ABSTRACT
Background: The purpose was to report mid-term to long-term clinical outcomes in a multicentre series of patients who received stemless total shoulder arthroplasty (TSA). The hypothesis was that stemless TSA would be a safe and effective treatment with satisfactory clinical outcomes. Methods: Authors retrospectively reviewed records of 62 stemless TSAs implanted between March 2013 and December 2014. Six were excluded because they had fractures or muscular impairment, which left 56: primary osteoarthritis (n = 49), rheumatoid arthritis (n = 4), avascular necrosis (n = 1), or glenoid dysplasia (n = 2). Outcomes were absolute Constant Score (CS), age-/sex-adjusted CS, and the American Shoulder and Elbow Surgeons (ASES) score. Proportions of patients that achieved substantial clinical benefits for absolute CS and ASES scores were determined. Results: Of the 56 patients, 8 (14%) died (unrelated to TSA), 5 (9%) were lost to follow-up, and 2 (4%) refused participation. One patient was reoperated for infection with implant removal (excluded from analysis), and one for periprosthetic fracture without implant removal. At 7.6 ± 0.5 years (range 6.8-9.3), the remaining 40 patients, aged 71.0 ± 8.5 years, achieved net improvements of 40.7 ± 15.8 (CS), 62%±23% (age-/sex-adjusted CS), and 59.7 ± 16.4 (ASES). Of patients with complete absolute CS (n = 37) and ASES score (n = 28), respectively, 33 (89%) and 27 (96%) achieved substantial clinical benefits. Conclusions: Stemless TSA yields improvements in functional outcomes at mid-term to long-term that exceed the substantial clinical benefits of the absolute CS and ASES score at a mean follow-up of 7.6 years. Although the findings of this study revealed low complications and revision rates, more studies are needed to confirm long-term benefits of stemless TSA. Level of evidence: IV, case series.
ABSTRACT
Total knee arthroplasty does not restore the full range of motion of the knee. Retrospective clinical studies on knee kinematics suffer from multiple biases because the various parameters involved, that is, the posterior condylar offset, the tibial slope, and the condylar roll-back, are not individualized. The present study, based on the geometry of knee flexion, shows that a 3-mm decrease of the posterior condylar offset could reduce knee flexion by 10 degrees before the occurrence of tibiofemoral impingement. In addition, the simultaneous decrease of the tibial slope by 5 degrees could reduce the flexion by a further 5 degrees. These effects could be reinforced if the paradoxical condylar roll-forward was made to exceed 10 mm. Finally, decreasing the condylar offset in a prosthesis with a paradoxical roll-forward and a neutral tibial slope could reduce maximum obtainable knee flexion before impingement by as much as 30 degrees.
