Peri-prosthetic stress fractures after reversed shoulder arthroplasty

Introduction: Reversed shoulder prostheses have a semi-congruent design. Furthermore, the center of rotation is inferiorly displaced and a significant tension in the deltoid is often necessary to ensure the joint stability. Consequently, stress transmitted to peri-prosthetic bone may be increased, and could lead to stress fractures. We review a series of patients after reversed shoulder arthroplasty (RSA) and look specifically at the occurrence of postoperative peri-prosthetic stress fractures. Methods: Between 2001 and 2006, 46 consecutive RSA were performed. There were 26 women and 20 men with a mean age of 74 years (53-86). All had preoperative MRI or CT-scan, which did not reveal any fracture. All had a delto-pectoral approach with standard rehabilitation. Review was performed at a mean follow up of 30 months (6-60), and consisted of clinical and radiological (plain X-rays) examinations. Every time a fracture was suspected or in case of recurrent unexpected pain, CT-scan evaluations were performed. The occurrence of peri-prosthetic fractures was looked for. Results: Three patients (7%) sustained a scapular fracture (1 spinal and 2 acromial) without any trauma, between 3 and 6 months after the RSA. Furthermore, one of these patients developed 3 months later a spontaneous clavicular fracture, leading to an overall stress fracture rate of 9%. The four fractures were treated conservatively. Three malunions and one acromial non-union occurred. The range of motion in abduction and flexion decreased significantly after the fracture and stayed limited in all cases. All the three patients reported a recurrence of pain. Conclusion: Peri-prosthetic stress fractures, especially in the acromion and in the spine of the scapula are not unusual after RSA. The etiology is not well known. The increase of stress in peri-prosthetic bone may be due to the semi-congruent design and to an overtension of the deltoid. The management of this complication stays difficult. The conservative treatment leads to mal- or non-union, with persistent pain and limited range of motion.

Reversed shoulder arthroplasty baseplate fixed according to the major columns principle

Purpose Cadaveric study at our institution has demonstrated that optimal basaplate fixation of a reversed shoulder arthroplasty (RSA) could be achieved with screws in three major columns. Our aim was to review our early rate of aseptic glenoid loosening in a series of baseplate fixed according to this principle. Material and Methods Between 2005 and 2008, 48 RSA (Aequalis Reversed) were implanted in 48 patients with an average age of 74.4 years (range, 56 to 86 years). There were 37 women and 11 men. Twenty-seven primary RSAs were performed for cuff tear arthropathy, 3 after failed rotator cuff surgery, 6 for failed arthroplasties, 7 for acute fractures and 5 after failed ORIF. All baseplate fixation were done using a nonlocking posterior screw in the spine, a nonlocking anterior screw in the glenoid body, a locking superior screw in the coracoid and a locking inferior screw in the pillar. All patients were reviewed with standardized radiographs. The number of screws were reported. We measured the position of the screws in relation to the scapular spine and the coracoid process in two different views. We defined screw positions as totally, partially or out of the target. Finally we reported glenoid aseptic loosening which was defined as implant subsidence. Results Four patients were lost to follow-up. Thus, 44 shoulders could be reviewed after a mean follow-up of 13 months (range, 6 to 32 months). All baseplates were fixed with 4 screws. Thirty-seven (84%) screws were either partially or totally in the spine. Thus, 7 (16%) scapular spine screws were out of the target. No coracoid screw was out the target. Two (4.5%) patients had glenoid loosening. Both had a scapular spine and a coracoid screw partially in the bone. Conclusion Early aseptic glenoid loosening occurred before the two years follow-up and is most of time related to technical problems and/or insufficient bone stock and bone quality. Our study demonstrate that baseplate fixation according to the three columns principle is a reproducible technique and a valuable way to prevent early glenoid loosening.

