Purpose of this study is to create an experimental model of electrophysologic evaluation of the supraspinatus muscle on rats, after traumatic rupture of its tendon.

The population of this study consisted of 10 male Sprague Dawley rats weighting 300–400g. Under general anaesthesia we proceeded with traumatic rupture of the supraspinatus tendon and exposure of the muscle. The scapula was immobilized, and the supraspinatus tendon was attached to a force transducer using a 3–0 silk thread. A dissection was performed in order to identify the suprascapular nerve, which was then stimulated with a silver electrode. Stimulations were produced by a stimulator (Digitimer Stimulator DS9A) and were controlled by a programmer (Digitimer D4030). Fiber length was adjusted until a single stimulus pulse elicited maximum force during a twitch under isometric conditions. Rectangular pulses of 0.5 ms duration were applied to elicit twitch contractions. During the recordings, muscles were rinsed with Krebs solution of approximately 37 8C (pH 7.2–7.4) and aerated with a mixture of 95% O2 and 5% CO2. The output from the transducer was amplified and recorded on a digital interface (CED).

The following parameters were measured at room temperature (20–21 8C): single twitch tension; time to peak; half relaxation time; tetanic tensions at 10, 20, 40, 80 and 100 Hz; and fatigue index, which was evaluated using a protocol of low frequency (40 Hz) tetanic contraction, during 250 ms in a cycle of 1 s, for a total time of 180 s. The fatigue index value was then calculated by the formula [fatigue index=(initial tetanic tension − end tetanic tension) ∗ 100/(initial tetanic tension)]. In the end, the transducer was calibrated with standard weights and tensions were converted to grams.

The mean single twitch was 8.2, the time to peak 0.034 msec and the half relaxation time 0.028 msec. The strength of titanic muscle contractures was 5.7 msec at 10Hz and 17.7 at 100Hz. Finally, the fatigue index was calculated at 48.4.

We believe that electrophysiologic evaluation of the supraspinatus muscle in rats will help us understanding the pathology of muscle atrophy after rotator cuff tears and possibly the functional restoration after cuff repair

The aim of this study was to explore whether adverse reactions would occur during the material’s degradation period even at a later time point after surgery and whether these phenomena were clinically significant and would influence the final outcome.

12 unstable, displaced metacarpal fractures in 10 patients (7 males, 3 females; mean age 36.4 y, range 18–75 y) were treated with the Inion^® OTPSTM Biodegradable Mini Plating System. 9 patients (10 fractures) were available for follow-up (mean 25.6 months, range 14 to 44 m). For patients without appearance of foreign body reaction the minimum follow-up time was 24 months

Patients were examined both radiologically to evaluate fracture healing, and clinically by completing the DASH-score and a visual analogue scale for pain assessment. Grip strength, finger strength and range of motion of metacarpo-phalangeal and interphalangeal joints were measured.

Fracture healing occurred uneventfully in all patients within six weeks. The most important complication was a foreign body reaction observed in 4 of our patients more than a year postoperatively. All were re-operated and had the materials removed. Histological examination confirmed the diagnosis of aseptic inflammation and foreign body reaction.

Although internal fixation of metacarpal fractures by using bioabsorbable implants is a satisfactory alternative fixation method, patients should be advised of this possible late complication and should be followed postoperatively for at least one and a half year, possibly longer.

Although, reverse shoulder arthroplasty has initially been introduced for rotator cuff arthropathy, its application has been expanded on fracture sequelae, chronic dislocations and even comminuted fractures of the humeral head in elderly patients. The purpose of this study is to present our experience and the mid-term clinical results of this type prosthesis.

Between 2006 and 2008 16 reverse shoulder arthroplasties have been carried out in our department. Fourteen patients were female and 2 male with an average age of 72.4 years (55–81). Eleven patients had true rotator cuff arthropathy, 3 malunion of 4-part fractures, one chronic anterior shoulder dislocation and finally one patient had bilateral chronic posterior shoulder dislocation. In 2 cases we used the Delta prosthesis and in a further 14 cases the Aquealis Arthroplasty.

Routine postoperative follow up was at 3,6,12 and 24 months and included plain radiographic control and clinical evaluation with the Constant Shoulder Score. All patients report significant pain relief and an average improvement of the Constant Score from 40.5 to 72.3. Two patients had anterior dislocation of the prosthesis 4 days postoperatively and we proceeded to the application of a 9 mm metal spacer and bigger polyethylene size. In one patient neuroapraxia of the axillary nerve was observed; this resolved 3 months postoperatively. Continuous clinical improvement was observed in some patients up until 18 months postoperatively.

