Glenoid bone strain after anatomical total shoulder arthroplasty: In vitro measurements with micro-CT and digital volume correlation.

Glenoid implant loosening remains a major source of failure and concern after anatomical total shoulder arthroplasty (aTSA). It is assumed to be associated with eccentric loading and excessive bone strain, but direct measurement of bone strain after aTSA is not available yet. Therefore, our objective was to develop an in vitro technique for measuring bone strain around a loaded glenoid implant. A custom loading device (1500 N) was designed to fit within a micro-CT scanner, to use digital volume correlation for measuring displacement and calculating strain. Errors were evaluated with three pairs of unloaded scans. The average displacement random error of three pairs of unloaded scans was 6.1 µm. Corresponding systematic and random errors of strain components were less than 806.0 µÎµ and 2039.9 µÎµ, respectively. The average strain accuracy (MAER) and precision (SDER) were 694.3 µÎµ and 440.3 µÎµ, respectively. The loaded minimum principal strain (8738.9 µÎµ) was 12.6 times higher than the MAER (694.3 µÎµ) on average, and was above the MAER for most of the glenoid bone volume (98.1%). Therefore, this technique proves to be accurate and precise enough to eventually compare glenoid implant designs, fixation techniques, or to validate numerical models of specimens under similar loading.

A randomised controlled trial of shoulder block vs. interscalene brachial plexus block for ventilatory function after shoulder arthroscopy.

The shoulder block may impair ventilatory function and diaphragmatic movement less than the interscalene brachial plexus block. We randomly allocated 30 adults who underwent shoulder arthroscopy under general anaesthesia to ultrasound-guided shoulder block or interscalene block with 20 ml bupivacaine 0.5%. The primary outcome, rate of ultrasound-measured hemidiaphragmatic excursion < 25% of baseline 30 min after blockade, was reduced from 12/15 with brachial plexus block to 2/15 with shoulder block, a difference (95%CI) of 67% (40-93%), p < 0.001. The mean (SD) numeric rating scale pain scores at rest after shoulder block were higher than after interscalene block at two postoperative hours, 1.4 (1.2) vs. 0.3 (0.7), p = 0.02, but lower at 24 postoperative hours, 1.3 (1.3) vs. 3.4 (2.3), p = 0.008. Mean (SD) pain scores on movement in the shoulder and interscalene blocks were similar, with respective values of 1.9 (1.9) vs. 0.7 (1.2), p = 0.13 at two postoperative hours and 3.7 (2.3) vs. 5.3 (2.5), p = 0.41, at 24 postoperative hours.

Reduced hemidiaphragmatic paresis with extrafascial compared with conventional intrafascial tip placement for continuous interscalene brachial plexus block: a randomized, controlled, double-blind trial.

BACKGROUND.: The incidence of hemidiaphragmatic paresis with continuous interscalene brachial plexus block (CISB) can approach 100%. We tested the hypothesis that extrafascial placement of the catheter tip reduces the rate of hemidiaphragmatic paresis compared with intrafascial tip placement for CISB while providing effective analgesia. METHODS.: Seventy patients undergoing elective major shoulder surgery under general anaesthesia were randomized to receive an ultrasound-guided CISB plexus block for analgesia with the catheter tip placed either within (intrafascial group) or immediately outside (extrafascial group) the brachial plexus sheath midway between the levels of C5 and C6. Catheters were bolus dosed with ropivacaine 0.5% 20 ml before surgery, followed by an infusion of ropivacaine 0.2% at 4 ml h -1 for the first 2 days after surgery. The primary outcome was hemidiaphragmatic paresis measured by M-mode ultrasonography on postoperative day (POD) 1. Secondary outcomes included forced vital capacity, forced expiratory volume in 1 s, and rest pain scores. RESULTS.: The incidence of hemidiaphragmatic paresis on POD 1 was significantly reduced in the extrafascial group {intrafascial, 41% [95% confidence interval (CI) 25-59%]; extrafascial, 15% (95% CI 5-32%); P =0.01}. We were unable to detect a difference between groups in any of the functional respiratory outcomes or in rest pain scores [numerical rating scale (1-10): intrafascial, 3 (95% CI 2-3); extrafascial, 3 (95% CI: 2-4); P =0.93] on POD 1. CONCLUSIONS.: Placement of the catheter tip immediately outside of the brachial plexus sheath reduced the incidence of hemidiaphragmatic paresis on POD 1 associated with ultrasound-guided CISB while providing effective analgesia after major shoulder surgery. Our results do not support the routine placement of the catheter tip within the brachial plexus sheath for CISB. CLINICAL TRIAL REGISTRATION.: NCT02433561.

