be considered. LEVEL OF EVIDENCE: Level III, retrospective cohort study.

How Do Scapulothoracic Kinematics During Shoulder Elevation Differ Between Adults With and Without Rotator Cuff Arthropathy?

BACKGROUND: Rotator cuff arthropathy with loss of active arm elevation can be successfully treated with nonanatomic reverse total shoulder arthroplasty to restore active elevation. Shoulder kinematics in this context predominantly focus on glenohumeral motion, neglecting scapular motion, although both substantially contribute to global shoulder motion. Because scapular kinematics are difficult to assess clinically and in the laboratory, they are not well understood and therefore are often reduced to glenohumeral models with a static scapula. QUESTIONS/PURPOSES: (1) Does the scapulohumeral rhythm (scapular rotation/glenohumeral elevation ratio) change during arm elevation? (2) Is there any scapular motion before arm elevation becomes clinically visible? (3) How do scapulothoracic kinematics during shoulder elevation differ between adults with and without rotator cuff arthropathy? METHODS: This was a comparative kinematics study of 20 young adult volunteers (reference group) without rotator cuff impairment (seven females, 13 males; mean age: 27 ± 3.5 years) and 20 patients (22 shoulders) with cuff tear arthropathy (10 females, 10 males; mean age: 74 ± 6.2 years). We used a three-dimensional (3-D) motion analysis system from Vicom with eight high-speed infrared cameras (frame rate 200 Hz) and 25 skin markers. Kinematics were studied for scapulothoracic and glenohumeral movements using the Upper Limb Evaluation in Movement Analysis (ULEMA) open-source model. The main motion studied was active arm elevation in the scapular plane. After data cleaning, modeling, and normalization, changes of scapulohumeral rhythm and scapular motion at the beginning of arm elevation were analyzed qualitatively, and statistical parametric mapping was applied to study the difference in scapulothoracic kinematics between adults with and without rotator cuff arthropathy. RESULTS: The scapular rhythm changes continuously during elevation. Whereas in people without rotator cuff arthropathy, a homogenous proportional relative angular contribution between 85° and 120° could be observed, this regular pattern was disturbed in patients with rotator cuff arthropathy. We observed medial scapular rotation before arm elevation became visible, followed by low lateral or even medial scapular rotation (approximately up to 25°) at the beginning of arm elevation. Patients with rotator cuff arthropathy exhibited more scapulothoracic motion between 50° and 93° of elevation than the reference group. CONCLUSIONS: Our study introduces a double-normalized data analysis that allows for a more detailed assessment of complex scapular kinematics in a noninvasive way. Scapulothoracic motion is more complex than previously reported, especially in patients with rotator cuff arthropathy. The scapulohumeral rhythm changes dynamically throughout arm elevation. There is counter-directed scapular rotation because of muscular engagement before clinically visible arm elevation. Compared with the homogenous shoulder kinematics in the reference group, patients with rotator cuff arthropathy show a different pattern with predominantly scapular motion in the range between 50° and 93° of arm elevation. CLINICAL RELEVANCE: The findings of this study suggest that there is a specific pattern of scapular motion during arm elevation in patients with rotator cuff arthropathy. Our study introduces a new noninvasive method that allows for simultaneous analysis of glenohumeral and scapular kinematics. This will enable to investigators explore whether active arm elevation and the physiological motion pattern can be restored after, for example, reverse total shoulder arthroplasty despite a nonanatomic prosthesis configuration.

Septic arthritis due to streptococci and enterococci in native joints: a 13 year retrospective study.

