Rotator cuff tears are the most common cause of shoulder disability, affecting 10% of the population under 60 and 40% of those aged 70 and above. Massive irreparable rotator cuff tears account for 30% of all tears and their management continues to be an orthopaedic challenge. Traditional surgical techniques, that is, tendon transfers are performed to restore shoulder motion, however, they result in varying outcomes of stability and complications. Superior capsular reconstruction (SCR) is a novel technique that has shown promise in restoring shoulder function, albeit in limited studies. To date, there has been no biomechanical comparison between these techniques. This study aims to compare three surgical techniques (SCR, latissimus dorsi tendon transfer and lower trapezius tendon transfer) for irreparable rotator cuff tears with respect to intact cuff control using a clinically relevant biomechanical outcome of rotational motion.

Eight fresh-frozen shoulder specimens with intact rotator cuffs were tested. After dissection of subcutaneous tissue and muscles, each specimen was mounted on a custom shoulder testing apparatus and physiologic loads were applied using a pulley setup. Under 2.2 Nm torque loading maximum internal and external rotation was measured at 0 and 60 degrees of glenohumeral abduction. Repeat testing was conducted after the creation of the cuff tear and subsequent to the three repair techniques. Repeated measures analysis with paired t-test comparisons using Sidak correction was performed to compare the rotational range of motion following each repair technique with respect to each specimen's intact control. P-values of 0.05 were considered significant.

At 0° abduction, internal rotation increased after the tear (intact: 39.6 ± 13.6° vs. tear: 80.5 ± 47.7°, p=0.019). Internal rotation was higher following SCR (52.7 ± 12.9°, intact - SCR 95% CI: −25.28°,-0.95°, p=0.034), trapezius transfer (74.2 ± 25.3°, intact – trapezius transfer: 95% CI: −71.1°, 1.81°, p=0.064), and latissimus transfer (83.5 ± 52.1°, intact – latissimus transfer: 95% CI: −118.3°, 30.5°, p=0.400) than in intact controls. However, internal rotation post SCR yielded the narrowest estimate range close to intact controls. At 60° abduction, internal rotation increased after the tear (intact: 38.7 ± 14.4° vs. tear: 49.5 ± 13°, p=0.005). Internal rotation post SCR did not differ significantly from intact controls (SCR: 49.3 ± 10.1°, intact – SCR: 95% CI: −28°, 6.91°, p=0.38). Trapezius transfer showed a trend toward significantly higher internal rotation (65.7 ± 21.1°, intact – trapezius transfer: 95% CI: −55.7°, 1.7°, p=0.067), while latissimus transfer yielded widely variable rotation angle (65.7 ± 38°, intact – latissimus transfer: 95% CI: −85.9°, 31.9°, p=0.68). There were no significant differences in external rotation for any technique at 0° or 60° abduction.

Preliminary evaluation in this cadaveric biomechanical study provides positive evidence in support of use of SCR as a less morbid surgical option than tendon transfers. The cadaveric nature of this study limits the understanding of the motion to post-operative timepoint and the results herein are relevant for otherwise normal shoulders only. Further clinical evaluation is warranted to understand the long-term outcomes related to shoulder function and stability post SCR.

Gentamicin sulphate is a potent antibiotic, widely used by clinicians to treat Staphylococcus aureus bacterial complications in orthopaedic surgery and osteomyelitis. Antibiotics as administered are poorly localised and can accumulate with toxic effects. Achieving a better targeted release and controlled dosage has been an ongoing unmet microengineering challenge.

In this study we evaluated the antibiotic release potential of beta tricalcium phosphate (β-TCP) micro and macrospheres to eradicate Staphylococcus aureus and maintain osteoblast biocompatibility. Gentamicin was absorbed onto and within the spheres at an average amount of 4.2 mg per sample. Human osteoblast cell studies at five days incubation showed attachment and growth on the spheres surface with no detrimental effect on the cell viability. A time delayed antibacterial efficacy test was designed with the bacteria introduced at predetermined time intervals from 0–60 minutes.

