The Influence of Multilevel Spinal Deformity Surgery on the EuroQol 5 Dimensions' (EQ-5D) Questionnaire and Residential Status in the Elderly: A Prospective, Observational, Multicenter Study.

STUDY DESIGN: Multicenter, international prospective study. OBJECTIVE: This study investigated the clinical outcome up to 2 years after multi-level spinal deformity surgery in the elderly by reporting the minimal clinically important difference (MCID) of EuroQol 5-dimensions (EQ-5D), EQ-VAS, and residential status. METHODS: As an ancillary study of 219 patients ≥60 years with spinal deformity undergoing primary instrumented fusion surgery of ≥5 levels, this study focuses on EQ-5D (3-L) as the primary outcome and EQ-VAS and residential status as secondary outcomes. Data on EQ-5D were compared between pre-operatively and postoperatively at 10 weeks, 12 months, and 24 months. An anchor-based approach was used to calculate the MCID. RESULTS: The EQ-5D index and EQ-VAS, respectively, improved significantly at each time point compared to pre-operatively (from .53 (SD .21) and 55.6 (SD 23.0) pre-operatively to .64 (SD .18) and 65.8 (SD 18.7) at 10 weeks, .74 (SD .18) and 72.7 (SD 18.1) at 12 months, and .73 (SD .20) and 70.4 (SD 20.4) at 24 months). 217 (99.1%) patients lived at home pre-operatively, while 186 (88.6%), 184 (98.4%), and 172 (100%) did so at 10 weeks, 12 months, and 24 months, respectively. Our calculated MCID for the EQ-5D index at 1 year was .22 (95% CI .15-.29). CONCLUSIONS: The EQ-5D index significantly increased at each time point over 24 months after ≥5 level spinal deformity surgery in elderly patients. The MCID of the EQ-5D-3 L was .22. Patients living at home pre-operatively can expect to be able to live at home 2 years postoperatively.

Influence of Spine Curvature on the Efficacy of Transcutaneous Lumbar Spinal Cord Stimulation.

Transcutaneous spinal cord stimulation is a non-invasive method for neuromodulation of sensorimotor function. Its main mechanism of action results from the activation of afferent fibers in the posterior roots-the same structures as targeted by epidural stimulation. Here, we investigated the influence of sagittal spine alignment on the capacity of the surface-electrode-based stimulation to activate these neural structures. We evaluated electromyographic responses evoked in the lower limbs of ten healthy individuals during extension, flexion, and neutral alignment of the thoracolumbar spine. To control for position-specific effects, stimulation in these spine alignment conditions was performed in four different body positions. In comparison to neutral and extended spine alignment, flexion of the spine resulted in a strong reduction of the response amplitudes. There was no such effect on tibial-nerve evoked H reflexes. Further, there was a reduction of post-activation depression of the responses to transcutaneous spinal cord stimulation evoked in spinal flexion. Thus, afferent fibers were reliably activated with neutral and extended spine alignment. Spinal flexion, however, reduced the capacity of the stimulation to activate afferent fibers and led to the co-activation of motor fibers in the anterior roots. This change of action was due to biophysical rather than neurophysiological influences. We recommend applying transcutaneous spinal cord stimulation in body positions that allow individuals to maintain a neutral or extended spine.

Stratifying outcome based on the Oswestry Disability Index for operative treatment of adult spinal deformity on patients 60 years of age or older: a multicenter, multi-continental study on Prospective Evaluation of Elderly Deformity Surgery (PEEDS).