OBJECTIVES: Streptococcal species are the second most common cause of native joint septic arthritis (SA). However, there are few systematic data about streptococcal SA. METHODS: The medical records of adults with SA caused by streptococci, pneumococci, and enterococci at our tertiary care centre between 2003 and 2015 were reviewed. RESULTS: 71 patients (34% female) with 83 affected joints were included. Median age was 62 years. A single joint was involved in 62 patients (87%). One or more comorbidities were present in 58 patients (82%). 16 patients (23%) had a concomitant soft-tissue infection overlying the affected joint. The hematogenous route was the dominating pathogenesis (42/71, 59%). 9 (13%) patients were diagnosed with endocarditis. The knee was the most commonly affected joint (27/83, 33%) followed by shoulder (13/83, 16%). ß-haemolytic streptococci were most commonly identified (37/71, 52%) followed by polymicrobial infections (12/71, 17%). Surgical interventions included arthroscopic irrigation and debridement in 31 (44%), arthrotomy in 23 (32%), and amputation in five patients (7%). Median duration of antimicrobial therapy was 42 days. Antibiotic treatment without any surgical intervention was performed in 5 (7%) patients. Outcome was good in 55 (89%) patients; mortality was 13% with four of nine deaths attributed to joint infection. Age and pathogen group independently predicted poor outcome in recursive partitioning analysis. CONCLUSIONS: Streptococcal SA was mostly due to ß-haemolytic streptococci in older and polymorbid patients. Old age, anginosus group streptococci, enterococci, and polymicrobial infections predicted poor outcome, while antibiotic treatment duration can likely be shortened.

Early Arthroscopic Repair of Acute Traumatic Massive Rotator Cuff Tears Leads to Reliable Reversal of Pseudoparesis: Clinical and Radiographic Outcome.

PURPOSE: It was the aim of this study to analyze the clinical and radiographic outcome after early arthroscopic repair regardless of the age of patients. METHODS: Patients with massive traumatic cuff tear and clinical pseudoparesis for forward elevation treated by subsequent early arthroscopic repair from 2011 until 2014 were included in this retrospective study. Exclusion criteria were Goutallier grade ≥3 fatty infiltration and prior shoulder problems or surgery. Magnetic resonance imaging (MRI), radiographs, and functional assessments were performed preoperatively and at follow-up. RESULTS: A total of 21 patients (male/female 15/6; age range: 30-83) were included. Preoperative MRI showed complete 2 tendon tears in 7 patients, 3 tendon tears in 13 patients and all tendons ruptured in one patient. All patients had full passive range of motion and the mean active elevation was 35.7° (range: 0°-60°). Nine patients also had a pseudoparesis for external rotation (mean: 10°, range: -30° to 40°). The mean delay until surgery was 33 days (range: 13-60). At follow-up (mean: 39 months, range: 24-60) all patients showed reversal of pseudoparesis, mean elevation of 165.2° (range: 110°-180°) and mean external rotation of 49.3° (range: -20° to 80°). The mean Constant score was 82 points (range: 56-95), and the mean subjective shoulder value was 93% (range: 50-100). The overall retear rate was 20% (n = 4). Fatty infiltration increased at least 1 grade in patients who had a retear and in 56% of patients (n = 9) without retear. Age was not a predictor for retear. CONCLUSIONS: This study shows that early arthroscopic repair of traumatic massive RCT with pseudoparesis may lead to successful results regardless of patients' age. A complete restoration of the function can be expected even in patients with retear. The retear rate is low and the increase of fatty infiltration minimal. LEVEL OF EVIDENCE: Level IV, case series.

Arthroscopic repair of isolated subscapularis tears: clinical outcome and structural integrity with a minimum follow-up of 4.6 years.

