Panayiotis Christofilopoulos

Prevalence of Neurologic Lesions After Total Shoulder Arthroplasty

BACKGROUND Clinically evident neurologic injury of the involved limb after total shoulder arthroplasty is not uncommon, but the subclinical prevalence is unknown. The purposes of this prospective study were to determine the subclinical prevalence of neurologic lesions after reverse shoulder arthroplasty and anatomic shoulder arthroplasty, and to evaluate the correlation of neurologic injury to postoperative lengthening of the arm. METHODS All patients undergoing either a reverse or an anatomic shoulder arthroplasty were included during the period studied. This study focused on the clinical, radiographic, and preoperative and postoperative electromyographic evaluation, with measurement of arm lengthening in patients who had reverse shoulder arthroplasty according to a previously validated protocol. RESULTS Between November 2007 and February 2009, forty-one patients (forty-two shoulders) underwent reverse shoulder arthroplasty (nineteen shoulders) or anatomic primary shoulder arthroplasty (twenty-three shoulders). The two groups were similar with respect to sex distribution, preoperative neurologic lesions, and Constant score. Electromyography performed at a mean of 3.6 weeks postoperatively in the reverse shoulder arthroplasty group showed subclinical electromyographic changes in nine shoulders, involving mainly the axillary nerve; eight resolved in less than six months. In the anatomic shoulder arthroplasty group, a brachial plexus lesion was evident in one shoulder. The prevalence of acute postoperative nerve injury was significantly more frequent in the reverse shoulder arthroplasty group (p = 0.002), with a 10.9 times higher risk (95% confidence interval, 1.5 to 78.5). Mean lengthening (and standard deviation) of the arm after reverse shoulder arthroplasty was 2.7 ± 1.8 cm (range, 0 to 5.9 cm) compared with the normal, contralateral side. CONCLUSIONS The occurrence of peripheral neurologic lesions following reverse shoulder arthroplasty is relatively common, but usually transient. Arm lengthening with a reverse shoulder arthroplasty may be responsible for these nerve injuries.

Acromioclavicular and coracoclavicular cerclage reconstruction for acute acromioclavicular joint dislocations

BACKGROUND Little information is available on the results of the different stabilization techniques described for treatment of acute acromioclavicular (AC) joint injuries. Additionally, no studies have analyzed isometric performance of the shoulder after AC stabilization. The objective of our study was to present functional outcome including isokinetic testing and radiographic evaluation of patients treated with stabilization of AC joint dislocations. PATIENTS AND METHODS Thirty-seven patients with acute type III to V AC joint disruption underwent open coracoclavicular (CC) and AC stabilization with nonabsorbable sutures. RESULTS The mean follow-up was 4.5 ± 2.5 years (range, 2-10.5). The mean Constant score (CS) was 96. There were 34 (91.9%) excellent results, 1 good (2.7%), 1 satisfactory (2.7%), and 1 fair (2.7%). The disabilities of the arm, shoulder, and hand (DASH) questionnaire revealed good overall subjective evaluation with a mean of 7 points. The mean visual analog scale (VAS) pain score was 0.8. Patients with a CC distance <5 mm, or an anterosuperior AC reduction less than 50%, showed significantly better results in CS and DASH score in comparison to patients with a subluxated AC joint (P < .005). Twenty-two patients agreed to undergo isokinetic evaluation. We were unable to demonstrate any clinically significant difference between the involved and the uninvolved side. DISCUSSION The described technique of cerclage augmentation offers an attractive alternative in AC joint stabilization, with good to excellent results. In comparison to other techniques, there were no complications related to any implants, no graft donor site morbidity, or need for implant removal.

Microencapsulated human mesenchymal stem cells decrease liver fibrosis in mice

BACKGROUND & AIMS Mesenchymal stem cell (MSC) transplantation was shown to be effective for the treatment of liver fibrosis, but the mechanisms of action are not yet fully understood. We transplanted encapsulated human MSCs in two mouse models of liver fibrosis to determine the mechanisms behind the protective effect. METHODS Human bone marrow-derived MSCs were microencapsulated in novel alginate-polyethylene glycol microspheres. In vitro, we analyzed the effect of MSC-conditioned medium on the activation of hepatic stellate cells and the viability, proliferation, cytokine secretion, and differentiation capacity of encapsulated MSCs. The level of fibrosis induced by bile duct ligation (BDL) or carbon tetrachloride (CCl4) was assessed after intraperitoneal transplantation of encapsulated MSCs, encapsulated human fibroblasts, and empty microspheres. RESULTS MSC-conditioned medium inhibited hepatic stellate cell activation and release of MSC secreted anti-apoptotic (IL-6, IGFBP-2) and anti-inflammatory (IL-1Ra) cytokines. Viability, proliferation, and cytokine secretion of microencapsulated MSCs were similar to those of non-encapsulated MSCs. Within the microspheres, MSCs maintained their capacity to differentiate into adipocytes, chondrocytes, and osteocytes. 23% (5/22) of the MSC clones were able to produce anti-inflammatory IL-1Ra in vitro. Microencapsulated MSCs significantly delayed the development of BDL- and CCl4-induced liver fibrosis. Fibroblasts had an intermediate effect against CCl4-induced fibrosis. Mice transplanted with encapsulated MSCs showed lower mRNA levels of collagen type I, whereas levels of matrix metalloproteinase 9 were significantly higher. Human IL-1Ra was detected in the serum of 36% (4/11) of the mice transplanted with microencapsulated MSCs. CONCLUSIONS MSC-derived soluble molecules are responsible for an anti-fibrotic effect in experimental liver fibrosis.