BACKGROUND CONTEXT: Patients with adult spinal deformity suffer from disease related disability as measured by the Oswestry Disability Index (ODI) for which surgery can result in significant improvements. PURPOSE: The purpose of this study was to show the change in overall and individual components of the ODI in patients aged 60 years or older following multi-level spinal deformity surgery. STUDY DESIGN: Prospective, multicenter, multi-continental, observational longitudinal cohort study PATIENT SAMPLE: Patients ≥60 years undergoing primary spinal fusion surgery of ≥5 levels for coronal, sagittal or combined deformity. OUTCOME MEASURES: Oswestry Disability Index (ODI) METHODS: : Patients completed the ODI pre-operatively for baseline, then at 10 weeks, 12 months and 24 months post-operatively. ODI scores were grouped into deciles, and change was calculated with numerical score and improvement or worsening was further categorized from baseline as substantial (≥20%), marginal (≥10-<20%) or no change (within 10%). RESULTS: Two-hundred nineteen patients met inclusion criteria for the study. The median number of spinal levels fused was 9 [Q1=5.0, Q3=12.0]. Two-year mean (95% CI) ODI improvement was 19.3% (16.7%; 21.9%; p<.001) for all age groups, with mean scores improved from a baseline of 46.3% (44.1%; 48.4%) to 41.1% (38.5%; 43.6%) at 10 weeks (p<.001), 28.1% (25.6%; 30.6%) at 12 months (p<.001), and 27.0% (24.4%; 29.5%) at 24 months (p<.001). At 2 years, 45.5% of patients showed 20% or greater improvement in ODI, 23.7% improved between 10% and 20%, 26.3% reported no change (defined as±10% from baseline), 4.5% of patients reported a worsening between 10% to 20%, and none reported worsening greater than 20%. 59.0% of patients were severely disabled (ODI >40%) pre-operatively, which decreased to 20.2% at 2 years. Significant improvement was observed across all 10 ODI items at 12 and 24 months. The largest improvements were seen in pain, walking, standing, sex life, social life and traveling. CONCLUSIONS: In this prospective, multicenter, multi-continental study of patients 60 years or older undergoing multi-level spinal deformity surgery, almost 70% of patients reported significant improvements in ODI without taking into account surgical indications, techniques or complications. Clear data is presented demonstrating the particular change from baseline for each decile of pre-operative ODI score, for each sub-score, and for each age group.

Primary sarcomas of the spine: population-based demographic and survival data in 107 spinal sarcomas over a 23-year period in Ontario, Canada.

BACKGROUND CONTEXT: Spinal sarcomas are a rare, heterogeneous group of mesenchymal tumors. Current literature reporting demographic variables and survival information is limited to small case series, and a single registry with variable treatment modalities and time periods. PURPOSE: We report on population-level data regarding all spinal sarcomas diagnosed over a 23-year period in Ontario, Canada, for the purposes of calculating incidence and prevalence of these tumors. Secondarily, survival is assessed by tumor type as well as adjuvant therapies during this time period. STUDY DESIGN: Retrospective Cohort Study PATIENT SAMPLE: Population-based data from the Institute for Clinical Evaluative Sciences (ICES) between 1993 and 2015. OUTCOME MEASURES: Outcome measures include incidence and prevalence of spinal osteosarcoma, Ewing's sarcoma, and chondrosarcoma of the spine, as well as 2-, 5-, 10- and 15-year survival and prevalence of adjuvant therapies. METHODS: Utilizing population-based data from the Institute for Clinical Evaluative Sciences (ICES) between 1993 and 2015, ICD codes were searched and available data extracted for the purposes of reporting basic demographic information and calculation of Kaplan Meyer survival curves. Databases include the Ontario Cancer Registry, Discharge Abstract Database, Ontario Health Insurance Plan, National Ambulatory Care Reporting System, Registered Persons DataBase (death) were analyzed. RESULTS: One hundred and seven spinal sarcomas were identified, with a mean incidence was 0.38 sarcomas per million population per year, that was stable over time. The mean prevalence was 8.1 sarcomas per million population. The most common diagnosis was Ewing's sarcoma (48 [44.9%] patients), followed by chondrosarcoma (33 [30.8%] patients), and osteosarcoma (26 [24.3%] patients). Chondrosarcoma had the highest survival rates with 77.2% and 64.2% 5- and 10-year survival rates, respectively, followed by Ewing's sarcoma with 48.1% and 44.9% 5 and 10-year survival and osteosarcoma with 36.0% and 30.9% 5- and 10-year survival. CONCLUSIONS: Spinal sarcoma is a rare disease with variable survival depending on the histologic diagnosis. This population-level study involves a heterogeneous group of patients with variable stages of disease at presentation and variable treatments. Our data fit with the published literature for survival for those treated conservatively and surgically. Our data show considerable improvement in 5- and 10-year mortality when compared with previous population level studies on earlier patient cohorts, likely reflecting improvements in systemic and surgical treatments.

