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Introduction While the management of Rockwood type III injuries is still a topic of debate, high-grade Rockwood type V injuries are mostly treated surgically, to anatomically reduce the acromioclavicular (AC) joint and to restore functionality. In this case report, we present a method for non-operative reduction and stabilization of a high-grade AC joint injury. Case A 31-year-old male orthopaedic resident sustained a Rockwood type V injury during a snowboarding accident. His AC joint was reduced and stabilized with an AC joint brace for six weeks. The brace provided active clavicle depression and humeral elevation. After removal of the brace the AC joint showed a nearly anatomic reduction. Six-month follow-up weighted X-ray views showed an AC joint which had healed in a Rockwood type II position and the patient returned to full pre-injury function with a satisfying cosmetic appearance. Conclusion Non-operative reduction and stabilization of high-grade AC joint separations seems to be a valuable treatment option. A “closed reduction and external fixation” approach with the aid of a dedicated AC joint brace can reduce the AC joint and keep it in place until ligamentous consolidation occurs, thus improving AC joint stability and cosmetic appearance without surgical intervention.

Reinfection after two-stage exchange arthroplasty is a difficult clinical scenario with limited data on adequate treatment algorithms. Beside the possibility of treatment failure and a new intraoperative infection at the time of reimplantation, hematogenous seeding could play an up to date underestimated crucial role as another cause of an infection after two-stage exchange. The aim of this study was to evaluate its incidence and treatment possibilities in a prospectively followed case series. All consecutive hip and knee periprosthetic joint infection cases (93 hips and 89 knees) treated according to a standardized diagnostic and therapeutic algorithm at our institution with a two-stage exchange arthroplasty from 2013 to 2015 were included and followed prospectively to identify recurrent infections due to hematogenous seeding. Six percent from our septic revision hip and knee arthroplasties (11 of 182, including 5 hips and 6 knees) were identified with a hematogenous reinfection after a mean follow-up of 31.8 months (range 14–48 months). The mean time to reinfection after reimplantation was 12.2 months (range 3.1–35.1). In all but two cases was the causative microorganism different than isolated at the time of initial two-stage exchange. In 5 of 11 patients, the primary focus of infection was identified. Hematogenous infection after a successful two-stage exchange arthroplasty is a rare but very important cause of a reinfection. With our work, we aim at raising the awareness for this entity and recommend consideration of irrigation and debridement with implant retention in these cases, as well as possibly the identification of a primary infection source.

Introduction: The aim of this study was to analyse the relationship between bony joint orientation and the distribution of hip musculature. Methods: The bone anatomy of the hip (femoral antetorsion (AT), acetabular anteversion (AV), and combined anteversion (AV/AT)) and the muscle volume of the gluteal muscles and the tensor fasciae latae were analysed bilaterally using computed tomography data of 49 patients. Muscle force direction (MFD) was determined for each muscle. The total MFD of the hip musculature was calculated and then correlated with the bony anatomy. Results: The mean AV, AT, and AV/AT were 21.9° ± 5.9°, 7.22° ± 7.4°, and 29.2° ± 9°, respectively. We found the following mean muscle volumes: gluteus maximus: 780 ± 227 cm3, gluteus medius: 322 ± 82 cm3, gluteus minimus: 85 ± 20 cm3, and tensor fasciae latae: 68 ± 22 cm3. The mean MFD was 18.92° ± 1.29°. We found a uniform distribution of the musculature that was not correlated with the bone anatomy. Conclusion: This study highlights the variability in native acetabular and femoral anatomy and that bone hip anatomy does not correlate with the distribution of hip musculature. Although native acetabular anteversion matches the suggested targets for cup insertion, native combined anteversion is not related to current implant insertion targets. Understanding native muscular anatomy and the alterations that occur with different surgical approaches can serve as an explanatory model for THAs that has become unstable despite the components being implanted within the safe zone.

Aims The aim of this study was to identify the incidence of positive cultures during the second stage of a two-stage revision arthroplasty and to analyse the association between positive cultures and an infection-free outcome. Patients and Methods This single-centre retrospective review of prospectively collected data included patients with a periprosthetic joint infection (PJI) of either the hip or the knee between 2013 and 2015, who were treated using a standardised diagnostic and therapeutic algorithm with two-stage exchange. Failure of treatment was assessed according to a definition determined by a Delphi-based consensus. Logistic regression analysis was performed to assess the predictors of positive culture and risk factors for failure. The mean follow-up was 33 months (24 to 48). Results A total of 163 two-stage revision arthroplasties involving 84 total hip arthroplasties (THAs) and 79 total knee arthroplasties (TKAs) were reviewed. In 27 patients (16.6%), ≥ 1 positive culture was identified at re-implantation and eight (29.6%) of these subsequently failed compared with 20 (14.7%) patients who were culture-negative. The same initially infecting organism was isolated at re-implantation in nine of 27 patients (33.3%). The organism causing re-infection in none of the patients was the same as that isolated at re-implantation. The risk of the failure of treatment was significantly higher in patients with a positive culture (odds ratio (OR) 1.7; 95% confidence interval (CI) 1.0 to 3.0; p = 0.049) and in patients with a higher Charlson Comorbidity Index (OR 1.5; 95% CI 1.6 to 1.8; p = 0.001). Conclusion Positive culture at re-implantation was independently associated with subsequent failure. Surgeons need to be aware of this association and should consider the medical optimisation of patients with severe comorbidities both before and during treatment. Cite this article: Bone Joint J 2017;99-B:1490–5.