Significant molecular and systemic adaptations after repeated sprint training in hypoxia

While intermittent hypoxic training (IHT) has been reported to evoke cellular responses via hypoxia inducible factors (HIFs) but without substantial performance benefits in endurance athletes, we hypothesized that repeated sprint training in hypoxia could enhance repeated sprint ability (RSA) performed in normoxia via improved glycolysis and O(2) utilization. 40 trained subjects completed 8 cycling repeated sprint sessions in hypoxia (RSH, 3000 m) or normoxia (RSN, 485 m). Before (Pre-) and after (Post-) training, muscular levels of selected mRNAs were analyzed from resting muscle biopsies and RSA tested until exhaustion (10-s sprint, work-to-rest ratio 1ratio2) with muscle perfusion assessed by near-infrared spectroscopy. From Pre- to Post-, the average power output of all sprints in RSA was increased (p<0.01) to the same extent (6% vs 7%, NS) in RSH and in RSN but the number of sprints to exhaustion was increased in RSH (9.4+/-4.8 vs. 13.0+/-6.2 sprints, p<0.01) but not in RSN (9.3+/-4.2 vs. 8.9+/-3.5). mRNA concentrations of HIF-1alpha (+55%), carbonic anhydrase III (+35%) and monocarboxylate transporter-4 (+20%) were augmented (p<0.05) whereas mitochondrial transcription factor A (-40%), peroxisome proliferator-activated receptor gamma coactivator 1alpha (-23%) and monocarboxylate transporter-1 (-36%) were decreased (p<0.01) in RSH only. Besides, the changes in total hemoglobin variations (Delta[tHb]) during sprints throughout RSA test increased to a greater extent (p<0.01) in RSH. Our findings show larger improvement in repeated sprint performance in RSH than in RSN with significant molecular adaptations and larger blood perfusion variations in active muscles.

Activities of daily living with reverse prostheses: importance of scapular compensation for functional mobility of the shoulder.

HYPOTHESIS: The nonanatomical design of reverse shoulder prostheses induce medial displacement of the center of rotation, impingements and may reduce the mobility of the shoulder. The aim of this study is to test the hypothesis that during activities of daily living functional mobility of the shoulder can be restored by scapular compensation. MATERIAL AND METHODS: A numerical 3-dimensional model was developed to reproduce the movement of the scapula and humerus, during 4 activities of daily living measured experimentally. This hypothesis was tested in 4 configurations of the aequalis reverse prosthesis (standard 36-mm glenosphere, 42-mm glenosphere, lateralized 36-mm glenosphere, lateralized Bony Increased-Offset Reverse Shoulder Arthroplasty [BIO-RSA]), which were implanted in the virtual model. All impingement positions were evaluated, as the required scapular compensation to avoid impingements. RESULTS: With the 36-mm glenosphere, impingements occurred only for rest of hand to back-pocket positions. The 42-mm partly improved the mobility. The 2 lateralized glenospheres were free of impingement. When impingements occurred, the scapular compensation was less than 10°. CONCLUSION: Most reverse prostheses impingements reported in clinical and biomechanical studies can be avoided, either by scapular compensation or by a glenosphere lateralization. After reverse shoulder arthroplasty, a fraction of the mobility of the gleno-humeral is transferred to the scapulo-thoracic joint.

Repeated Double-Poling Sprint Training in Hypoxia by Competitive Cross-country Skiers.