Shoulder Muscle Strength and Neuromuscular Activation 2 Years after Reverse Shoulder Prosthesis-An Experimental Case Control Study.

Although reverse shoulder arthroplasty (RSA) has shown successful postoperative outcomes, little is known about compensatory activation patterns of remaining shoulder muscles following RSA. The purpose of this experimental case control series was to investigate shoulder muscle strength and neuromuscular activation of deltoid and teres minor muscles 2 years after RSA. Humerus lengthening, center-of-rotation medialization, maximal voluntary strength, and electromyographic (EMG) activity were compared between the operated and the non-operated side of 13 patients (mean age: 73 years). Shoulder muscle strength was significantly lower on the operated side for external rotation (-54%), internal rotation (-20%), and adduction (-13%). Agonist deltoid EMG activity was lower on the operated side for shoulder flexion, extension, and internal and external rotation (p < 0.05). Antagonist deltoid coactivation was higher on the operated side for external rotation (p < 0.001). Large correlation coefficients were observed between shoulder adductor strength asymmetry and both center-of-rotation medialization (r = -0.73) and humerus lengthening (r = 0.71). Shoulder abduction strength and neuromuscular activation were well preserved 2 years after RSA, while persistent strength and activation deficits were observed for shoulder adduction and internal and external rotation. Additional studies are required to elucidate shoulder neuromuscular activation patterns before and after RSA to support decision making for surgical, implant design, and rehabilitation choices.

C1-C2 posterior screw fixation in atlantoaxial fractures revisited: technical update based on 127 cases.

INTRODUCTION: Posterior fusion of traumatic odontoid fractures by C1 lateral mass and C2 isthmic screws (modified Harms-Goel technique) is a viable alternative to transarticular screw fixation due to its universal applicability. This retrospective study reports on a series of 127 patients. MATERIAL AND METHODS: Our clinical database was screened for patients with fractures of the upper cervical spine incorporating a C2 fracture, operated on between 2007 and 2015. Patients were included if fused by internal fixation via C1 lateral mass screws, C2 isthmic screws in freehand technique under lateral fluoroscopy. Screw placement was controlled postoperatively by computed tomography and rated using the Gertzbein & Robbins classification. Surgery-related complications, consecutive treatment, revision surgeries and duration of surgeries were registered. RESULTS: In total, 127 patients were identified with altogether 572 screws. Correct screw positions of grade A and B according to Gertzbein & Robbins were achieved in a total of 539 (94.2%) screws (grade A: 453 (79.2%); grade B: 86 (15%)), grade C screw malpositions noted in 21 (3.7%), grade D in 10 (1.7%) and grade E in 2 (0.3%) screws. Vertebral artery canal breaches occurred in 29 screws (5.1%), with vertebral artery occlusion in 4 patients. Coiling of injured vertebral artery had to be performed in one patient. None of these patients suffered clinically apparent cerebrovascular complications. Revision surgery was performed in 8 patients (6%). CONCLUSION: Posterior fixation of atlantoaxial fractures by C1 lateral mass and C2 isthmic screws with fluoroscopy without navigation is a safe and feasible method but not free of risk of vertebral artery injuries. These slides can be retrieved under Electronic Supplementary Material.

Treatment considerations for cervical and cervicothoracic spondylodiscitis associated with esophageal fistula due to cancer history or accidental injury: a 9-patient case series.