A semi-automated quantitative CT method for measuring rotator cuff muscle degeneration in shoulders with primary osteoarthritis.

BACKGROUND: Rotator cuff muscle degeneration is an important parameter to consider when planning shoulder arthroplasty. HYPOTHESIS: We hypothesized that rotator cuff muscle degeneration is correlated with scapulohumeral subluxation in patients planned for anatomical total shoulder arthroplasty (TSA). MATERIALS AND METHODS: We developed a semi-automated quantitative CT method to measure rotator cuff muscle degeneration, and retrospectively analyzed 107 preoperative shoulder CT scans of patients with primary osteoarthritis. On a standardized sagittal-oblique CT slice perpendicular to the scapular axis, two observers measured the cross-sectional areas of residual rotator cuff muscle tissues, normalized by the estimated area of healthy muscles. Muscle degeneration was quantified in a semi-automated manner, and divided into atrophy and fatty infiltration. Scapulohumeral subluxation was determined in 3D as the distance between the humeral head center and the glenoid surface center, projected on the same CT slice, and normalized by the humeral head radius. We tested all potential correlations between muscle degeneration and scapulohumeral subluxation. RESULTS: Muscle degeneration, primarily due to atrophy, predominated in the supraspinatus; it varied from 0.8% to 88.8%. Scapulohumeral subluxation varied from 2.5% to 72.9%, and was mainly in a posterior and postero-superior orientation. There was a significant but weak correlation between the amount of subluxation and both supraspinatus (R=0.207, P=0.032) and infraspinatus (R=0.225, P=0.020) degeneration. Inter- and intra-observer reproducibility of muscle degeneration measurements were both excellent (ICCs range=0.955-0.987 and 0.971-0.988, respectively). CONCLUSION: This new semi-automated CT method allows to quantitatively and reproducibly measure rotator cuff muscle degeneration in shoulders with primary osteoarthritis. Muscle degeneration is weakly correlated with scapulohumeral subluxation in patients planned for anatomical TSA. LEVEL OF EVIDENCE: Level IV. TYPE OF STUDY: Diagnostic retrospective study.

Stability Enhancement Using Hyaluronic Acid Gels for Delivery of Human Fetal Progenitor Tenocytes.

Tendon afflictions are very common, and their negative impact is high both at the workplace and in leisure activities. Tendinopathies are increasing in prevalence and can lead to tendon ruptures, where healing is a long process with outcomes that are often disappointing. Human fetal progenitor tenocytes (hFPTs) have been recently tested in vitro as a potential cell source to stimulate tendon regeneration. The aim of the present study was to compare different commercial hyaluronic acid (HA) gels, which could be used to resuspend hFPTs in a formulation that would allow for good delivery of the cells. No medium or growth supplement was used in the formulation in order to make it therapeutically dispensable. These conditions are stringent for cells, but surprisingly, we found that different formulations could allow a good survival for up to 3 days when stored at 4°C (refrigerator stable). The gels must allow a good survival of the cells in parallel with a good stability of the preparation over time and sufficient viscosity to remain in place if deposited on a wounded location. Moreover, the cells must conserve their ability to attach and to proliferate. hFPTs were able to survive and to recover from all of the tested gels, but some products showed some advantages over others in terms of survival and viscosity. Finally, the Ostenil Tendon HA gel fulfilled all of the requirements and presented the best compromise between a good survival and sufficient rheological characteristics to create an interesting cell delivery system.

Extrafascial injection for interscalene brachial plexus block reduces respiratory complications compared with a conventional intrafascial injection: a randomized, controlled, double-blind trial.