PURPOSE: Repeated-sprint training in hypoxia (RSH) was recently shown to improve repeated-sprint ability (RSA) in cycling. This phenomenon is likely to reflect fiber type-dependent, compensatory vasodilation, and therefore, our hypothesis was that RSH is even more beneficial for activities involving upper body muscles, such as double poling during cross-country skiing. METHODS: In a double-blinded fashion, 17 competitive cross-country skiers performed six sessions of repeated sprints (each consisting of four sets of five 10-s sprints, with 20-s intervals of recovery) either in normoxia (RSN, 300 m; FiO2, 20.9%; n = 8) or normobaric hypoxia (RSH, 3000 m; FiO2, 13.8 %; n = 9). Before (pre) and after (post) training, performance was evaluated with an RSA test (10-s all-out sprints-20-s recovery, until peak power output declined by 30%) and a simulated team sprint (team sprint, 3 × 3-min all-out with 3-min rest) on a double-poling ergometer. Triceps brachii oxygenation was measured by near-infrared spectroscopy. RESULTS: From pretraining to posttraining, peak power output in the RSA was increased (P < 0.01) to the same extent (29% ± 13% vs 26% ± 18%, nonsignificant) in RSH and in RSN whereas the number of sprints performed was enhanced in RSH (10.9 ± 5.2 vs 17.1 ± 6.8, P < 0.01) but not in RSN (11.6 ± 5.3 vs 11.7 ± 4.3, nonsignificant). In addition, the amplitude in total hemoglobin variations during sprints throughout RSA rose more in RSH (P < 0.01). Similarly, the average power output during all team sprints improved by 11% ± 9% in RSH and 15% ± 7% in RSN. CONCLUSIONS: Our findings reveal greater improvement in the performance of repeated double-poling sprints, together with larger variations in the perfusion of upper body muscles in RSH compared with those in RSN.

Reversed shoulder arthroplasty baseplate fixed according to the three major columns principle

Introduction: Glenoid bone volume and bone quality can render the fixation of a reversed shoulder arthroplasty (RSA) basis plate hazardous. Cadaveric study at our institution has demonstrated that optimal baseplate fixation could be achieved with screws in three major columns. Our aim is to review our early rate of aseptic glenoid loosening in a series of baseplates fixed according to this principle. Methods: Between 2005 and 2008, 48 consecutive RSA (Reversed Aequalis) were implanted in 48 patients with an average age of 74.4 years (range, 56 to 86 years). There were 37 women and 11 men. Twenty-seven primary RSAs were performed for cuff tear arthropathy, 3 after failed rotator cuff surgery, 6 for failed arthroplasties, 7 for acute fractures and 5 after failed ORIF. All baseplate fixations were done using a nonlocking posterior screw in the scapular spine, a nonlocking anterior screw in the glenoid body, a locking superior screw in the coracoid and a locking inferior screw in the pillar. All patients were reviewed with standardized radiographs. We reported the positions of the screws in relation to the scapular spine and the coracoid process in two different views. We defined screw positions as totally, partially or out of the target. Finally, we reported aseptic glenoid loosening which was defined as implant subsidence. Results: Four patients were lost to follow-up. Thus 44 shoulders could be reviewed after a mean follow-up of 16 months (range, 9 to 32 months). Thirty-seven (84%) screws were either partially or totally in the spine. Thus, 7 (16%) scapular spine screws were out of the target. No coracoid screw was out of the target. At final follow-up control, we reported no glenoid loosening. Conclusion: Early glenoid loosening occurred before the two years follow-up and is most of time related to technical problems and/or insufficient glenoid bone stock and bone quality. Our study demonstrate that baseplate fixation of a RSA according to the three columns principle is a reproducible technique and a valuable way to prevent early glenoid loosening.

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 70years (range, 47-85years), 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 52months (24-95months). 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.

Hidden branches: developments in root system architecture.

The root system is fundamentally important for plant growth and survival because of its role in water and nutrient uptake. Therefore, plants rely on modulation of root system architecture (RSA) to respond to a changing soil environment. Although RSA is a highly plastic trait and varies both between and among species, the basic root system morphology and its plasticity are controlled by inherent genetic factors. These mediate the modification of RSA, mostly at the level of root branching, in response to a suite of biotic and abiotic factors. Recent progress in the understanding of the molecular basis of these responses suggests that they largely feed through hormone homeostasis and signaling pathways. Novel factors implicated in the regulation of RSA in response to the myriad endogenous and exogenous signals are also increasingly isolated through alternative approaches such as quantitative trait locus analysis.

High-intensity intermittent training in hypoxia: a double-blinded, placebo-controlled field study in youth football players.