Our clinical results are very satisfactory and reveal that reverse shoulder arhroplasty is a very good option for a broad spectrum of pathologic shoulder conditions.

Purpose of this study is to create an experimental model on rats for EMG evaluation of the supraspinatus muscle after traumatic rupture of its tendon.

The population of this study consisted of 5 male rats of 300–400g. Under general anaesthesia we proceeded with traumatic rupture of the supraspinatus tendon and exposure of the muscle. The electrode of a stimulator was placed under suprascapular nerve and the supraspinatus tendon was sutured on a transducer for digital record of the produced signal. Initially we found the resting length and the electric intensity for higher muscle contracture. The parameters that were evaluated after single contracture (single twitch) were strength, time to peak, half relaxation time. Furthermore, it was evaluated the strength of tetanic contractures at 10,20,40,80,100 Hz (Stimulation for 350msec each time).Finally it was evaluated the muscle fatigue with stimulation at 40Hz for 250msec and total duration of 3 minutes. Fatigue index was calculated according to the decrease of titanic muscle contracture (Initial value-Final Value/Initial Value x 100)

Our results are presented in mean ± sd. The single twitch was 8.2(5.1),the time to peak 0.034(0.02) msec, the half relaxation time 0.028(0.008)msec. The strength of titanic muscle contractures was 5.7msec at 10Hz and 17.7 at 100Hz. Finally the fatigue index was calculated at 48.4.

We believe that EMG evaluation of the supraspinatus muscle in rats will help us understanding the pathology of muscle atrophy after rotator cuff tears and possibly the functional restoration after cuff repair.

Aim of the study: The aim of this study was to explore whether adverse reactions would occur during the material’s degradation period even at a later time point after fracture healing had been completed, in metacarpal fractures treated with third generation bioabsorbable implants.

Materials and Methods: 12 unstable, displaced metacarpal fractures in 10 consecutive patients (7 males, 3 females; mean age 36.4 y, range 18–75 y) were treated with third generation absorbable plates and screws (Inion^® OTPSTM Biodegradable Mini Plating System), where resorption is supposed to occur within 2 to 4 years. 9 patients (10 fractures) were available for follow-up (mean 25.6 months, range 14 to 44 m) and were examined both clinically and radiologically. For patients without appearance of foreign body reaction the minimum follow-up time was 24 months.

Results: Fracture healing was uneventful in all cases. A foreign body reaction was observed more than a year postoperatively in 4 patients, who were subjected to surgical debridement and implant remnants removal. Histological examination confirmed the diagnosis of aseptic inflammation and foreign body reaction. 2 further patients reported a self subsiding transient local swelling.

Conclusion: Our results indicate that modern absorbable implants with longer degradation period have not eliminated the problem of foreign body reaction, but simply postponed it at a later time postoperatively. Patients treated with bioabsorbable implants should be advised of this possible late complication and should be followed for at least two years, possibly longer.

Aim of the study: Mason type I radial head fractures are non-displaced fractures and are treated conservatively with early mobilization and excellent results. The aspiration of the accompanying haematoma is advocated by several authors in order to achieve an analgesic effect. The aim of this study was to investigate the effect of haematoma aspiration on intraarticular pressure and on pain relief after Mason I radial head fractures.

Materials and Methods: 10 patients (6 men and 4 women, age 23–47 y), who presented in the emergency department after an elbow trauma. Following plain radiographs that showed a Mason I radial head fracture, the patients were subjected to haematoma paracentesis. Initially, the intraarticular pressure was measured by using the Stryker Intra-Compartmental Pressure Monitor System. Afterwards, aspiration of the haematoma was performed, followed by a new pressure measurement without moving the needle. Finally, a brachial-elbow-wrist back slab was placed and a questionnaire was completed, including among others pain evaluation before and after haematoma aspiration by using an analogue ten point pain scale.

Results: The intraarticular elbow pressure prior to haematoma aspiration varied from 49 mmHg to 120 mmHg (mean 76.9 mmHg), while following aspiration it ranged from 9 mmHg to 25 mmHg (mean 16.7 mmHg). The mean quantity of the aspired blood was 3.45 ml (0.5 ml to 8.5 ml). Finally, the patients reported a pain decrease from 5.5 (4 to 8) before aspiration to 2.8 (1 to 4) after haematoma aspiration. Decrease for both pressure and pain was statistically significant (p< 0.001).