We demonstrated that hydroxyapatite covered Foraminifera nano-, micro- macrospheres facilitated the slow release of the encapsulated pharmaceutical agent. Principally, this arises owing to their unique architecture of pores, struts and channels, which amplifies physiological degradation and calcium phosphate dissolution to release attached pharmaceuticals in a controlled manner. The Staphylococcus aureus growth response following exposure to the gentamicin incorporated microspheres at various time intervals showed the complete elimination of the bacteria within 30 minutes. Gentamicin release continued with no re-emergence of bacteria.

β-TCP nano to macro size spheres show promise as potential bone void filler particles with, in this case, supplementary delivery of antibiotic agent. Owing to their unique structure, excellent drug retention and slow release properties, they could be used in reconstructive orthopaedics to treat osteomyelitis caused by Staphylococcus aureus and possibly other sensitive organisms.

Introduction

Reverse shoulder replacement is a surgical option for cuff tear arthropathy. However scapular notching is a concern. Newer designs of glenospheres are available to reduce scapular notching. Eccentric glenosphere with a lowered centre of rotation have been shown to improve range of adduction in vitro. We hypothesize that the eccentric glenosphere improve clinical outcomes and reduce scapular notching.

This biomechanical study aims to assess the different designs of glenospheres in SMR reverse total shoulder replacement in the degree of micromotion following dynamic cyclic loading, and its implication for risk of glenoid component loosening. The eccentric designs of glenospheres allowed greater range of motion from improvement in adduction. The eccentric placement of central fixation peg on the glenosphere has raised concerns of increasing micromotion of the baseplate-bone interface during cyclic loading.

In our method, the four different designs of glenospheres were tested; 36mm concentric (Standard), 36mm eccentric, 44mm concentric and 44 eccentric glenospheres. Each glenosphere underwent a thousand cycles of shear loading at four different positions of humeral abduction. The micromotion of each glenosphere baseplate were measured and compared. The 36mm eccentric glenopshere has overall the highest degree of micromotion; its degree of movement was well below the accepted 150 micrometer as the threshold for bony ingrowth inhibition.

This case series aim to report our experience with the use of fragment specific fixation plating system and cancellous bone autograft in the elective treatment of distal radius malunions.

Fourteen patients who underwent distal radial corrective osteotomy by one surgeon were followed up retrospectively. All patients had elected for this procedure for the treatment of malunions of previous distal radial fracture. The follow up assessments include each patient’s subjective functional outcomes, the objective strength and range of motion testing, and the radiographic parameters. These subjective functional outcome data collected as measured by the Disabilities of the Arm, Shoulder, and Hand questionnaire (DASH) were compared with each patient’s pre-operative status. The motion, strength and radiographic appearances were assessed in relevance to the contralateral arm.

Reverse total shoulder replacement is a viable surgical option for Cuff Tear Arthropathy. Short term results have been promising. Longer term follow-up has demonstrated a high rate of scapular notching. This is attributed to mechanical impingement between the humeral cup and scapular neck when the arm is fully adducted. The long term sequelae of scapular notching are unclear but there is concern that it may compromise fixation of the glenoid component and affect functional outcomes.

Design modifications to address this problem include the newly available eccentric glenospheres and larger diameter glenospheres. These glenospheres are designed to offer greater ranges of motion and theoretically may reduce the risk of impingement and notching. The purpose of this biomechanical study is to demonstrate the difference in range of motions with each design of glenosphere. To our knowledge there is no published literature evaluating this design differences.

The SMR (Lima Orthotec) reverse total shoulder prothesis was implanted into a synthetic bone model (Sawbones, Pacific Laboratories, Vashon, Washington). Four different types of glenospheres (Standard 36 mm, Eccentric 36 mm, Standard 44 mm, Eccentric 44 mm) were then implanted into the same model which was fixed on a measurement table. The precision coordinate measurement device (FARO-Arm, SO6/Rev22, FARO Technologies Inc., Lake Mary, Florida) was used to establish the centres of rotation and ranges of motion.

To date, the collection of data has just been completed, but the data are yet to be analysed. In conclusion, this is a biomechanical study evaluating the ranges of motion and risk of notching, comparing different designs of glenospheres in Reverse Total Shoulder Joint Replacement.