Routman Hd

Scapular notching and osteophyte formation after reverse shoulder replacement

This study provides recommendations on the position of the implant in reverse shoulder replacement in order to minimise scapular notching and osteophyte formation. Radiographs from 151 patients who underwent primary reverse shoulder replacement with a single prosthesis were analysed at a mean follow-up of 28.3 months (24 to 44) for notching, osteophytes, the position of the glenoid baseplate, the overhang of the glenosphere, and the prosthesis scapular neck angle (PSNA). A total of 20 patients (13.2%) had a notch (16 Grade 1 and four Grade 2) and 47 (31.1%) had an osteophyte. In patients without either notching or an osteophyte the baseplate was found to be positioned lower on the glenoid, with greater overhang of the glenosphere and a lower PSNA than those with notching and an osteophyte. Female patients had a higher rate of notching than males (13.3% vs 13.0%) but a lower rate of osteophyte formation (22.9% vs 50.0%), even though the baseplate was positioned significantly lower on the glenoid in females (p = 0.009) and each had a similar mean overhang of the glenosphere. Based on these findings we make recommendations on the placement of the implant in both male and female patients to avoid notching and osteophyte formation.

Effect of reverse shoulder design philosophy on muscle moment arms

This study analyzes the muscle moment arms of three different reverse shoulder design philosophies using a previously published method. Digital bone models of the shoulder were imported into a 3D modeling software and markers placed for the origin and insertion of relevant muscles. The anatomic model was used as a baseline for moment arm calculations. Subsequently, three different reverse shoulder designs were virtually implanted and moment arms were analyzed in abduction and external rotation. The results indicate that the lateral offset between the joint center and the axis of the humerus specific to one reverse shoulder design increased the external rotation moment arms of the posterior deltoid relative to the other reverse shoulder designs. The other muscles analyzed demonstrated differences in the moment arms, but none of the differences reached statistical significance. This study demonstrated how the combination of variables making up different reverse shoulder designs can affect the moment arms of the muscles in different and statistically significant ways. The role of humeral offset in reverse shoulder design has not been previously reported and could have an impact on external rotation and stability achieved post‐operatively.

Local injection of liposomal bupivacaine combined with intravenous dexamethasone reduces postoperative pain and hospital stay after shoulder arthroplasty

BACKGROUND Alternative techniques have been developed to address pain after shoulder arthroplasty and are well documented. We evaluated the effect of adding intraoperative liposomal bupivacaine and intravenous dexamethasone during shoulder arthroplasty. METHODS We retrospectively reviewed 2 consecutive cohorts undergoing elective shoulder arthroplasty. The 24 patients in cohort 1 and the 31 patients in cohort 2 received perioperative multimodal management with preoperative and postoperative intravenous and oral narcotics, gabapentin, nonsteroidal anti-inflammatory drugs, acetaminophen, and single-injection interscalene block. Cohort 2 also received 8 to 10 mg of intravenous dexamethasone intraoperatively after the skin incision and liposomal bupivacaine injected at surgery. Patients who did and did not use preoperative narcotics were analyzed together and separately. We evaluated hospitalization length of stay, narcotic use, and visual analog scale pain before and after the change in the perioperative protocol. RESULTS Cohort 1 was hospitalized longer (2 vs. 1 day; P < .001), required more narcotics on postoperative day 1 (21.0 vs. 10.0 mg; P < .001) and days 0 and 1 cumulatively (30.5 vs. 17.5 mg; P = .001), and had more pain on postoperative days 0 (6.5 vs. 3.5; P < .001) and 1 (7.5 vs. 3.5; P < .001) than cohort 2. In patients using preoperative narcotics, cohort 2 had less pain on postoperative day 1 (3.5 vs. 7.0; P = .006), less cumulative narcotic use (20 vs. 58.5 mg; P = .03), and shorter hospitalization (1 vs. 2 days; P = .052) than cohort 1. CONCLUSION These changes to the perioperative shoulder arthroplasty protocol decreased hospitalization length of stay, narcotic requirement, and pain.