We present a 44-year-old male patient with new onset of right focal epilepsy and bilateral hand hypesthesia. Cerebral MRI showed bilateral T2w/DWI hyperintense subcortical lesions in the cingulate gyrus, insula, and amygdala, whereas spinal MRI revealed a cervical posterior column lesion, corresponding to subacute combined degeneration. Laboratory workup revealed a cobalamin deficiency due to type A gastritis, and no evidence of antibodies associated with limbic encephalitis. After sufficient cobalamin substitution, the cerebral and spinal lesions gradually regressed. Our case represents a unique cerebral subcortical MRI lesion pattern in a patient with epilepsy and cobalamin deficiency. Thus, the latter represents an important differential diagnosis for autoimmune encephalitis.

The simultaneous occurrence of periprosthetic fracture (PPF) and periprosthetic joint infection (PJI) is among the most devastating complications in arthroplasty and carries the risk of limb loss. For the first time, this study will describe the characteristics, treatment concepts, and outcomes of this complication. Patients were consecutively included who were treated at our specialized interdisciplinary department between 2015 and 2016 with a PJI and an additional PPF of the hip. The treatment algorithm followed a three-step procedure: the complete removal of any foreign material (step 1), fracture stabilization by plate, intramedullary rod osteosynthesis or cerclages using an additional spacer (step 2), and reimplantation of a new prosthesis (step 3). Overall, eight cases [four male, four female, mean age 77 years (55–91)] were included. The mean follow-up was 34 ± 8 months. The fractures included one PPF Vancouver B1, three B2/3, and four type C. Most frequent microbes were CNS (Coagulase-negative staphylococci) (n = 4), Cutibacterium (n = 2) and Staphylococcus aureus (n = 2). Mixed infections (≥ 2 microorganisms) occurred in five cases. The time between explanation and reimplantation was 42 ± 34 (range 7–123) days. A re-infection took place in one, a re-revision in four cases, and in five cases fracture healing was noticed. In all eight cases, freedom from the infection and limb preservation could be achieved. PPF in the case of a PJI is a devastating situation and a huge challenge. Extremity preservation should be the primary goal. The described procedure offers a possible solution.

Background Hip joint loading is dominated by muscular activity. Thus, contact forces exceeding many times one's body weight are a consequence of imbalanced muscular activity. The objective was to analyze the influence of muscle atrophy after total hip arthroplasty on in vivo hip joint contact loading initially and long term. We hypothesized that an impaired periarticular muscle will lead to increase in vivo joint load, specifically in the long term. Methods Using a group of nine patients with instrumented hip implants, contact forces and muscle status were analyzed one day prior to 3 and 50 months after joint arthroplasty. In vivo load measurements were performed for different activities of daily living (ADL). Pre- and postoperative pelvic CT scans were analyzed to assess the periarticular muscle status. Finally, the muscle morphologies and in vivo contact forces were compared. Results At 3 months after total hip arthroplasty we found a significant correlation of lower lean gluteus minimus muscle (GMin) volume with higher loads during all tested activities of daily living. 50 months postoperatively statistical analysis revealed lower lean volume of the gluteus maximus to be correlated with higher joint loads in walking. Conclusion Our data generally show a good comparability between muscle status and joint contact forces and thus support our hypothesis that an impairment of periarticular musculature contributes to an increase of the in vivo joint loads after total hip arthroplasty. Effects were most pronounced during stair climbing and sit-down/stand-up from a chair at 3 months and during level walking at 50 months.

Background Two-stage revision with static antibiotic spacers is the preferred treatment for chronically infected total knee arthroplasty (TKA) associated with severe bone loss. Intramedullary rods to reinforce static spacers have been described. On those, however, bacterial colonization may occur and hamper infection control. This study reports the microbiological findings on the spacer rods and the treatment outcome among these patients. Methods We reviewed 97 infected TKA with extensive bone loss treated with antibiotic-loaded cement spacers reinforced with intramedullary rods. Mean interim period with the spacer in situ was 9 weeks (range: 6-24 weeks). Intraoperative cultures and sonicated spacer rods were analyzed. Mean follow-up after TKA reimplantation was 41 months (range: 27-56 months). Treatment success was defined using the modified Delphi consensus criteria. Results Twenty-two patients (23%) had treatment failure, including 3 reinfections caused by the same organism, 9 reinfections caused by a different organism, 9 patients required interim spacer exchange, and 1 patient died in the early postoperative course. Sonication cultures of the spacer rods were positive in 2 cases (2%), and none of them failed. Host and limb status was significantly worse in patients who sustained reinfection. At the latest follow-up, all patients had a TKA in place, and 2 patients received chronic antibiotic suppression. Conclusion Two-stage revision with the use of intramedullary rods is a safe and efficient treatment for chronically infected TKA with severe bone loss. Most reinfections grew different organisms compared with initial infection. Compromised hosts and extremities may be subjected to chronic antibiotic suppression.