BACKGROUND: Hemidiaphragmatic paresis after ultrasound-guided interscalene brachial plexus block is reported to occur in up to 100% of patients. We tested the hypothesis that an injection lateral to the brachial plexus sheath reduces the incidence of hemidiaphragmatic paresis compared with a conventional intrafascial injection, while providing similar analgesia. METHODS: Forty ASA I-III patients undergoing elective shoulder and clavicle surgery under general anaesthesia were randomized to receive an ultrasound-guided interscalene brachial plexus block for analgesia, using 20 ml bupivacaine 0.5% with epinephrine 1:200 000 injected either between C5 and C6 within the interscalene groove (conventional intrafascial injection), or 4 mm lateral to the brachial plexus sheath (extrafascial injection). The primary outcome was incidence of hemidiaphragmatic paresis (diaphragmatic excursion reduction >75%), measured by M-mode ultrasonography, before and 30 min after the procedure. Secondary outcomes were forced vital capacity, forced expiratory volume in 1 s, and peak expiratory flow. Additional outcomes included time to first opioid request and pain scores at 24 h postoperatively (numeric rating scale, 0-10). RESULTS: The incidences of hemidiaphragmatic paresis were 90% (95% CI: 68-99%) and 21% (95% CI: 6-46%) in the conventional and extrafascial injection groups, respectively (P<0.0001). Other respiratory outcomes were significantly better preserved in the extrafascial injection group. The mean time to first opioid request was similar between groups (conventional: 802 min [95% CI: 620-984 min]; extrafascial: 973 min [95% CI: 791-1155 min]; P=0.19) as were pain scores at 24 h postoperatively (conventional: 1.6 [95% CI: 0.9-2.2]; extrafascial: 1.6 [95% CI: 0.8-2.4]; P=0.97). CONCLUSIONS: Ultrasound-guided interscalene brachial plexus block with an extrafascial injection reduces the incidence of hemidiaphragmatic paresis and impact on respiratory function while providing similar analgesia, when compared with a conventional injection. CLINICAL TRIAL REGISTRATION: NCT02074397.

Human Fetal Progenitor Tenocytes for Regenerative Medicine.

Tendon injuries are very frequent and affect a wide and heterogeneous population. Unfortunately, the healing process is long with outcomes that are not often satisfactory due to fibrotic tissue appearance, which leads to scar and adhesion development. Tissue engineering and cell therapies emerge as interesting alternatives to classical treatments. In this study, we evaluated human fetal progenitor tenocytes (hFPTs) as a potential cell source for treatment of tendon afflictions, as fetal cells are known to promote healing in a scarless regenerative process. hFPTs presented a rapid and stable growth up to passage 9, allowing to create a large cell bank for off-the-shelf availability. hFPTs showed a strong tenogenic phenotype with an excellent stability, even when placed in conditions normally inducing cells to differentiate. The karyotype also indicated a good stability up to passage 12, which is far beyond that necessary for clinical application (passage 6). When placed in coculture, hFPTs had the capacity to stimulate human adult tenocytes (hATs), which are responsible for the deposition of a new extracellular matrix during tendon healing. Finally, it was possible to distribute cells in porous or gel scaffolds with an excellent survival, thus permitting a large variety of applications (from simple injections to grafts acting as filling material). All of these results are encouraging in the development of an off-the-shelf cell source capable of stimulating tendon regeneration for the treatment of tendon injuries.

Enhancing clinically-relevant shoulder function assessment using only essential movements.

Kinematic functional evaluation with body-worn sensors provides discriminative and responsive scores after shoulder surgery, but the optimal movements' combination has not yet been scientifically investigated. The aim of this study was the development of a simplified shoulder function kinematic score including only essential movements. The P Score, a seven-movement kinematic score developed on 31 healthy participants and 35 patients before surgery and at 3, 6 and 12 months after shoulder surgery, served as a reference. Principal component analysis and multiple regression were used to create simplified scoring models. The candidate models were compared to the reference score. ROC curve for shoulder pathology detection and correlations with clinical questionnaires were calculated. The B-B Score (hand to the Back and hand upwards as to change a Bulb) showed no difference to the P Score in time*score interaction (P > .05) and its relation with the reference score was highly linear (R(2) > .97). Absolute value of correlations with clinical questionnaires ranged from 0.51 to 0.77. Sensitivity was 97% and specificity 94%. The B-B and reference scores are equivalent for the measurement of group responses. The validated simplified scoring model presents practical advantages that facilitate the objective evaluation of shoulder function in clinical practice.

Complications of shoulder arthroplasty for osteoarthritis with posterior glenoid wear.