BACKGROUND: After isolated subscapularis repair, improvement in shoulder function has been reported at short-term review. The purpose of this study was to determine whether arthroscopic subscapularis repair provides durable improvement in objective and subjective shoulder function with a low structural retear rate. METHODS: All patients treated with arthroscopic repair of an isolated subscapularis tear between August 2003 and December 2012 with a minimum follow-up period of 4.6 years were identified from our database. A number of patients in our study cohort underwent a prior complete midterm assessment, which allowed a subgroup analysis to detect changes in structural integrity and corresponding function. Clinical and radiographic outcomes, including outcomes on conventional radiography and magnetic resonance imaging or ultrasound, were assessed. RESULTS: The study enrolled 36 shoulders with a mean patient age of 57.7 years (range, 31-75 years; standard deviation, 10.6 years). The mean follow-up period was 8.6 years (range, 4.6-13.9 years; standard deviation, 2.44 years). Internal rotation to the thoracic vertebrae was achieved in 94% of cases and was significantly improved (P < .001) compared with the preoperative situation. The mean relative Constant score improved from 68% preoperatively to 93% at final follow-up (P < .001). Magnetic resonance imaging evaluation showed a rerupture rate of 2.7% (1 of 36 shoulders). Twenty patients underwent previous complete midterm assessment (mean, 2.9 years; range, 1-4.5 years), with comparisons between midterm and long-term follow-up showing comparable results without statistically significant deterioration. CONCLUSIONS: Functional and subjective improvements in shoulder function are maintained at a mean follow-up of more than 8 years after isolated subscapularis repair and are associated with a low structural failure rate of the repair.

Evidence-based algorithm to treat patients with proximal humerus fractures-a prospective study with early clinical and overall performance results.

BACKGROUND: On the basis of patients' demands, bone quality, and fracture type, we developed an evidence-based treatment algorithm for proximal humerus fractures (PHF) that includes all treatment modalities from open reduction and internal fixation, hemiprosthesis, to reverse total shoulder arthroplasty. This study was done to assess its feasibility and early clinical outcome. MATERIALS AND METHODS: Patients with isolated PHF in 2014 and 2015 were included in this prospective study. The quality of life (EQ-5D) and the level of autonomy before injury were recorded. The fractures were classified and local bone quality was measured. When possible, patients were treated according to the algorithm. Radiographic and clinical follow-up-Constant score, subjective shoulder value, and EQ-5D-took place after 3 months and 1 year. The rate of unplanned surgery was analyzed. RESULTS: A total of 192 patients (mean age 66 years; 58 male, 134 female) were included. Of these, 160 (83%) were treated according to the algorithm. In total, 132 patients were treated conservatively, 36 with open reduction and internal fixation and 24 with reverse total shoulder arthroplasty or hemiarthroplasty. Generally, the mean EQ-5D before trauma and 1 year after treatment was equal to 0.88 to 0.9 points. After 1 year, the overall mean relative Constant score was 95% and mean subjective shoulder value 84%. Unplanned surgery was necessary in 21 patients. CONCLUSION: This comprehensive algorithm is designed as a noncompulsory treatment guideline for PHF, which prioritize the patient's demands and biology. The high adherence proves that it is a helpful tool for decision making. Furthermore, this algorithm leads to very satisfying overall results with low complication and revision rates.

Many Shoulder MRI Findings in Elite Professional Throwing Athletes Resolve After Retirement: A Clinical and Radiographic Study.