OBJECTIVE We tested the hypotheses (i) that autoimmune encephalitis is associated with new-onset headache, and (ii) that the occurrence of headache is associated with the presence of anti-N-methyl-D-aspartate (NMDA)-receptor antibodies. BACKGROUND Autoimmune encephalitis presents with cognitive dysfunction as well as neuro-psychiatric symptoms. Its pathophysiology might involve antibody-mediated dysfunction of the glutamatergic system as indicated by the presence of anti-NMDA-receptor antibodies in some patients. METHODS In this cross-sectional study, patients with autoimmune encephalitis were assessed with a standardized interview for previous headache and headache associated with autoimmune encephalitis. Headache was classified according to the International Classification of Headache Disorders, second edition. Clinical and paraclinical findings were correlated with the occurrence of headache. RESULTS Of 40 patients with autoimmune encephalitis, 19 did not have a history of headache. Of those, nine suffered from encephalitis-associated headache. Seven of these nine had anti-NMDA-receptor antibodies in contrast to only two among the remaining 10 patients without new-onset headache (P = .023, odds ratio: 14, 95% confidence interval: 1.5; 127). In most patients headache occurred in attacks on more than 15 days/month, was severe, and of short duration (less than 4 hours). International Headache Society criteria for migraine were met in three patients. CONCLUSIONS New-onset headache is a relevant symptom in patients with autoimmune encephalitis who have no history of previous headache, especially in the subgroup with anti-NMDA-receptor antibodies. This indicates a thorough investigation for secondary headaches including anti-NMDA-R antibodies for patients with new-onset headache and neuropsychiatric findings. Glutamatergic dysfunction might be important for the generation of head pain but may only occasionally be sufficient to trigger migraine-like attacks in nonmigraineurs.

Background Developmental dysplasia of the hip (DDH) can lead to pain and premature secondary osteoarthritis at an early stage. Joint-preserving osteotomy is an established solution to this problem. In contrast, a conservative approach would result in pain persistence, ultimately raising the patients question for a possible date of expected prosthesis implantation. The aim of the study was to identify the relationship between the dysplastic hip anatomy and the time of prosthesis implantation in order to enable prognostic predictions in younger patients with symptomatic DDH. Materials and methods Data from 129 hips who received THA due to secondary DDH osteoarthritis were evaluated. The preoperative hip anatomy was evaluated for AI and LCE angle. Multiple linear regression analyses were then used to correlate the influence of these parameters with the patient’s age at the time of surgery. In addition, a graphical relationship was derived by the method of power least squares curve fitting with second-degree polynomials. Results The mean age for THA was 54.3 ± 11 years. The time of surgery correlated significantly with LCE (0.37) and AI (− 0.3) (p

Background Two-stage exchange arthroplasty is still the preferred treatment choice for chronic PJI. However, the results remain unpredictable. We analyzed the treatment success of patients with an infected hip prosthesis, who were treated according to a standardized algorithm with a multidisciplinary team approach and evaluated with a strict definition of failure. Methods In this single-center prospective cohort study, all hip PJI episodes from March 2013 to May 2015 were included. Treatment failure was assessed according to the Delphi-based consensus definition. The Kaplan-Meier survival method was used to estimate the probability of infection-free survival. Patients were dichotomized into two groups depending on the number of previous septic revisions, duration of prosthesis-free interval, positive culture with difficult-to-treat microorganisms, microbiology at explantation, and microbiology at reimplantation. Results Eighty-four patients with hip PJI were the subject of this study. The most common isolated microorganisms were coagulase-negative staphylococci (CNS) followed by Staphylococcus aureus and Propionibacterium. Almost half of the study cohort (46%) had at least one previous septic revision before admission. The Kaplan-Meier estimated infection-free survival after 3 years was 89.3% (95% CI, 80% to 94%) with 30 patients at risk. The mean follow-up was 33.1 months (range, 24–48 months) with successful treatment of PJI. There were no statistical differences in infect eradication rate among the dichotomized groups. Conclusions High infect eradication rates were achieved in a challenging cohort using a standardized two-stage exchange supported by a multidisciplinary approach.

Aims The aim of this study was to determine the prevalence and characteristics of C-reactive protein (CRP)-negative prosthetic joint infection (PJI) and evaluate the influence of the type of infecting organism on the CRP level. Patients and Methods A retrospective analysis of all PJIs affecting the hip or knee that were diagnosed in our institution between March 2013 and December 2016 was performed. A total of 215 patients were included. Their mean age was 71 years (sd 11) and there were 118 women (55%). The median serum CRP levels were calculated for various species of organism and for patients with acute postoperative, acute haematogenous, and chronic infections. These were compared using the Kruskal–Wallis test, adjusting for multiple comparisons with Dunn’s test. The correlation between the number of positive cultures and serum CRP levels was estimated using Spearman correlation coefficient. Results Preoperative CRP levels were normal (< 10 mg/l) in 77 patients (35.8%) with positive cultures. Low-virulent organisms were isolated in 66 PJIs (85.7%) with normal CRP levels. When grouping organisms by species, patients with an infection caused by Propionibacterium spp., coagulase-negative staphylococci (CNS), and Enterococcus faecalis had significantly lower median serum CRP levels (5.4 mg/l, 12.2 mg/l, and 23.7 mg/l, respectively), compared with those with infections caused by Staphylococcus aureus and Streptococcus spp. (194 mg/l and 89.3 mg/l, respectively; p < 0.001). Those with a chronic PJI had statistically lower median serum CRP levels (10.6 mg/l) than those with acute postoperative and acute haematogenous infections (83.7 mg/l and 149.4 mg/l, respectively; p < 0.001). There was a significant correlation between the number of positive cultures and serum CRP levels (Spearman correlation coefficient, 0.456; p < 0.001). Conclusion The CRP level alone is not accurate as a screening tool for PJI and may yield high false-negative rates, especially if the causative organism has low virulence. Aspiration of the joint should be used for the diagnosis of PJI in patients with a chronic painful arthroplasty, irrespective of CRP level. Cite this article: Bone Joint J 2018;100-B:1482–86.