BACKGROUND: Anatomical total shoulder arthroplasty (TSA) for glenohumeral osteoarthritis (OA) and severe posterior glenoid wear may entail early postoperative complications (recurrence of posterior subluxation, glenoid loosening). To avoid these mechanical problems, reverse shoulder arthroplasty (RSA) has recently been proposed, mainly for its intrinsic stability. Our purpose was to present the results of TSA and RSA in glenohumeral OA with posterior glenoid wear of at least 20°. HYPOTHESIS: By virtue of its constrained design, RSA could prevent recurrence of posterior subluxation and limit the occurrence of mechanical complications. MATERIALS AND METHODS: A consecutive series of 23 patients (27 shoulders) were treated for glenohumeral OA with total shoulder prostheses: 19 TSAs and 8 RSAs. Mean age was 70 years (range, 47-85 years), mean retroversion angle 28° (20°-50°) and mean subluxation index 74% (57-89%). Constant Score, Subjective Shoulder Value (SSV), QuickDASH and Simple Shoulder Test (SST) were measured, and radiological examinations were performed at a mean follow-up of 52 months (24-95 months). RESULTS: TSA and RSA patients respectively displayed Constant Scores of 65 and 65, SSV of 79% and 74%, QuickDASH of 16 and 27, and SST of 88 and 78. Two patients underwent surgical revision of TSA because of glenoid loosening; 52% of TSA patients presented complete radiolucent lines and 11% recurrence of posterior subluxation. CONCLUSION: Complications are frequently observed after shoulder arthroplasty for OA with severe glenoid retroversion. RSA could be an alternative to TSA for selected patients, independently of rotator cuff status. Studies on RSA in this specific indication with longer follow-up are now needed. LEVEL OF EVIDENCE: Level IV; retrospective case series.

Measurements of three-dimensional glenoid erosion when planning the prosthetic replacement of osteoarthritic shoulders.

The three-dimensional (3D) correction of glenoid erosion is critical to the long-term success of total shoulder replacement (TSR). In order to characterise the 3D morphology of eroded glenoid surfaces, we looked for a set of morphological parameters useful for TSR planning. We defined a scapular coordinates system based on non-eroded bony landmarks. The maximum glenoid version was measured and specified in 3D by its orientation angle. Medialisation was considered relative to the spino-glenoid notch. We analysed regular CT scans of 19 normal (N) and 86 osteoarthritic (OA) scapulae. When the maximum version of OA shoulders was higher than 10°, the orientation was not only posterior, but extended in postero-superior (35%), postero-inferior (6%) and anterior sectors (4%). The medialisation of the glenoid was higher in OA than normal shoulders. The orientation angle of maximum version appeared as a critical parameter to specify the glenoid shape in 3D. It will be very useful in planning the best position for the glenoid in TSR.

Can smaller-scale comprehensive cancer centers provide outstanding care in abdominal and thoracic pediatric solid tumor surgery? Results of a 14-year retrospective single-center analysis.

PURPOSE: Quality of care and its measurement represent a considerable challenge for pediatric smaller-scale comprehensive cancer centers (pSSCC) providing surgical oncology services. It remains unclear whether center size and/or yearly case-flow numbers influence the quality of care, and therefore impact outcomes for this population of patients. PATIENTS AND METHODS: We performed a 14-year, retrospective, single-center analysis, assessing adherence to treatment protocols and surgical adverse events as quality indicators in abdominal and thoracic pediatric solid tumor surgery. RESULTS: Forty-eight patients, enrolled in a research-associated treatment protocol, underwent 51 cancer-oriented surgical procedures. All the protocols contain precise technical criteria, indications, and instructions for tumor surgery. Overall, compliance with such items was very high, with 997/1,035 items (95 %) meeting protocol requirements. There was no surgical mortality. Twenty-one patients (43 %) had one or more complications, for a total of 34 complications (66 % of procedures). Overall, 85 % of complications were grade 1 or 2 according to Clavien-Dindo classification requiring observation or minor medical treatment. Case-sample and outcome/effectiveness data were comparable to published series. Overall, our data suggest that even with the modest caseload of a pSSCC within a Swiss tertiary academic hospital, compliance with international standards can be very high, and the incidence of adverse events can be kept minimal. CONCLUSION: Open and objective data sharing, and discussion between pSSCCs, will ultimately benefit our patient populations. Our study is an initial step towards the enhancement of critical self-review and quality-of-care measurements in this setting.

Importance of the subscapularis muscle after total shoulder arthroplasty.

