Short-term outcomes and survival of pyrocarbon hemiarthroplasty in the young arthritic shoulder.

HYPOTHESIS: The purpose was to report the short-term outcomes and survival of hemiarthroplasty with a pyrocarbon head (HA-PYC) for the treatment of shoulder osteoarthritis in patients aged ≤ 60 years. We hypothesized that HA-PYC could be an alternative to hemi-metal (avoiding the risk of rapid glenoid erosion) and total shoulder arthroplasty (TSA) (avoiding the risk of rapid glenoid loosening) in an active patient population. METHODS: Sixty-four consecutive patients (mean age, 53 years) who underwent HA-PYC for glenohumeral osteoarthritis were included. The primary outcome was revision to TSA or reverse shoulder arthroplasty. Secondary outcome measures included functional outcome scores; return to work and sports; and radiographic evaluation of humeral reconstruction quality using the "circle method" of Mears, as well as glenoid erosion severity and progression using the Sperling classification. Patients were reviewed and underwent radiography at an average follow-up of 33 months (range, 24-60 months). RESULTS: At last follow-up, the rate of survival of the HA-PYC prosthesis was 92%. Revision was performed in 5 patients, with a mean delay of 24 months (range, 15-37 months): 1 conversion to TSA and 4 conversions to reverse shoulder arthroplasty. The Constant score and Subjective Shoulder Value increased from 36 points (range, 26-50 points) to 75 points (range, 69-81 points) and from 35% (range, 20%-50%) to 80% (range, 75%-90%), respectively (P < .001). Postoperatively, 91% of the patients (42 of 46) returned to work and 88% (15 of 17) returned to sport. The severity of preoperative and postoperative glenoid wear (Sperling grade 3 or 4) had no influence on the functional results. Patients who underwent associated concentric glenoid reaming (n = 23) had similar Constant scores and Subjective Shoulder Values (P = .95) to other patients and did not show more progression of glenoid wear. Nonanatomic reconstruction of the proximal humerus (center of rotation of the prosthesis > 3 mm from the anatomic center) occurred in 29% (18 of 62 patients) and was associated with significantly lower functional and subjective results, more complications (subscapularis insufficiency and/or symptomatic glenoid erosion), and a higher risk of revision. The additional 1.5-mm thickness of the metal disc under the pyrocarbon head was found to be the main reason for oversizing of the prosthetic head. CONCLUSION: HA-PYC is a reliable procedure to treat shoulder osteoarthritis and allows return to work and sports in a young (≤60 years) and active patient population. The severity of glenoid bone erosion or the association with glenoid reaming does not affect functional outcomes and failure risk. By contrast, nonanatomic reconstruction of the proximal humerus after HA-PYC (because of humeral head oversizing) occurred in one-third of the cases and is associated with lower functional outcomes, as well as higher risks of complications and revision.

Three-Dimensional Measurement of Proximal Humerus Fractures Displacement: A Computerized Analysis.

Neer's classification for proximal humerus fractures (PHFs) uses 10 mm and 45° thresholds to distinguish displaced fragments. While this system was originally developed referencing 2D X-rays, fracture displacements occur in three dimensions. Our work aimed to develop a standardized and reliable computerized method for measuring PHF 3D spatial displacements. CT scans of 77 PHFs were analyzed. A statistical shape model (SSM) was used to generate the pre-fracture humerus. This predicted proximal humerus was then used as a "layer" to manually reduce fragments to their native positions and quantify translation and rotation in three dimensions. 3D computerized measurements could be calculated for 96% of fractures and revealed that 47% of PHFs were displaced according to Neer's criteria. Valgus and varus head rotations in the coronal plane were present in 39% and 45% of cases; these were greater than 45° in 8% of cases and were always associated with axial and sagittal rotations. When compared to 3D measurements, 2D methods underestimated the displacement of tuberosity fragments and did not accurately assess rotational displacements. The use of 3D measurements of fracture displacement is feasible with a computerized method and may help further refine PHF analysis and surgical planning.