BACKGROUND: Anatomic findings on MRI scans of the shoulder likely affect patients differently based on their physical demands and fitness levels. The natural history of these anatomic findings once professional overhead athletes retire remains unclear. A better understanding of what happens with these findings after retirement may influence how we manage shoulder problems in athletes. PURPOSE: (1) What is the natural history of MRI-observed findings in the throwing and nonthrowing shoulders of professional European handball players after retirement from the sport? What proportion of these individuals have diagnosable findings on MRI, and do these findings disappear after retirement? (2) Do clinical findings such as Constant and Murley score and shoulder ROM change after retirement in these professional overhead athletes? METHODS: The inception cohort of this series consisted of the entire Swiss National European handball team except the goalkeepers. These 30 professional players also played in the highest Swiss handball league in 2001. None of these players previously had shoulder surgery. During their career, they had a clinical assessment and bilateral shoulder MRI as part of an earlier study. We sought to evaluate the players who had retired and did not have a history of shoulder surgery, to evaluate the natural history of MRI-observed findings made in the initial study during their professional career. Of the 30 players, 10 were excluded (four continued to play professionally, four declined participation, and two had surgery after the initial study), leaving 20 (66%) for analysis at a mean of 6 years (SD, 3 years) after retirement. To gain a better understanding of the evolution of these MRI findings in the longer-term, we also evaluated 18 additional former professional European handball players who did not have any history of shoulder surgery, had all played in the highest Swiss league and for the National Team, and had terminated their career at a mean of 15 years (SD, 3 years) ago. All the subjects in both study groups (those at 6 and 15 years after retirement) underwent a detailed interview, standardized clinical examination including ROM measurements, collection of the Constant and Murley scores and the subjective shoulder value of both shoulders, and bilateral shoulder MRI. MRI findings (consisting of abnormalities and normal variations) were reported as radiographic diagnoses, independent of the potential that these findings could be considered normal variations in people in this age group. RESULTS: At the initial MRI evaluation, the proportion of active professional European handballers with diagnosable MRI findings in the throwing shoulder was 19 of 20 (95%) and for the handballers with nonthrowing shoulders was 17 of 20 (85%), while 15 years after retirement, both shoulders of all subjects showed MRI findings. None of the rotator cuff tears progressed to full-thickness tears after retirement. In the throwing shoulders, we observed fewer individuals with ganglion cysts larger than 5 mm (initial followup: six of 20 [30%] versus 6 years after retirement: 0 of 20 (0%); odds ratio, 14.5; [95% CI, 0.7-283]; p = 0.044). The Constant and Murley score increased in the throwing shoulder from 93 points (SD, 6 points) at initial followup to 98 points (SD, 3 points) at a mean of 6 years after retirement (mean difference, 5 points; SD, 5 points; 95% CI, 2.5-7.4; p < 0.001), and to 97 points (SD, 3 points) at a mean of 15 years after retirement. However these differences are below the typically reported minimum clinically important difference for the Constant and Murley score, and so are unlikely to be clinically relevant. External rotation in 90° abduction remained increased in the throwing shoulder compared with the nonthrowing shoulder up to 15 years after retirement (initial followup: mean difference, 8°; p = 0.014; 15 years after retirement: mean difference, 4°; SD, 15; p = 0.026). Internal rotation remained decreased in the throwing compared with the nonthrowing shoulders (during the career: mean difference, 5° [SD, 10°], p = 0.036; 15 years after retirement: mean difference, 3° [SD, 4°], p = 0.021). CONCLUSIONS: Our data suggest that findings of the throwing shoulder like partial rotator cuff tears, bony cysts and ganglions do not progress after retirement, and sometimes they resolve. Because of this and because many MRI changes correlate poorly with clinical symptoms, the indication for surgical treatment of these findings should be questioned very carefully. LEVEL OF EVIDENCE: Level II, prognostic study.

Rounded data have a high potential for false comparative statistical results as shown with elbow arc of motion.

BACKGROUND AND HYPOTHESIS: Visually measured range-of-motion (ROM) data are usually rounded to the nearest 5° interval and then recorded. Rounding might significantly influence the outcome of statistical tests. METHODS: We performed numerical simulation of t test application on 2 datasets, as typically reported for the elbow flexion-extension arc of motion. The test was performed on exact data and then repeated on the same data rounded to the nearest 5° interval. The simulation input parameters were as follows: difference in means (1°-30°), standard deviation (1°-30°), and number of cases (15, 30, 60, and 120). Diverging results were counted to find the rate of failure. RESULTS: Depending on the given difference in means, the given standard deviation, and the number of cases, the failure rate of the t test after rounding reached up to 40%. DISCUSSION AND CONCLUSION: The accuracy of statistical tests performed on rounded ROM data is limited because of loss of information after rounding to the nearest 5° interval. This affects parametric and nonparametric tests, as well as paired and unpaired tests. In the future, authors should specify how ROM has been measured and recorded, explicitly addressing rounding. Furthermore, to test a zero hypothesis on rounded ROM data, authors should apply our P value (α) correction.