Conclusion: The built of an intraarticular haematoma in the elbow joint following an undisplaced Mason I radial head fracture leads to a pronounced increase of the intraarticular pressure accompanied by intense pain for the patient. The aspiration of the haematoma results in an acute pressure decrease and an immediate patient relief.

Introduction: Recent in vivo studies of flexor tendon midsubstance healing have indicated that during the first 10 days after injury and repair there is no increase in ultimate tensile force. In contrast, there is an increase of approximately 170% in the rigidity (stiffness) of the repair site and a decrease of more than 45% in the repair-site strain at 20 N force. The basis for the increase in rigidity during the early stages of tendon healing is not known, but may be due to either biological or mechanical factors. In particular, cyclic loading of the tendon repair site during post-operative rehabilitation may have a mechanical conditioning effect that increases the stiffness of the repair site independent of repair-site healing. Our objective was to determine whether or not cyclic loading of repaired flexor tendons causes an in increase in repair-site rigidity and whether or not this increase depends on the level of applied force. We simulated 10 days of passive motion rehabilitation by applying 6000 loading cycles to repaired flexor tendons ex vivo at force levels generated during passive motion rehabilitation. We then evaluated the tensile mechanical properties. We hypothesized that cyclic loading causes an increase in repair-site rigidity and a decrease in repair-site strain.

Materials and Methods Forty-eight flexor digitorum profundus (FDP) tendons with attached distal phalanges were obtained from twelve hindlimbs of six adult mongrel dogs. Specimens were randomly assigned to one of three groups: control (no loading), low-force (5 N) cyclic loading or high force (17 N) cyclic loading. Tendons were transected in Zone II, 4 cm proximal to the insertion site. They were repaired using a four-strand modified Kessler technique with double-stranded 4-0 Supramid suture (S. Jackson) supplemented with a running peripheral suture of 6-0 Prolene (Ethicon). For cyclic loading, the distal phalanx and proximal tendon stump were placed in custom clamps attached to a materials testing machine (Instron 8500R). Tendons in the low-force and high-force groups were loaded for 6000 cycles at 2 Hz from 0.5 N to peak forces of 5 and 17 N, respectively. The force levels were chosen to match the peak tendon forces that were measured in vivo for low- and high-force passive motion rehabilitation protocols of the canine forelimb; 6000 cycles were used to simulate the number of cycles applied during a 10-day period of rehabilitation (600 cycles/day). Specimens in the control group were sham loaded for an equivalent period of time (50 minutes). After cyclic loading, specimens were allowed to recover for 1 hour and then tested to failure in tension. From plots of force versus repair-site strain we determined ultimate (maximum) force (N), repair-site rigidity (N/[mm/mm]) and repair-site strain (%) at 20 N force. One-way analysis of variance was used to determine the effect of loading on tensile properties.

Results: Specimens subjected to high-force cyclic loading had significantly increased rigidity compared to specimens in the low-force and control groups. Rigidity in the high-force group was increased by 100% compared to control. Similarly, repair-site strain at 20 N was decreased by 50% in the high-force group compared to control group. Ultimate force was increased in the high force group compared to control (p = 0.02; Table), but the magnitude of the increase was only 13%. There were no significant differences between the low-force and control groups (p > 0.05).

Discussion: Based on our findings, we conclude: 1) Repair-site rigidity is increased by 100% and repair-site strain decreased by 50% following 6000 cycles of high-force (17 N) loading. In contrast, ultimate force is changed only slightly (13%) by high-force loading. 2) Mechanical conditioning of the repair site by repetitive forces applied during rehabilitation may have a consequence that has not been noted previously, i.e. it leads to increases in rigidity and decreases in strain. This effect may explain in part the changes in tensile properties observed after only 10 days of healing in vivo. 3) The lack of effect of low-force (5 N) loading on repair-site rigidity and strain is in contrast to the previous in vivo findings in which rigidity increased in the low-force rehabilitation group. This discrepancy suggests that the observed in vivo changes can not be explained entirely by mechanical conditioning effects. 4) Therefore, both biological and mechanical factors are likely to play an important role in the rapid changes in repair-site mechanical properties that occur following flexor tendon injury and repair.