Background Total hip arthroplasty (THA) is in most cases improving patients´ life quality immediately after surgery. However, a closer look at these patients, especially with modern gait analysis methods, reveals also negative consequences due to the surgical approach related injury to the pelvic muscles. We hypothesized that this damage will have a negative impact on hip joint contact forces during activities of daily living (ADL). Methods 10 patients undergoing THA received an instrumented hip joint implant enabling real time in vivo measurements of hip joint loads using a direct lateral approach. Pre- and 3 months postoperative computed tomography (CT) scans were used for evaluation of the periarticular muscle status, using muscle volume, fat ratio and lean muscle volume as parameters. An analysis of in vivo hip contact forces was made 3 months after THA during ADL (walking, stair climbing, chair rising and sitting) and correlated with the morphology of the periarticular muscles. Results We found a significant decrease of volume by 25% (-3 to -45, p = 0.005) and increase in fat ratio of the Gluteus Minimus (Gmin), resulting in a decrease in lean muscle volume of 28% (-48 to 0, p = 0.008). This was accompanied by an inverse development in the Tensor Fasciae Latae (TFL) resulting in a lean muscle volume increase of 34% (-2 to -102, p = 0.013). Changes in Gluteus Medius (Gmed) and Gluteus Maximus (Gmax) have not been observed in the short-term follow up. A decreased Gmin lean muscle volume was found to strongly correlate with high in vivo joint contact forces in all tested ADL. Conclusion The decrease of Gmin volume can be seen as a direct effect of THA surgery, whereas the increase of TFL might compensate for loss of Gmin volume. Lean muscle volume and fat ratio were better predictors for joint contact forces than total muscle volume. These effects were most pronounced during sitting down and standing up due to the higher demand on the gluteal muscles during these activities.

Intact abductors of the hip play a crucial role in preventing limping and are known to be damaged through the direct lateral approach. The extent of trauma to the abductors after revision total hip replacement (THR) is unknown. The aim of this prospective study was to compare the pre- and post-operative status of the gluteus medius muscle after revision THR. We prospectively compared changes in the muscle and limping in 30 patients who were awaiting aseptic revision THR and 15 patients undergoing primary THR. The direct lateral approach as described by Hardinge was used for all patients. MRI scans of the gluteus medius and functional analyses were recorded pre-operatively and six months post-operatively. The overall mean fatty degeneration of the gluteus medius increased from 35.8% (1.1 to 98.8) pre-operatively to 41% (1.5 to 99.8) after multiple revision THRs (p = 0.03). There was a similar pattern after primary THR, but with considerably less muscle damage (p = 0.001), indicating progressive muscle damage. Despite an increased incidence of a positive Trendelenburg sign following revision surgery (p = 0.03) there was no relationship between the cumulative fatty degeneration in the gluteus medius and a positive Trendelenburg sign (p = 0.26). The changes associated with other surgical approaches to the hip warrant investigation. Cite this article: Bone Joint J 2014;96-B:1618–22.

Background Transcutaneous spinal direct current stimulation (tsDCS) is a new non-invasive technique to modulate spinal cord activity. The pathophysiological concept of primary RLS proposes increased spinal excitability. Objective This pilot study used tsDCS to reduce pathologically enhanced spinal excitability in RLS patients and to thereby ameliorate clinical symptoms. Methods 20 patients with idiopathic RLS and 14 healthy subjects participated in this double-blinded, placebo-controlled study. All participants received one session of cathodal, anodal and sham stimulation of the thoracic spinal cord for 15 min (2.5 mA) each, in randomized order during their symptomatic phase in the evening. The soleus Hoffmann-reflex with Hmax/Mmax-ratio and seven different H2/H1-ratios (of two H-reflex responses to double stimuli) were measured. The RLS symptoms were assessed by a visual analogue scale (VAS). All parameters were measured before and twice after tsDCS. Results RLS patients showed increased H2/H1-ratios during their symptomatic phase in the evening. Application of anodal stimulation led to a decreased H2/H1-ratio for 0.2 and 0.3 s interstimulus intervals in patients. Furthermore, application of anodal and cathodal stimulation led to a reduction in restless legs symptoms on the VAS, whereas application of sham stimulation had no effects on either the VAS or on the H2/H1-ratio in patients. VAS changes did not correlate with changes of H2/H1-ratios. Conclusions This is the first tsDCS study in idiopathic RLS, which resulted in short-lasting clinical improvement. Furthermore, our results support the pathophysiological concept of spinal cord hyperexcitability in primary RLS and provide the basis for a new non-pharmacological treatment tool.