BACKGROUND: The rotator cuff muscles are the main stabilizer of the glenohumeral joint. After total shoulder arthroplasty using anterior approaches, a dysfunction of the subscapularis muscle has been reported. In the present paper we tested the hypothesis that a deficient subscapularis following total shoulder arthroplasty can induce joint instability. METHODS: To test this hypothesis we have developed an EMG-driven musculoskeletal model of the glenohumeral joint. The model was based on an algorithm that minimizes the difference between measured and predicted muscular activities, while satisfying the mechanical equilibrium of the glenohumeral joint. A movement of abduction in the scapular plane was simulated. We compared a normal and deficient subscapularis. Muscle forces, joint force, contact pattern and humeral head translation were evaluated. FINDINGS: To satisfy the mechanical equilibrium, a deficient subscapularis induced a decrease of the force of the infraspinatus muscle. This force decrease was balanced by an increase of the supraspinatus and middle deltoid. As a consequence, the deficient subscapularis induced an upward migration of the humeral head, an eccentric contact pattern and higher stress within the cement. INTERPRETATION: These results confirm the importance of the suscapularis for the long-term stability of total shoulder arthroplasty.

An analysis of patients' understanding of 'routine' preoperative blood tests and HIV screening. Is no news really good news?

OBJECTIVES: Many patients may believe that HIV screening is included in routine preoperative work-ups. We examined what proportion of patients undergoing preoperative blood testing believed that they had been tested for HIV. METHODS: All patients hospitalized for elective orthopaedic surgery between January and December 2007 were contacted and asked to participate in a 15-min computer-assisted telephone interview (n = 1330). The primary outcome was to determine which preoperative tests patients believed had been performed from a choice of glucose, clotting, HIV serology and cholesterol, and what percentage of patients interpreted the lack of result communication as a normal or negative test. The proportion of patients agreeable to HIV screening prior to future surgery was also determined. RESULTS: A total of 991 patients (75%) completed the questionnaire. Three hundred and seventy-five of these 991 patients (38%) believed incorrectly that they had been tested for HIV preoperatively. Younger patients were significantly more likely to believe that an HIV test had been performed (mean age 46 vs. 50 years for those who did not believe that an HIV test had been performed; P < 0.0001). Of the patients who believed that a test had been performed but received no result, 96% interpreted lack of a result as a negative HIV test. Over 80% of patients surveyed stated that they would agree to routine HIV screening prior to future surgery. A higher acceptance rate was associated with younger age (mean age 47 years for those who would agree vs. 56 years for those who would not; P < 0.0001) and male sex ( P < 0.009). CONCLUSIONS: Many patients believe that a preoperative blood test routinely screens for HIV. The incorrect assumption that a lack of result communication indicates a negative test may contribute to delays in HIV diagnoses.

[When to operate on diaphyseal humeral fractures?]. / Quand faut-il opérer une fracture diaphysaire de l'humérus?

Most humeral shaft fractures are amenable to nonoperative treatment. According to shoulder and elbow functions, humeral shaft malunions are well tolerated with deformities up to 30 degrees of varus, 20 degrees of anterior bowing and 15 degrees of internal rotation. Limitations to nonoperative treatment do exist. Open fractures with extensive soft-tissue lesions, penetrating open fractures with neurological or vascular impairment are best managed with immediate stabilization. However the appropriate treatment strategy has to be adapted for each patient. Patient expectations, fracture propensity for nonunion, ability to tolerate nonoperative treatment for medical or social reasons should be taken into consideration for operative indication.

Tightening force and torque of nonlocking screws in a reverse shoulder prosthesis.

BACKGROUND: Reversed shoulder arthroplasty is an accepted treatment for glenohumeral arthritis associated to rotator cuff deficiency. For most reversed shoulder prostheses, the baseplate of the glenoid component is uncemented and its primary stability is provided by a central peg and peripheral screws. Because of the importance of the primary stability for a good osteo-integration of the baseplate, the optimal fixation of the screws is crucial. In particular, the amplitude of the tightening force of the nonlocking screws is clearly associated to this stability. Since this force is unknown, it is currently not accounted for in experimental or numerical analyses. Thus, the primary goal of this work is to measure this tightening force experimentally. In addition, the tightening torque was also measured, to estimate an optimal surgical value. METHODS: An experimental setup with an instrumented baseplate was developed to measure simultaneously the tightening force, tightening torque and screwing angle, of the nonlocking screws of the Aquealis reversed prosthesis. In addition, the amount of bone volume around each screw was measured with a micro-CT. Measurements were performed on 6 human cadaveric scapulae. FINDINGS: A statistically correlated relationship (p<0.05, R=0.83) was obtained between the maximal tightening force and the bone volume. The relationship between the tightening torque and the bone volume was not statistically significant. INTERPRETATION: The experimental relationship presented in this paper can be used in numerical analyses to improve the baseplate fixation in the glenoid bone.