Osteosynthesis of type III acromial fractures with locking compression plate, lateral clavicular plate, and reconstruction plate: a biomechanical analysis of load to failure and strain distribution.

BACKGROUND: Acromial stress fractures following reverse shoulder arthroplasty have been increasingly studied because of potential functional impairment caused by this complication. The purpose of this study was to evaluate and compare different plating techniques for a type III acromial fracture (also referred to as "scapular spine fracture") in a biomechanical setting with special regard to primary stability and modes of failure. METHODS: Type III acromial fractures were simulated on 19 Sawbones scapulae and plated with either a lateral clavicular plate (LatCP), a locking compression plate (LCP), or a reconstruction plate (RecoP). We performed testing on 5 scapulae for each plate according to a staircase protocol (100 cycles each step): 50 N and 100 N, then increasing 100 N each step up to 800 N or until failure. The last series of mechanical tests included 3-dimensional micro-motion analysis. RESULTS: The average force needed to cause failure of the osteosynthesis construct was 376 N for the LatCP, 506 N for the LCP, and 360 N for the RecoP. The difference between the LCP and RecoP was significant (P = .047). The average displacements of the acromion were 12.1 mm, 13.4 mm, and 11.7 mm, respectively. The spring constant was not significantly different between the plates. The LatCP showed increased strain medially, whereas the strain on the RecoP was spread more laterally. The LCP presented a balanced strain distribution, spread evenly over the fracture line. CONCLUSIONS: In a biomechanical setting, the LCP showed superiority over the LatCP and RecoP as stabilization hardware for type III acromial fractures.

Sidus Stem-Free Shoulder System for primary osteoarthritis: short-term results of a multicenter study.

BACKGROUND: The aim of this prospective multicenter study was to evaluate clinical and radiologic results of a new metaphyseal anchored system. This system features a different anchor geometry that potentially leads to better bony integration and less loosening. METHODS: From November 2012 until December 2015, 148 patients (151 shoulders) were treated with the Sidus Stem-Free Shoulder System at 9 centers in Europe. The main indication was primary osteoarthritis (80.1%). This analysis only includes patients diagnosed with primary osteoarthritis (n = 121). A clinical evaluation was performed using the Constant-Murley score, Subjective Shoulder Value, American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form, and range of motion. Radiologic assessment was based on the occurrence of radiolucent lines and signs of implant migration, osteolysis, loosening, and heterotopic ossification. RESULTS: We evaluated 105 patients after a follow-up period of 2 years. There were 53 women and 52 men. The average age was 64 years. Total shoulder arthroplasty was performed in 73 cases and hemiarthroplasty in 32. The Constant-Murley score improved from 26 points preoperatively to 70 points at 2 years' follow-up (P < .001). The Subjective Shoulder Value increased from 34% to 84% (P < .001), and the American Shoulder and Elbow Surgeons Standardized Shoulder Assessment Form increased from 34 points to 86 points (P < .001). Radiologically, neither migration nor loosening was found. However, radiolucent lines of 2 mm or greater could be detected around the glenoid in 2 cases, but none of them have had clinical relevance yet. The overall complication rate was 6.7%, and the revision rate was 0%. CONCLUSION: Patients with the Sidus Stem-Free Shoulder System achieve good clinical and radiologic short-term results that are comparable with the results of other stem-free shoulder implants.

Evaluation of ninety-six periprosthetic hip joint infections seen within five consecutive years.