High-intensity intermittent training in hypoxia: A double-blinded, placebo-controlled field study in youth football players. J Strength Cond Res 29(1): 226-237, 2015-This study examined the effects of 5 weeks (∼60 minutes per training, 2 d·wk) of run-based high-intensity repeated-sprint ability (RSA) and explosive strength/agility/sprint training in either normobaric hypoxia repeated sprints in hypoxia (RSH; inspired oxygen fraction [FIO2] = 14.3%) or repeated sprints in normoxia (RSN; FIO2 = 21.0%) on physical performance in 16 highly trained, under-18 male footballers. For both RSH (n = 8) and RSN (n = 8) groups, lower-limb explosive power, sprinting (10-40 m) times, maximal aerobic speed, repeated-sprint (10 × 30 m, 30-s rest) and repeated-agility (RA) (6 × 20 m, 30-s rest) abilities were evaluated in normoxia before and after supervised training. Lower-limb explosive power (+6.5 ± 1.9% vs. +5.0 ± 7.6% for RSH and RSN, respectively; both p < 0.001) and performance during maximal sprinting increased (from -6.6 ± 2.2% vs. -4.3 ± 2.6% at 10 m to -1.7 ± 1.7% vs. -1.3 ± 2.3% at 40 m for RSH and RSN, respectively; p values ranging from <0.05 to <0.01) to a similar extent in RSH and RSN. Both groups improved best (-3.0 ± 1.7% vs. -2.3 ± 1.8%; both p ≤ 0.05) and mean (-3.2 ± 1.7%, p < 0.01 vs. -1.9 ± 2.6%, p ≤ 0.05 for RSH and RSN, respectively) repeated-sprint times, whereas sprint decrement did not change. Significant interactions effects (p ≤ 0.05) between condition and time were found for RA ability-related parameters with very likely greater gains (p ≤ 0.05) for RSH than RSN (initial sprint: 4.4 ± 1.9% vs. 2.0 ± 1.7% and cumulated times: 4.3 ± 0.6% vs. 2.4 ± 1.7%). Maximal aerobic speed remained unchanged throughout the protocol. In youth highly trained football players, the addition of 10 repeated-sprint training sessions performed in hypoxia vs. normoxia to their regular football practice over a 5-week in-season period was more efficient at enhancing RA ability (including direction changes), whereas it had no additional effect on improvements in lower-limb explosive power, maximal sprinting, and RSA performance.

Relationships between anthropometric measures and athletic performance, with special reference to repeated-sprint ability, in the Qatar national soccer team.

The aim of this study was to determine potential relationships between anthropometric parameters and athletic performance with special consideration to repeated-sprint ability (RSA). Sixteen players of the senior male Qatar national soccer team performed a series of anthropometric and physical tests including countermovement jumps without (CMJ) and with free arms (CMJwA), straight-line 20 m sprint, RSA (6 × 35 m with 10 s recovery) and incremental field test. Significant (P < 0.05) relationships occurred between muscle-to-bone ratio and both CMJs height (r ranging from 0.56 to 0.69) as well as with all RSA-related variables (r < -0.53 for sprinting times and r = 0.54 for maximal sprinting speed) with the exception of the sprint decrement score (Sdec). The sum of six skinfolds and adipose mass index were largely correlated with Sdec (r = 0.68, P < 0.01 and r = 0.55, P < 0.05, respectively) but not with total time (TT, r = 0.44 and 0.33, P > 0.05, respectively) or any standard athletic tests. Multiple regression analyses indicated that muscular cross-sectional area for mid-thigh, adipose index, straight-line 20 m time, maximal sprinting speed and CMJwA are the strongest predictors of Sdec (r(2) = 0.89) and TT (r(2) = 0.95) during our RSA test. In the Qatar national soccer team, players' power-related qualities and RSA are associated with a high muscular profile and a low adiposity. This supports the relevance of explosive power for the soccer players and the larger importance of neuromuscular qualities determining the RSA.