Angela D. Keith

Does Previous Osteotomy Compromise Total Hip Arthroplasty? A Systematic Review

Hip osteotomy surgery has increased over the past several years, yet the impact of these procedures on subsequent total hip arthroplasty (THA) remains controversial. The purpose of this study was to perform a systematic review of the literature to determine the clinical results, procedure complications, and survivorship of THA following previous hip osteotomy. Ten studies met inclusion criteria. The operative time and estimated blood loss were higher in the post-osteotomy cohorts; while the clinical results and survivorship between groups were similar. THA following previous pelvic and femoral osteotomy provides pain relief and improved function with similar complication rates, clinical outcomes, and survivorship compared to hips undergoing routine primary THA. These procedures can be technically more demanding with increased operative times and intraoperative blood loss.

Relationship Between Mitochondrial Matrix Volume and Cellular Volume in Response to Stress and the Role of ATP-Sensitive Potassium Channel

Background— Cardiac myocytes demonstrate significant swelling and associated reduced contractility in response to stress that is prevented by the ATP-sensitive potassium channel opener, diazoxide (DZX) via an unknown mechanism. One proposed mechanism of cardioprotection is mitochondrial matrix swelling. To establish the relationship between mitochondrial and cellular volume during stress, this study examined the effect of DZX on mitochondrial volume. Methods and Results— Isolated mouse mitochondria were exposed to the following solutions: Tyrode, isolation buffer, cardioplegia (CPG)±DZX±ATP-sensitive potassium channel inhibitor, 5-hydroxydecanoate, and metabolic inhibition (MI)±DZX±5-hydroxydecanoate. Mitochondrial volume was measured. DZX resulted in significant mitochondrial swelling (P<0.0001 versus Tyrode). MI and CPG resulted in significant mitochondrial swelling compared with baseline volume. The addition of DZX did not alter the response of mitochondrial volume to CPG (P=0.912) but increased swelling in response to MI (P=0.036). The addition of 5-hydroxydecanoate to MI+DZX or CPG+DZX significantly reduced mitochondrial swelling (P<0.003 MI+DZX versus MI+DZX+5HD; P<0.001 CPG+DZX versus CPG+DZX+5HD). Conclusions— Both cellular and mitochondrial volume increased during exposure to MI and CPG. DZX did not alter mitochondrial volume during CPG; however, it was associated with an increase in mitochondrial volume during MI. 5-Hydroxydecanoate reduced mitochondrial volume during exposure to both stresses with DZX, supporting a role for a mitochondrial ATP-sensitive potassium channel in the mechanism of cardioprotection by DZX.

Cardioprotective mechanism of diazoxide involves the inhibition of succinate dehydrogenase

BACKGROUND The adenosine triphosphate-sensitive potassium (KATP) channel opener, diazoxide, preserves myocyte volume homeostasis and contractility during stress via an unknown mechanism. Pharmacologic overlap has been suggested between succinate dehydrogenase (SDH) activity and KATP channel modulators. Diazoxide may be cardioprotective due to the inhibition of SDH which may form a portion of the mitochondrial KATP channel. To determine the role of inhibition of SDH in diazoxides cardioprotection, this study utilized glutathione to prevent the inhibition of SDH. METHODS SDH activity was measured in isolated mitochondria exposed to succinate (control), malonate (inhibitor of succinate dehydrogenase), diazoxide, and varying concentrations of glutathione alone or in combination with diazoxide. Enzyme activity was measured by spectrophotometric analysis. To evaluate myocyte volume and contractility, cardiac myocytes were superfused with Tyrodes physiologic solution (Tyrodes) (20 minutes), followed by test solution (20 minutes), including Tyrodes, hyperkalemic cardioplegia (stress), cardioplegia + diazoxide, cardioplegia + diazoxide + glutathione, or glutathione alone; followed by Tyrodes (20 minutes). Myocyte volume and contractility were recorded using image grabbing software. RESULTS Both malonate and diazoxide inhibited succinate dehydrogenase. Glutathione prevented the inhibition of succinate dehydrogenase by diazoxide in a dose-dependent manner. The addition of diazoxide prevented the detrimental myocyte swelling due to cardioplegia alone and this benefit was lost with the addition of glutathione. However, glutathione elicited an independent cardioprotective effect on myocyte contractility. CONCLUSIONS The ability of diazoxide to provide beneficial myocyte homeostasis during stress involves the inhibition of succinate dehydrogenase, which may also involve the opening of a purported mitochondrial adenosine triphosphate sensitive potassium channel.