Periprosthetic hip joint infections (PHJI) are severe complications. In 2003 Zimmerli published a well-noted treatment algorithm for PHJI. The aim of this study is to evaluate outcome, analyze the applied treatment regimen and compare it to the proposed algorithm. We evaluated the outcome of 96 PHJI treated at our institution between 2008 and 2012 and analysed adherence to the algorithm and outcome in coherence with the algorithm. The operations performed were irrigation and debridement with exchange of mobile parts (45%), two-stage exchange (36%), one-stage exchange (12%) and permanent explantation (7%). 47% were acute infections, 53% were chronic. Staphylococcus aureus was the most common pathogen. The overall success rate was 88%. In 12% of the cases the chosen operation didn't follow the algorithm. Of these only 10% was successfully treated with the primary operation. We find that the algorithm proposed by Zimmerli is a useful tool and easy to translate into clinical practice. When followed it yields a high success rate.

How bone quality may influence intraoperative and early postoperative problems after angular stable open reduction-internal fixation of proximal humeral fractures.

BACKGROUND: With the introduction of the deltoid tuberosity index (DTI), a simple radiographic tool has become available to measure bone mineral density of the proximal humerus. The aim of this study was to assess the influence of local bone mineral density on the early failure rate after angular stable open reduction-internal fixation of proximal humeral fractures (PHFs). METHODS: We retrospectively followed up all patients treated with angular stable implants for PHFs from 2007 to 2014. The fractures were classified according to Neer, and the DTI, metaphyseal head extension (MHE), medial hinge displacement, and quality of reduction were assessed. Failures were defined as head screw cutouts. RESULTS: The study included 146 patients (mean age, 66 years; range, 20-94 years). The mean follow-up period was 11 months (range, 3-94 months). Of the fractures, 91% were classified as 2- or 3-part fractures and 9% as 4-part fractures. The mean DTI was 1.44 (range, 1.19-2.11), and the mean MHE was 12 mm (range, 0-48 mm). The reduction result was at least acceptable in 80% of fractures. Screw cutouts were found in 23%. The DTI and MHE were the most significant preoperative predictors for the reduction result. The DTI (P = .036) and age (P = .02) were independent preoperative factors, and a good reduction (P = .001) was the only intraoperative factor influencing cutout. DISCUSSION: This study proves that good bone quality and a long MHE are helpful for the reduction. Furthermore, good bone quality, a younger age, and a good reduction prevent later cutout. We conclude that local bone quality is a relevant factor in the treatment plan for PHFs.

Lateral subvastus approach with tibial tubercle osteotomy for primary total knee arthroplasty: clinical outcome and complications compared to medial parapatellar approach.

PURPOSE: The lateral subvastus approach (LSVA) with tibial tubercle osteotomy (TTO) is an alternative approach for total knee arthroplasty (TKA) in selected patients. The aim of this study was to compare clinical outcomes between LSV and medial parapatellar approaches for primary TKA and to investigate incidence of complications related to TTO. METHODS: A total of 580 patients with primary TKA, meeting the inclusion criteria, were treated at our hospital from February 2006 until February 2013. All patients' data were included in the local arthroplasty register and were followed up 12 months postoperatively. The data set contains: demographic data, the WOMAC score, the KSS as well as knee flexion and complications related to tibial tubercle osteotomy. RESULTS: The clinical outcome after TKA using the LSVA combined with TTO was comparable with those using the medial standard approach 1 year postoperatively. Four patients (3.8 %) needed a revision due to complications related to tubercle osteotomy. CONCLUSIONS: The LSVA is thus a viable alternative in cases of primary TKA if technical difficulties with the medial approach are anticipated. Applying precise surgical technique, the LSVA seems to be a safe and reproducible procedure.

Deltoid Tuberosity Index: A Simple Radiographic Tool to Assess Local Bone Quality in Proximal Humerus Fractures.