Purpose: Recent DTI studies demonstrated the possibility of fiber geometry visualization in skeletal muscle. We tested for an association between muscle power and standard DTI parameters, e. g. fractional anisotropy. Materials and Methods: Maximal muscle power (Lmax) of the soleus muscle was determined in 11 healthy subjects. Subsequently DTI was performed and standard parameters (fractional anisotropy – FA, mean diffusivity – MD, parallel diffusivity – PD, radial diffusivity – RD) were extracted in an ROI of the soleus muscle. Results: We found a signficant association of Lmax with FA (neg. correlation: r = -0.85, p = 0.0015) and RD (pos. correlation r = 0.80, p = 0.047). There was no signficant association of MD or PD. Conclusion: Maximum muscle power is an indirect measure of fiber type distribution. The correlation between muscle power and DTI parameters can be explained by differences in fiber diameter and differences in the intracellular microstructure of type-1 and type-2 fibers. DTI should be evaluated as a tool for non-invasive quantification of fiber type distribution in skeletal muscle. Key Points: Citation Format

Choosing a surgical approach for total hip arthroplasty (THA) has a patient-specific impact on peri-operative muscle damage as well as postoperative functional outcome. Women and aged patients increasingly benefit from minimally invasive surgical procedures. For this reason, and due to the distinctly different bony anatomy of men and women, the hypothesis of this study is that muscle distribution around the hip joint is dependent on sex and age. The goal of this study was to analyse hip musculature in men and women and to correlate total muscle volume distribution.From 93 computed tomography (CT) scans of the pelvis (45 men, 48 women) volumes of gluteus medius (GMV), gluteus maximus (GXV) and tensor faciae latae (TFL) muscles were measured on both sides of the pelvis. The distribution of muscle volumes was normalised to patient weight and then correlated with sex and age.The measured muscle volumes featured no major differences between the left and the right side. The absolute total volume of the hip-encompassing muscular system (TMV) is bigger in men than in women. Correlations between TMV and collected data were observed in both sexes in relation to body weight and size (men p .00001; women p 0.001). With increased body weight, the TMV of the male patients increased progressively (women 11.2 cm TMV/kg KG vs. men 17.4 cm TMV/kg KG) (p 0.04). The relative distribution of each muscle volume (GMV, GXV, TFL) around the hip joint showed no major differences with respect to sex and/or age (p 0.986 and 0.996, respectively).The equal relative muscle distribution in men and women around the hip joint reflects neither sex-related differences observed in clinical outcomes after THA nor bony anatomy. Yet men exhibited more muscle reserves (muscle volume; absolute and in relation to body mass) , which could explain the better outcome in men after THA. Furthermore, this suggests the extraordinary importance of muscle-sparing surgical approaches in women. The results represent the rationale for designing and analysing future studies of sex-specific therapies with regard to hip-joint muscles.

The influence of surgical trauma on gluteus minimus muscle in total hip arthroplasty (THA) and the impact on functional outcome has been hardly investigated up to now. Potential risks of minimus damage during the approach or femoral preparation is due to its attachment to the anterior facet of the greater trochanter. Possible trauma-associated functional deficits of minimus muscle may result in reduced abduction force or in an unstable hip joint. The aim of the present study was to assess the pre- and post-operative gluteus minimus muscle (tendon defects and fatty atrophy) in patient with anterolateral minimally invasive and modified lateral approach by means of magnetic resonance imaging (MRI) and to investigate the associated impact on functional outcome.Thirty-eight patients [average age, 64 years (35-80); BMI, 28 kg/m(2) (19-35)] with primary coxarthrosis were prospectively enrolled in the study. A cementless hip prosthesis was implanted either via a minimally invasive anterolateral or a modified direct lateral approach. Patients were clinically and radiologically (MRI) examined preoperatively, 3, and 12 months postoperatively. Additionally, the Harris hip score, a pain score (NRS 0-10) and a satisfaction score (1-6) were recorded. To test the function of the abductor muscles the Trendelenburg's sign and the abductor muscle strength were evaluated. MRI evaluation includes the assessment of tendon defects and fatty atrophy of the minimus muscle.Tendon defects and fatty atrophy were seen in nearly 50% of the patients after THA. Harris hip-, pain-, and satisfaction scores did not correlate with the MR findings. There was also no impact on the abduction strength or the Trendelenburg's sign. Furthermore, the frequency of minimus damage was neither influenced by age, gender, BMI nor by the applied approach.Muscle atrophy and tendon defects of the minimus muscle appear frequently after THA without any favored relation to the lateral or anterolateral approach. The extent of injured minimus muscle has a minor impact on the clinical outcome particularly not on the abduction strength within the first postoperative year. The main function of the gluteus minimus is rather the centralization of the femoral head in the joint during the gait cycle than hip abduction and stabilization of the pelvis. The use of a straight stem with the associated need for lateral femoral preparation may be a risk factor for minimus tendon damage. Therefore, the surgeon should pay special attention to the prevention of surgical trauma to the gluteus minimus muscle during femoral preparation.

Introduction Interscalene and subacromial infusion of local anesthetics have both been shown to be effective in alleviating pain after shoulder arthroscopy. We performed a prospective randomized clinical trial in which both methods were compared in patients after acromioplasty. Methods Forty patients received a subacromial (n = 20) or an interscalene (n = 20) continuous infusion of 2% ropivacaine (2 mL/h) after arthroscopic acromioplasty. Visual analog scale pain scores, additional medication requirements, and side effects were evaluated for 43 hours. The incidence of night pain was recorded. Results Compared with the subacromial infusion, the continuous interscalene infusion of ropivacaine in the operated-on shoulder resulted in significantly reduced visual analog scale pain scores measured during rest, and also during exercise at 8 and 12 hours after surgery. The incidence of night pain was significantly lower in the interscalene group ( P = .018). Conclusion A continuous subacromial infusion of 0.2% ropivacaine (2 mL/h) is inferior to continuous interscalene infusion, particularly during the first 12 hours, but could be an alternative in patients with contraindications of interscalene anesthesia or when acromioplasty is performed as an outpatient procedure.