Early Clinical and Radiographic Outcomes of Combined Hip Arthroscopy and Periacetabular Osteotomy.

Objectives: Modern treatment of hip dysplasia has focused on the correction of the structural deformity with the periacetabular osteotomy (PAO), which addresses the deformity by redirecting the acetabulum into an improved mechanical position. Hip arthroscopy has allowed an increased awareness of the intra-articular pathology associated with acetabular dysplasia. The combination of hip arthroscopy with periacetabular osteotomy allows for treatment of both intra-articular and structural abnormalities associated with hip dysplasia. However, there is limited information regarding this combined approach for treating symptomatic acetabular dysplasia. The purpose of this study was to report the early clinical and radiographic outcomes of combining hip arthroscopy with PAO compared to PAO alone. Methods: We retrospectively reviewed 48 hips (46 patients) who underwent hip arthroscopy combined with periacetabular osteotomy (HS-PAO) and compared them to a control group of 62 hips (54 patients) who underwent PAO alone. The minimum clinical follow-up of the HS-PAO group was 12 months (mean, 31.4 months; range, 12-79 months), which was not significantly different from the control group (mean, 28.7 months; range, 12-71 months; p = 0.39). Pre-operative and post-operative standardized radiographs were analyzed for findings of acetabular dysplasia, including lateral center-edge angle (LCEA), acetabular inclination, anterior-center edge angle (ACEA), and Tönnis osteoarthritis grade. Clinical outcomes were evaluated with the UCLA activity score, modified Harris hip score (mHHS), short form-12 (SF-12), and the Western Ontario and McMaster Universities Arthritis Index (WOMAC). Perioperative complications were graded and compared between the two groups. Results: The mean age of the patients in the HS-PAO group was 28.0 years (range, 12 to 47 years), which was not significantly different from the control group (p = 0.35). Forty-four hips (91.7%) were in female patients, and 58% were right-sided. There was significant change in the mean LCEA (15.1° vs. 29.7°; p < 0.0001), acetabular inclination (15.0° vs. 2.8°; p < 0.0001), and ACEA (16.5° vs. 33.7°; p <0.0001). The preoperative UCLA, mHHS, and SF-12 scores were not significantly different between groups. The HS-PAO group had a significantly higher pre-operative total WOMAC score (40.6 vs. 30.8; p = 0.03). The HS-PAO and control groups both saw significant improvement in the mHHS (23.5 vs. 21.3), SF-12 physical (7.5 vs. 9.1) scores, which were not significantly different from each other (all p-values > 0.3). The PAO-HS group, however, experienced a 0.9 improvement in the UCLA score, which was significantly different from the control group (-0.2; p = 0.03). The PAO-HS group also experienced a significantly greater improvement in the total WOMAC score (27.0 vs. 17.8; p = 0.03). There were no significant differences in the complication between the groups. Within the PAO-HS group, there were 16 lateral femoral cutaneous nerve palsies (33.3%) that resolved with outpatient management. There was 1 posterior column fracture that was treated nonoperatively. Conclusion: At short-term follow-up, hip arthroscopy with PAO shows equal to improved clinical outcomes with similar radiographic changes when compared to PAO alone without an increase in major complications. Patients that underwent hip arthroscopy combined with PAO also experienced a larger increase in activity level when compared to PAO alone.