Sexual activity after total hip arthroplasty: a motion capture study.

Relative risk of impingement and joint instability during sexual activities after total hip arthroplasty (THA) has never been objectively investigated. Hip range of motion necessary to perform sexual positions is unknown. A motion capture study with two volunteers was performed. 12 common sexual positions were captured and relevant hip joint kinematics calculated. The recorded data were applied to prosthetic hip 3D models to evaluate impingement and joint instability during motion. To explore the effect of acetabular component positioning, nine acetabular cup positions were tested. Four sexual positions for women requiring intensive flexion (> 95°) caused prosthetic impingements (associated with posterior instability) at 6 cup positions. Bony impingements (associated with anterior instability) occurred during one sexual position for men requiring high degree of external rotation (> 40°) combined with extension and adduction at all cup positions. This study hence indicates that some sexual positions could be potentially at risk after THA, particularly for women.

The potential role of cobalt ions released from metal prosthesis on the inhibition of Hv1 proton channels and the decrease in Staphyloccocus epidermidis killing by human neutrophils

Infection by Staphylococcus epidermidis is a devastating complication of metal-on-metal (MM) total hip arthroplasty (THA). Neutrophils are the first line of defense against infection, and these innate immune cells are potentially exposed to Co(2+) ions released in the peri-prosthetic tissue by the wear of MM THA. The toxicity of Co(2+) is still debated, but Co(2+) is a potential inhibitor of the Hv1 proton channel that sustains the production of superoxide by neutrophils. In this study, we show that the Co(2+) concentration in peri-prosthetic tissue from patients with MM THA averages 53 μM and that such high concentrations of Co(2+) alter the antibacterial activity of human neutrophils in vitro by inhibiting Hv1 proton channels. We show that submillimolar concentrations of Co(2+) inhibit proton currents, impair the extrusion of cytosolic acid, and decrease the production of superoxide in human neutrophils. As a result, Co(2+) reduces the ability of human neutrophils to kill two strains of Staphyloccocus epidermidis by up to 7-fold at the maximal concentration tested of 100 μM Co(2+). By inhibiting proton channels, the Co(2+) ions released by metal prostheses might therefore promote bacterial infections in patients with metal-on-metal total hip arthroplasty.

Body mass and weight thresholds for increased prosthetic joint infection rates after primary total joint arthroplasty

Background and purpose — Obesity increases the risk of deep infection after total joint arthroplasty (TJA). Our objective was to determine whether there may be body mass index (BMI) and weight thresholds indicating a higher prosthetic joint infection rate. Patients and methods — We included all 9,061 primary hip and knee arthroplasties (mean age 70 years, 61% women) performed between March 1996 and December 2013 where the patient had received intravenous cefuroxime (1.5 g) perioperatively. The main exposures of interest were BMI (5 categories: < 24.9, 25–29.9, 30–34.9, 35–39.9, and ≥ 40) and weight (5 categories: < 60, 60–79, 80–99, 100–119, and ≥ 120 kg). Numbers of TJAs according to BMI categories (lowest to highest) were as follows: 2,956, 3,350, 1,908, 633, and 214, respectively. The main outcome was prosthetic joint infection. The mean follow-up time was 6.5 years (0.5–18 years). Results — 111 prosthetic joint infections were observed: 68 postoperative, 16 hematogenous, and 27 of undetermined cause. Incidence rates were similar in the first 3 BMI categories (< 35), but they were twice as high with BMI 35–39.9 (adjusted HR = 2.1, 95% CI: 1.1–4.3) and 4 times higher with BMI ≥ 40 (adjusted HR = 4.2, 95% CI: 1.8–9.7). Weight ≥ 100 kg was identified as threshold for a significant increase in infection from the early postoperative period onward (adjusted HR = 2.1, 95% CI: 1.3–3.6). Interpretation — BMI ≥ 35 or weight ≥ 100 kg may serve as a cutoff for higher perioperative dosage of antibiotics.

Pseudoaneurysm of the anterior tibial artery following an ankle sprain: A case report of an uncommon ankle trauma with review of the literature

Ankle sprains are common injuries and often result from inversion of the foot due to a low energy accident. In most cases the lateral collateral ligaments are injured. However, in addition to injury to the musculoskeletal system the sprain may also involve the surrounding neurovascular structures. This report concerns an uncommon associated lesion, a pseudoaneurysm of the anterior tibial artery following an ankle sprain. Review of the literature reveals few cases of vascular injury around the ankle joint due to low energy trauma without a specific consensus for their treatment.