Apart from its hematopoietic effect, erythropoietin (EPO) is known as pleiotropic cytokine with anti-inflammatory and anti-apoptotic properties. Here, we evaluated for the first time the EPO-dependent regeneration capacity in an in vivo rat model of skeletal muscle trauma. A myoblast cell line was used to study the effect of EPO on serum deprivation-induced cell apoptosis in vitro. A crush injury was performed to the left soleus muscle in 80 rats treated with either EPO or saline. Muscle recovery was assessed by analysis of contraction capacities. Intravital microscopy, BrdU/laminin double immunohistochemistry and cleaved caspase-3 immunohistochemistry of muscle tissue on days 1, 7, 14, and 42 posttrauma served for assessment of local microcirculation, tissue integrity, and cell proliferation. Serum deprivation-induced myoblast apoptosis of 23.9 +/- 1.5% was reduced by EPO to 17.2 +/- 0.8%. Contraction force analysis in the EPO-treated animals revealed significantly improved muscle strength with 10-20% higher values of twitch and tetanic forces over the 42-day observation period. EPO-treated muscle tissue displayed improved functional capillary density as well as reduced leukocytic response and consecutively macromolecular leakage over day 14. Concomitantly, muscle histology showed significantly increased numbers of BrdU-positive satellite cells and interstitial cells as well as slightly lower counts of cleaved caspase-3-positive interstitial cells. EPO results in faster and better regeneration of skeletal muscle tissue after severe trauma and goes along with improved microcirculation. Thus, EPO, a compound established as clinically safe, may represent a promising therapeutic option to optimize the posttraumatic course of muscle tissue healing.

Background The aim of this study was to assess the diagnostic performance of synovial aspiration in Girdlestone hips, without a Polymethylmethacrylate (PMMA) spacer, for the detection of infection persistence before total hip arthroplasty (THA) reimplantation. Methods Seventy-four patients undergoing stage revision THA surgery were included in this retrospective cohort study. Both synovial cultures and serum C-reactive protein values were acquired before explantation of the THA and of the Girdlestone hip before reimplantation. Results The diagnostic performance of the synovial aspiration of the Girdlestone hip achieved a sensitivity of only 13% and a specificity of 98%. The determination of the serum C-reactive protein value for Girdlestone hips achieved a sensitivity of 95% and a specificity of only 20%. Conclusions Our data show that the Girdlestone aspiration can neither reliably confirm nor exclude a persistence of infection.

Fiber type distribution within a skeletal muscle, i.e. the quantification of the relative amount of type 1 (slow-twitching) and type 2 (fast-twitching) muscle fibers, is of great interest for the monitoring of the effects of training or the treatment of muscle diseases. The purpose of this study was to determine the feasibility of diffusion tensor imaging (DTI) as a tool for noninvasive fiber type quantification in human skeletal muscle. The right calves of 12 healthy volunteers were examined using DTI at 1.5 T. Standard DTI parameters, including fractional anisotropy (FA), and mean, radial and parallel diffusivity (MD, RD and PD, respectively), were determined in the soleus muscle. Fiber type proportion and mean fiber diameter within the soleus muscle were quantified from tissue specimens obtained via a fine needle biopsy. Linear regression analysis tested for associations between DTI and biopsy results. FA values were correlated significantly with fiber type proportion, such that higher FA values indicated a higher proportion of type 1 fibers (R(2) = 0.5, p = 0.01). This was based on lower diffusivity perpendicular to the main axis of the fiber in subjects with a higher type 1 fiber proportion (RD: R(2) = 0.52, p = 0.008). MD was also correlated with the proportion of type 1 fibers (R(2) = 0.37, p = 0.037), whereas PD showed no significant correlation. DTI is a promising method for the noninvasive estimation of fiber type proportion in skeletal muscle. This technique may be used to monitor training effects or may be further developed as a biomarker in certain muscle diseases.

Background Mesenchymal stem cell (MSC) therapy has the potential to enhance muscular regeneration. In previous publications, our group was able to show a dose-response relationship in female animals between the amount of transplanted cells and muscle force. The impact of sex on the regeneration of musculoskeletal injuries following MSC transplantation remains unclear. Objective We investigated histologic and biomechanical regeneration parameters in rats after autologous transplantation of MSCs. Our hypothesis was that female rats have greater muscle regeneration potential than male rats after autologous MSC transplantation. Methods Thirty-six Sprague-Dawley rats received an open crush trauma of the left soleus muscle. One week after trauma, 2.5 × 10 6 autologous MSCs, harvested from tibial biopsies, were transplanted locally (female, n = 9; male, n = 9). Control animals received saline solution (female, n = 9; male, n = 9). Histologic analysis and biomechanical evaluation by in vivo muscle force measurement were performed 3 weeks after transplantation. Results MSC therapy improved the force of the injured soleus in male rats significantly (twitch: treated, 0.76 [0.51–1.15]; twitch: untreated, 0.45 [0.32–0.73] [ P = 0.01]; tetany: treated, 0.63 [0.4–1.21], tetany: untreated, 0.34 [0.16–0.48] [ P = 0.04]). Force measurements in females also revealed significant improvements (twitch: treated, 0.71 [0.38–0.96]; twitch: untreated, 0.36 [0.18–0.63] [ P = 0.005]; tetany: treated, 0.53 [0.21–0.68]; tetany: untreated, 0.27 [0.11–0.47] [ P = 0.01]). The intersexual comparison of fast twitch and tetanic contraction forces revealed no significance (twitch, P = 0.55; tetany, P = 0.19). The histologic analysis showed no differences in the amount of fibrotic tissue (male, P = 0.9; female, P = 0.14) and the size of muscle area (male, P = 0.2; female, P = 0.56) following treatment. Male animals showed higher values for muscle area ( P = 0.011) and less fibrosis ( P = 0.028), independent of treatment. Conclusion The outcome of skeletal muscle regeneration after injury can be improved in animals of both sexes with MSC transplantation.