BACKGROUND: Osteoporosis may complicate surgical fixation and healing of proximal humerus fractures and should be assessed preoperatively. Peripheral quantitative CT (pQCT) and the Tingart measurement are helpful methods, but both have limitations in clinical use because of limited availability (pQCT) or fracture lines crossing the area of interest (Tingart measurement). The aim of our study was to introduce and validate a simple cortical index to assess the quality of bone in proximal humerus fractures using AP radiographs. QUESTIONS/PURPOSES: We asked: (1) How do the deltoid tuberosity index and Tingart measurement correlate with each other, with patient age, and local bone mineral density (BMD) of the humeral head, measured by pQCT? (2) Which threshold values for the deltoid tuberosity index and Tingart measurement optimally discriminate poor local bone quality of the proximal humerus? (3) Are the deltoid tuberosity index and Tingart measurement clinically applicable and reproducible in patients with proximal humerus fractures? METHODS: The deltoid tuberosity index was measured immediately above the upper end of the deltoid tuberosity. At this position, where the outer cortical borders become parallel, the deltoid tuberosity index equals the ratio between the outer cortical and inner endosteal diameter. In the first part of our study, we retrospectively measured the deltoid tuberosity index on 31 patients (16 women, 15 men; mean age, 65 years; range, 22-83 years) who were scheduled for elective surgery other than fracture repair. Inclusion criteria were available native pQCT scans, AP shoulder radiographs taken in internal rotation, and no previous shoulder surgery. The deltoid tuberosity index and the Tingart measurement were measured on the preoperative internal rotation AP radiograph. The second part of our study was performed by reviewing 40 radiographs of patients with proximal humerus fractures (31 women, nine men; median age, 65 years; range, 22-88 years). Interrater (two surgeons) and intrarater (two readings) reliabilities, applicability, and diagnostic accuracy were assessed. RESULTS: The correlations between radiograph measurements and local BMD (pQCT) were strong for the deltoid tuberosity index (r = 0.80; 95% CI, 0.63-0.90; p < 0.001) and moderate for the Tingart measurement (r = 0.67; 95% CI, 0.42-0.83; p < 0.001). There was moderate correlation between patient age and the deltoid tuberosity index (r = 0.65; p < 0.001), patient age and the Tingart measurement (r = 0.69; p < 0.001), and patient age and pQCT (r = 0.73; p < 0.001). The correlation between the deltoid tuberosity index and the Tingart measurement was strong (r = 0.84; p < 0.001). We determined the cutoff value for the deltoid tuberosity index to be 1.44, with the area under the curve = 0.87 (95% CI, 0.74-0.99). This provided a sensitivity of 0.88 and specificity of 0.80. For the Tingart measurement, we determined the cutoff value to be 5.3 mm, with the area under the curve = 0.83 (95% CI, 0.67-0.98), which resulted in a sensitivity of 0.81 and specificity of 0.85. The intraobserver reliability was high and not different between the Tingart measurement (intraclass correlation coefficients [ICC] = 0.75 and 0.88) and deltoid tuberosity index (ICC = 0.88 and 0.82). However, interobserver reliability was higher for the deltoid tuberosity index (ICC = 0.96; 95% CI, 0.93-0.98) than for the Tingart measurement (ICC = 0.85; 95% CI, 0.69-0.93).The clinical applicability on AP radiographs of fractures was better for the deltoid tuberosity index (p = 0.025) because it was measureable on more of the radiographs (77/80; 96%) than the Tingart measurement (69/80; 86%). CONCLUSIONS: The deltoid tuberosity index correlated strongly with local BMD measured on pQCT and our study evidence shows that it is a reliable, simple, and applicable tool to assess local bone quality in the proximal humerus. We found that deltoid tuberosity index values consistently lower than 1.4 indicated low local BMD of the proximal humerus. Furthermore, the use of the deltoid tuberosity index has important advantages over the Tingart measurement regarding clinical applicability in patients with proximal humerus fractures, when fracture lines obscure the Tingart measurement landmarks. However, further studies are needed to assess the effect of the deltoid tuberosity index measurement and osteoporosis on treatment and outcome in patients with proximal humerus fractures. LEVEL OF EVIDENCE: Level IV, diagnostic study.