Strong association between smoking and the risk of revision in a cohort study of patients with metal-on-metal total hip arthroplasty

Thus far the ability to predict who will develop early failure following the insertion of a metal‐on‐metal (MoM) bearing has been very limited. Our objective was to assess the effect of smoking on failure rates in patients with MoM bearing, compared with patients with ceramic‐on‐polyethylene (CoP) bearing. From a prospective hospital‐based registry we included all primary THAs operated upon between 1/2001 and 12/2011 with MoM or CoP bearings of the same cup design and head size (28 mm). We compared revision rates through 10/2013 classified by smoking status and type of bearing. We included 1,964 patients (median age 71, 57% women), 663 with MoM and 1,301 with CoP bearing. Mean follow‐up was 6.9 years (range 1.8–12.8). Revisions were required for 56 THAs. In patients with MoM bearing the adjusted incidence rate of revision among ever‐smokers was four times greater than among never‐smokers (95% CI 1.4–10.9). Among those with CoP bearing, the rate ratio was only 1.3 (95% CI 0.6–2.5). We found a strong association between smoking and increased failure of MoM THAs. In contrast, the association was weak for patients with CoP bearing. Smoking might be a trigger or an effect amplifier for adverse reactions to metal debris from MoM bearings.

Augmented osteosynthesis of OTA 44-B fractures in older patients: a technique allowing early weightbearing.

Objectives: To determine the effectiveness of an augmented technique of osteosynthesis in allowing early weightbearing in older patients with OTA 44-B (Danis-Weber B) fractures. Design: Case series. Setting: University Level I trauma center. Patients: Thirty-six patients, nonconsecutive, with OTA 44-B fractures. Intervention: Augmented internal fixation using an intramedullary wire, lateral plate, and screw augmentation with polymethylmethacrylate. Outcome Measures: Main outcome: Healed fracture with no loss of reduction. Secondary outcomes: American Orthopaedic Foot and Ankle Society score; percentage of patients who returned to prefracture function. Results: All patients began weightbearing as tolerated in a removable brace at a mean of 13.5 days postoperatively. Thirty patients were available for follow-up at a minimum of 12 months (range, 12–14 months). All fractures healed with no loss of reduction. The mean American Orthopaedic Foot and Ankle Society ankle–hindfoot score was 84.9 (range, 74–100), and 90% of patients returned to prefracture function. There were two infections, one in a 74-year-old diabetic woman and the other in a 92-year-old woman with pre-existing arterial insufficiency and a small ulcer over the tip of the second toe. Conclusions: Augmented internal fixation consisting of intramedullary wire, lateral plate, and screw augmentation with polymethylmethacrylate may allow for very early weightbearing without risk of secondary loss of reduction or disruption of the ankle mortise in older patients with OTA 44-B (Danis-Weber B) malleolar fractures.

Nerve injuries in total hip arthroplasty with a mini invasive anterior approach

Purpose Minimal invasive techniques in total hip arthroplasty (THA) have become increasingly popular during recent years. Despite much debate over the outcome of several minimal invasive techniques, complications arising from the use of anterior minimally invasive surgery (AMIS) for THA on a traction table are not well documented. Our study aims to focus on nerve damage during the AMIS procedure and the possible explanations of these injuries. Methods We reviewed all primary THAs performed with the AMIS technique using a traction table, over 5 years and recorded all intraoperative and postoperative complications up to the latest follow-up. We focused on nerve injuries and nerve function impairment following the aforementioned technique. Results Our study included 1,512 THAs performed with the AMIS technique in 2 major hip reconstruction centres (KAT General Hospital, Athens, Greece and University Hospital of Geneva, Switzerland), on 1,238 patients (985 women, 253 men; mean age 65.24 years). Mean follow-up was 29.4 months. We observed 51 cases of transient lateral femoral cutaneous nerve neuropraxia (3.37%), 4 cases of femoral nerve paralysis (3 permanent, 1 transient [0.26%]) and 1 case of permanent sciatic nerve paralysis (0.06%). No case of obturator or pudendal nerve injury was noticed. Mean age of these cases was 68.97 years. Sciatic and femoral nerve injuries were confirmed by electromyography, showing axonotmesis of the damaged nerve. Conclusions Neurological injuries are a rare but distinct complication of THAs using the AMIS technique. Possible explanations for such referred nerve injuries are direct nerve injury, extreme traction, hyperextension, extreme external rotation of the leg, use of retractors and coexisting spinal deformities. Controlled use of traction in hip extension, cautious use of retractors and potential use of dynamometers may be useful, so that neurological damage can be avoided. Further studies are needed to fully elucidate the role of the above factors in AMIS neurological complications.