The surgical target for optimal implant positioning in robotic-assisted total knee arthroplasty remains the subject of ongoing discussion. One of the proposed targets is to recreate the knee’s functional behaviour as per its pre-diseased state. The aim of this study was to optimize implant positioning, starting from mechanical alignment (MA), toward restoring the pre-diseased status, including ligament strain and kinematic patterns, in a patient population. We used an active appearance model-based approach to segment the preoperative CT of 21 osteoarthritic patients, which identified the osteophyte-free surfaces and estimated cartilage from the segmented bones; these geometries were used to construct patient-specific musculoskeletal models of the pre-diseased knee. Subsequently, implantations were simulated using the MA method, and a previously developed optimization technique was employed to find the optimal implant position that minimized the root mean square deviation between pre-diseased and postoperative ligament strains and kinematics.Aims
Methods
This pilot study reports the clinical outcomes
of a combination of partial subscapularis tendon transfer and small-head
hemiarthroplasty in patients with rotatator cuff arthropathy. A
total of 30 patients (30 shoulders; eight men and 22 women) with
a mean age of 74 years (55 to 84) were assessed at a mean follow-up
of 31 months (24 to 60). The inclusion criteria were painful cuff
tear arthropathy with normal deltoid function and a non-degenerative subscapularis
muscle and tendon and a preserved teres minor. Outcome was assessed using the University of California Los Angeles
score, the Japanese Orthopaedic Association score, and the Oxford
Shoulder Score. Radiographic measurements included the centre of
rotation distance and the length of the deltoid. All clinical scores were significantly improved post-operatively.
The active flexion and external rotation improved significantly
at the most recent follow-up (p <
0.035). Although the mean centre
of rotation distance changed significantly (p <
0.001), the mean
length of the deltoid did not change significantly from the pre-operative
value (p = 0.29). The change in the length of the deltoid with <
100° flexion was significantly less than that with >
100° (p <
0.001). Progressive erosion of the glenoid was seen in four patients.
No patient required revision or further surgery. A combination of partial subscapularis tendon transfer and small-head
hemiarthroplasty effectively restored function and relieved pain
in patients with rotator cuff arthropathy. Cite this article: 2015;97-B:1090–5.