Clinical findings and blood parameters often are inconclusive in patients with periprosthetic joint infections. Among the accepted criteria for diagnosis, histologic analysis of debrided tissue can detect infection in most cases but does not allow intraoperative decision making. We evaluated the validity of intraoperative frozen sections for detection of prosthetic infections. The results from frozen and permanent sections of periprosthetic membranes of 64 consecutive patients who underwent exchange procedures after hip arthroplasty were compared using the histopathologic consensus classification of Morawietz et al. Blood parameters (erythrocyte sedimentation rate, leukocyte count, C-reactive protein) and culture results of preoperatively aspirated joint fluid and intraoperative tissue samples were correlated with the histologic results. In 50 patients (78.1%), agreement was found between the frozen and permanent sections. Two patients (3.1%) revealed a discrepancy between the two histologic methods. In 12 patients (18.8%), a diagnosis was not possible based on the frozen sections because the tissue samples were not representative enough for definite classification. For the analyzable cases (n = 52), the sensitivity of frozen-section histologic analysis was 86.6%, specificity 100%, and accuracy 96.2%. Our data support a recommendation for use of intraoperative frozen sections for diagnosis of septic versus aseptic loosening in revision hip surgery. Level of Evidence: Level II, diagnostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Background context Computed tomography (CT) represents the state of the art for the postoperative verification of the implant position after transpedicular stabilizations. Magnetic resonance imaging (MRI) has not challenged the CT, yet, because of susceptibility artifacts but would be favorable as a diagnostic tool for its excellent soft-tissue qualities. Purpose A study that analyzed if an artifact-reduced MRI could overcome this problem and provide sufficient data for the postoperative assessment was conducted. Study design The study design was a radiologic comparison of CT and MRI techniques evaluating pedicle screw placement after spinal fusion. Patient sample Fifty consecutive patients were given an MRI and a CT after a transpedicular stabilization surgery. Thirty-eight patients suffered from degenerative spinal disorders; three surgeries had become necessary because of spondylodiscitis, eight patients suffered from metastatic vertebrae destruction, and one patient experienced a fracture. Outcome measures Any contact of a malpositioned pedicle screw with the dura and/or radicular structures was identified as an implant-associated complication and was compared with postoperative clinical patient findings. Methods In total, 338 pedicular screws were analyzed in regard to their intrapedicular position. The double-blind evaluation of MRI and CT data was carried out by two radiologists and two spine surgeons. Accuracy of the CT analysis was calculated based on the interobserver agreement of 100%. Magnetic resonance imaging accuracy was calculated. Results The interobserver accuracy of the CT data amounted to a median of 89.8% and in the MRI data of 86.7%. Intraobserver comparisons showed a significant difference between CT and magnetic resonance evaluations in one observer (κ=0.293). In all other observers, the results were concordant with kappa values from κ=0.328 to κ=0.702. There was a high degree of agreement regarding the diagnosis of malpositioned pedicle screw and corresponding clinical symptoms between both techniques. Conclusions The presented data show that artifact-reduced MRI is equivalent to CT imaging in the postoperative evaluation of titanium spinal rod-screw systems. We therefore conclude that MRI should be considered as an alternative tool for the golden standard CT for postoperative imaging controls for its advantages in soft-tissue analysis.

Autologous mesenchymal stem cells (MSCs) have been shown to improve the functional outcome after skeletal muscle trauma. The mechanisms behind this improvement have to be answered prior to a future clinical application. We investigated for the first time the in vivo distribution and behavior of MSCs after local transplantation into a severely injured muscle with magnetic resonance imaging (MRI). Autologous rat MSCs were labeled with very small iron oxide nanoparticles (VSOPs) and transplanted into the soleus muscle 1 week after an open crush injury. Distribution and migration of the cells were evaluated in vivo over time by the repeated performance of high-resolution MRI at 7 T. Three and 6 weeks after transplantation, the muscles were histologically analyzed. The labeled MSCs could be visualized inside the traumatized muscles 24 h after transplantation showing characteristic signal reductions in T2*-weighted sequences. The hypointense signal could be followed over 6 weeks and could be easily discriminated from the structures of the injured muscle. The cell pools did not migrate inside the muscle and showed a decrease in volume over time. Prussian blue-stained histologic sections showed a topographical correlation of the respective MRI signal and nanoparticle-labeled cells. Fusion events of marked cells with regenerating myofibers could be observed. The presented study demonstrates for the first time the feasibility of an in vivo tracking of MSCs with MRI after a severe skeletal muscle injury. The investigated method can be a powerful tool both in experimental setups and in possible clinical applications of stem cell-supported skeletal muscle regeneration.

