Reverse shoulder arthroplasty has a higher risk of revision due to infection than anatomical shoulder arthroplasty: 17 730 primary shoulder arthroplasties from the Nordic Arthroplasty Register Association.

AIMS: The aim of this study was to use national registry database information to estimate cumulative rates and relative risk of revision due to infection after reverse shoulder arthroplasty. PATIENTS AND METHODS: We included 17 730 primary shoulder arthroplasties recorded between 2004 and 2013 in The Nordic Arthroplasty Register Association (NARA) data set. With the Kaplan-Meier method, we illustrated the ten-year cumulative rates of revision due to infection and with the Cox regression model, we reported the hazard ratios as a measure of the relative risk of revision due to infection. RESULTS: In all, 188 revisions were reported due to infection during a mean follow-up of three years and nine months. The ten-year cumulative rate of revision due to infection was 1.4% overall, but 3.1% for reverse shoulder arthroplasties and 8.0% for reverse shoulder arthroplasties in men. Reverse shoulder arthroplasties were associated with an increased risk of revision due to infection also when adjusted for sex, age, primary diagnosis, and year of surgery (relative risk 2.41 (95% confidence interval 1.26 to 5.59); p = 0.001). CONCLUSION: The overall incidence of revision due to infection was low. The increased risk in reverse shoulder arthroplasty must be borne in mind, especially when offering it to men. Cite this article: Bone Joint J 2019;101-B:702-707.

Intermittent pneumatic compression reduces the risk of deep vein thrombosis during post-operative lower limb immobilisation: a prospective randomised trial of acute ruptures of the Achilles tendon.

Deep vein thrombosis is a common complication of immobilising the lower limb after surgery. We hypothesised that intermittent pneumatic compression (IPC) therapy in outpatients who had undergone surgical repair of acute ruptures of the Achilles tendon could reduce the incidence of this problem. A total of 150 patients who had undergone surgical repair of the Achilles tendon were randomised to either treatment with IPC for six hours per day (n = 74) under an orthosis or treatment as usual (n = 74) in a plaster cast without IPC. At two weeks post-operatively, the incidence of deep vein thrombosis was assessed using blinded, double-reported compression duplex ultrasound. At this point, IPC was discontinued and all patients were immobilised in an orthosis for a further four weeks. At six weeks post-operatively, a second compression duplex ultrasound scan was performed. At two weeks, the incidence of deep vein thrombosis was 21% in the treated group and 37% in the control group (p = 0.042). Age over 39 years was found to be a strong risk factor for deep vein thrombosis (odds ratio (OR) = 4.84, 95% confidence interval (CI) 2.14 to 10.96). Treatment with IPC, corrected for age differences between groups, reduced the risk of deep vein thrombosis at the two-week point (OR = 2.60; 95% CI 1.15 to 5.91; p =0.022). At six weeks, the incidence of deep vein thrombosis was 52% in the treated group and 48% in the control group (OR 0.94, 95% CI 0.49 to 1.83). IPC appears to be an effective method of reducing the risk of deep vein thrombosis in the early stages of post-operative immobilisation of outpatients. Further research is necessary to elucidate whether it can confer similar benefits over longer periods of immobilisation and in a more heterogeneous group of patients.

Can foot compression under a plaster cast prevent deep-vein thrombosis during lower limb immobilisation?

We hypothesised that adjuvant intermittent pneumatic compression (IPC) beneath a plaster cast would reduce the risk of deep-vein thrombosis (DVT) during post-operative immobilisation of the lower limb. Of 87 patients with acute tendo Achillis (TA) rupture, 26 were prospectively randomised post-operatively after open TA repair. The treatment group (n = 14) received two weeks of IPC of the foot for at least six hours daily under a plaster cast. The control group (n = 12) had no additional treatment. At two weeks post-operatively all patients received an orthosis until follow-up at six weeks. At two and six weeks the incidence of DVT was assessed using colour duplex sonography by two ultrasonographers blinded to the treatment. Two patients withdrew from the study due to inability to tolerate IPC treatment. An interim analysis demonstrated a high incidence of DVT in both the IPC group (9 of 12, 75%) and the controls (6 of 12, 50%) (p = 0.18). No significant differences in incidence were detected at two (p = 0.33) or six weeks (p = 0.08) post-operatively. Malfunction of the IPC leading to a second plaster cast was found to correlate with an increased DVT risk at two weeks (ϕ = 0.71; p = 0.019), leading to a premature abandonment of the study. We cannot recommend adjuvant treatment with foot IPC under a plaster cast for outpatient DVT prevention during post-operative immobilisation, owing to a high incidence of DVT related to malfunctioning of this type of IPC application.

Anti-inflammatory cytokine profile in early human tendon repair.

PURPOSE: The aim of this study was to assess inflammation and the presence and relative levels of cytokines, which may be involved in regulating early human Achilles tendon healing. METHODS: Nine patients with acute Achilles tendon rupture were included, operated on and post-operatively immobilized. Two weeks post-operatively, microdialysis of the peritendinous interstitial compartment was performed in the healing and intact contralateral Achilles tendons. Quantification of tumour necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-1ß, IL-6, IL-8, IL-10, IL-12p70 and IL-17A was accomplished using a cytometric bead array. Prostaglandin (PG) E2 levels were measured by enzyme immunoassay. RESULTS: None of the patients displayed detectable PGE2 levels. Pro-inflammatory cytokines were below detection levels (IFNγ, IL-12, and IL-17) or did not differ between injured and control tendons (IL-1ß and TNF). Notably, IL-6, IL-8 and IL-10 concentrations in the healing Achilles tendon were significantly elevated: 13-fold (p = 0.009), 28-fold (p = 0.02), and 3.7-fold (p = 0.03), respectively. CONCLUSION: At 2 weeks post-human Achilles tendon rupture, healing is characterized by a resolving inflammatory phase and up-regulation of IL-6, IL-8 and IL-10. The absence of inflammation suggests that at this time point, these cytokines may be associated with anti-inflammatory and regenerative effects on the tendon healing process.

Metabolic activity in early tendon repair can be enhanced by intermittent pneumatic compression.

Since Achilles tendon healing is protracted, more knowledge of metabolites known to meet the demands for biosynthesis and proliferation is needed. We hypothesized that essential metabolites, glutamate, glucose, lactate, pyruvate and glycerol, are present and upregulated in healing Achilles tendons. We moreover hypothesized that adjuvant intermittent pneumatic compression (IPC), which increases blood flow, upregulates metabolite concentrations. Twenty patients with acute Achilles tendon rupture were recruited, operated, and included. The control group, 15 patients, received plaster cast immobilization, while five patients received adjuvant foot IPC beneath the plaster cast. At 2 weeks postoperatively, microdialysis of the healing and contralateral intact Achilles tendons was followed by quantification of metabolites. Healing compared to intact tendons of the controls exhibited significantly increased concentrations (mM) of glutamate (60 ± 14 vs 20 ± 11), lactate (1.15 ± 0.60 vs 0.64 ± 0.35), and pyruvate (81 ± 29 vs 35 ± 25, µM). Healing tendons of the IPC vs control group displayed higher levels of glutamate (84 ± 15 vs 62 ± 16) and glucose (3.44 ± 0.62 vs 2.62 ± 0.72); (P < 0.05) and trends toward higher concentrations of pyruvate, lactate, and glycerol (P < 0.10). The present study demonstrates that early Achilles tendon repair entails and upregulates local essential metabolites. This metabolic response can, during tendon healing with plaster cast immobilization, be promoted by adjuvant IPC.