Insufficient post-traumatic skeletal muscle regeneration with consecutive functional deficiency continues to be a serious problem in orthopedic and trauma surgery. Transplantation of autologous muscle precursor cells has shown encouraging results in muscle trauma treatment but is associated with significant donor site morbidity. In contrast to this, bone marrow-derived (BMD) cells can be obtained without any functional deficit by puncture. The goal of this study was to examine whether regular muscle regeneration can be improved by local application of autologous BMD cells in a rat model of blunt skeletal muscle trauma. One week after standardized open blunt crush injury to the left soleus muscle, 10(6) autologous BMD cells were injected into the traumatized muscle of male Sprague Dawley rats. Rats of the control group received saline solution as treatment. Three weeks after application, the fast twitch and tetanic contraction capacity of the soleus muscles was measured bilaterally by stimulating the sciatic nerves. Contraction forces of injured soleus muscles in control animals recovered to 39 +/- 10% (tetanic) and 59 +/- 12% (fast twitch) of the contralateral noninjured soleus muscles (p < 0.001). In contrast, autologous BMD cell injection significantly restored contractile forces to 53 +/- 8% (tetanic) and 72 +/- 13% (fast twitch) compared to those observed in contralateral noninjured soleus muscles. Thus, muscle function was significantly increased by BMD cell treatment (tetanic, p = 0.014; fast twitch, p = 0.05). In conclusion, autologous BMD cell grafting leads to an increase in contraction force, 14% in tetanic and 13% in fast twitch stimulation, demonstrating its potential to improve functional outcome after skeletal muscle crush injury.

Background Neurofibromatosis type 1 (NF1) is one of the most common genetic disorders causing learning disabilities by mutations in the neurofibromin gene, an important inhibitor of the RAS pathway. In a mouse model of NF1, a loss of function mutation of the neurofibromin gene resulted in increased gamma aminobutyric acid (GABA)-mediated inhibition which led to decreased synaptic plasticity and deficits in attentional performance. Most importantly, these defictis were normalized by lovastatin. This placebo-controlled, double blind, randomized study aimed to investigate synaptic plasticity and cognition in humans with NF1 and tried to answer the question whether potential deficits may be rescued by lovastatin. Methods In NF1 patients (n = 11; 19–44 years) and healthy controls (HC; n = 11; 19–31 years) paired pulse transcranial magnetic stimulation (TMS) was used to study intracortical inhibition (paired pulse) and synaptic plasticity (paired associative stimulation). On behavioural level the Test of Attentional Performance (TAP) was used. To study the effect of 200 mg lovastatin for 4 days on all these parameters, a placebo-controlled, double blind, randomized trial was performed. Results In patients with NF1, lovastatin revealed significant decrease of intracortical inhibition, significant increase of synaptic plasticity as well as significant increase of phasic alertness. Compared to HC, patients with NF1 exposed increased intracortical inhibition, impaired synaptic plasticity and deficits in phasic alertness. Conclusions This study demonstrates, for the first time, a link between a pathological RAS pathway activity, intracortical inhibition and impaired synaptic plasticity and its rescue by lovastatin in humans. Our findings revealed mechanisms of attention disorders in humans with NF1 and support the idea of a potential clinical benefit of lovastatin as a therapeutic option.

Background No regenerative approach has thus far been shown to be effective in skeletal muscle injuries, despite their high frequency and associated functional deficits. We sought to address surgical trauma‐related muscle injuries using local intraoperative application of allogeneic placenta‐derived, mesenchymal‐like adherent cells (PLX‐PAD), using hip arthroplasty as a standardized injury model, because of the high regenerative and immunomodulatory potency of this cell type. Methods Our pilot phase I/IIa study was prospective, randomized, double blind, and placebo‐controlled. Twenty patients undergoing hip arthroplasty via a direct lateral approach received an injection of 3.0 × 108 (300 M, n = 6) or 1.5 × 108 (150 M, n = 7) PLX‐PAD or a placebo (n = 7) into the injured gluteus medius muscles. Results We did not observe any relevant PLX‐PAD‐related adverse events at the 2‐year follow‐up. Improved gluteus medius strength was noted as early as Week 6 in the treatment‐groups. Surprisingly, until Week 26, the low‐dose group outperformed the high‐dose group and reached significantly improved strength compared with placebo [150 M vs. placebo: P = 0.007 (baseline adjusted; 95% confidence interval 7.6, 43.9); preoperative baseline values mean ± SE: placebo: 24.4 ± 6.7 Nm, 150 M: 27.3 ± 5.6 Nm], mirrored by an increase in muscle volume [150 M vs. placebo: P = 0.004 (baseline adjusted; 95% confidence interval 6.0, 30.0); preoperative baseline values GM volume: placebo: 211.9 ± 15.3 cm3, 150 M: 237.4 ± 27.2 cm3]. Histology indicated accelerated healing after cell therapy. Biomarker studies revealed that low‐dose treatment reduced the surgery‐related immunological stress reaction more than high‐dose treatment (exemplarily: CD16+ NK cells: Day 1 P = 0.06 vs. placebo, P = 0.07 vs. 150 M; CD4+ T‐cells: Day 1 P = 0.04 vs. placebo, P = 0.08 vs. 150 M). Signs of late‐onset immune reactivity after high‐dose treatment corresponded to reduced functional improvement. Conclusions Allogeneic PLX‐PAD therapy improved strength and volume of injured skeletal muscle with a reasonable safety profile. Outcomes could be positively correlated with the modulation of early postoperative stress‐related immunological reactions.