BACKGROUND: The combination of cervical spondylodiscitis and esophageal fistula is rare but life-threatening. Due to both the rarity of these conditions' coincidence and the complexity and heterogeneity of individual cases, there is no optimal treatment or management approach. The aims of this study are to obtain an overview of patients' outcomes and to discuss treatment options. METHOD: This study is a retrospective analysis of patients who presented with cervical spondylodiscitis and associated esophageal fistula between January 2010 and November 2018. We examined reports of 59 patients who suffered from cervical spondylodiscitis and included nine patients (15.25%) who had an esophageal fistula as the underlying cause. We assessed clinical findings, treatment, and outcome. RESULTS: Three of the nine patients were female, and the mean age of the sample was 64.56 years. Six of the patients had a history of esophagopharyngeal cancer and had undergone tumor resection followed by radiotherapy. Two of the remaining patients' fistulas were caused by an iatrogenic injury during cervical spine surgery and a swallowed toothpick; in the final case, the origin remained unclear. Five patients presented with tetraparesis or tetraplegia, and the other four patients were neurologically intact. In seven cases, dorsal instrumentation was initially performed. Three patients secondarily received a ventral approach for debridement, and one received explantation of the ventral implants. Two patients died during the hospital stay, and three were transferred to a palliative care unit. Thus, the spondylodiscitis and esophageal fistula were cured in only four patients. At discharge, two patients were neurologically intact, two others remained in tetraparesis. CONCLUSIONS: Cervical spondylodiscitis in association with an esophageal fistula carries high morbidity and high mortality. Because patients whose infections are not cured have high morbidity, we recommend using interdisciplinary and individual management, including definite surgical treatment of the discitis and fistula, in every case.

Improved prediction of incident vertebral fractures using opportunistic QCT compared to DXA.

OBJECTIVES: To compare opportunistic quantitative CT (QCT) with dual energy X-ray absorptiometry (DXA) in their ability to predict incident vertebral fractures. METHODS: We included 84 patients aged 50 years and older, who had routine CT including the lumbar spine and DXA within a 12-month period (baseline) as well as follow-up imaging after at least 12 months or who sustained an incident vertebral fracture documented earlier. Patients with bone disorders aside from osteoporosis were excluded. Fracture status and trabecular bone mineral density (BMD) were retrospectively evaluated in baseline CT and fracture status was reassessed at follow-up. BMDQCT was assessed by opportunistic QCT with asynchronous calibration of multiple MDCT scanners. RESULTS: Sixteen patients had incident vertebral fractures showing lower mean BMDQCT than patients without fracture (p = 0.001). For the risk of incident vertebral fractures, the hazard ratio increased per SD in BMDQCT (4.07; 95% CI, 1.98-8.38), as well as after adjusting for age, sex, and prevalent fractures (2.54; 95% CI, 1.09-5.90). For DXA, a statistically significant increase in relative hazard per SD decrease in T-score was only observed after age and sex adjustment (1.57; 95% CI, 1.04-2.38). The predictability of incident vertebral fractures was good by BMDQCT (AUC = 0.76; 95% CI, 0.64-0.89) and non-significant by T-scores. Asynchronously calibrated CT scanners showed good long-term stability (linear drift ranging from - 0.55 to - 2.29 HU per year). CONCLUSIONS: Opportunistic screening of mainly neurosurgical and oncologic patients in CT performed for indications other than densitometry allows for better risk assessment of imminent vertebral fractures than dedicated DXA. KEY POINTS: • Opportunistic QCT predicts osteoporotic vertebral fractures better than DXA reference standard in mainly neurosurgical and oncologic patients. • More than every second patient (56%) with an incident vertebral fracture was misdiagnosed not having osteoporosis according to DXA. • Standard ACR QCT-cutoff values for osteoporosis (< 80 mg/cm 3 ) and osteopenia (≤ 120 mg/cm 3 ) can also be applied scanner independently in calibrated opportunistic QCT.

Reoperation rates and risk factors for revision 4 years after dynamic stabilization of the lumbar spine.

BACKGROUND CONTEXT: The concept of dynamic stabilization (DS) of the lumbar spine for treatment of degenerative instability has been introduced almost two decades ago. Dynamic stabilization follows the principle of controlling movement in the coronal plane by providing load transfer of the spinal segment without fusion and, at the same time, reducing side effects such as adjacent segment disease (ASD). So far, only little is known about revision rates after DS due to ASD and screw loosening (SL). PURPOSE: The present study aimed to evaluate the longitudinal revision rates following dynamic pedicle screw stabilization in the lumbar spine and to determine specific risk factors predictive for ASD, SL, and overall reoperation in a large cohort with considerable follow-up. DESIGN: We carried out a post hoc analysis of a prospectively collected database in a level I spine center. PATIENTS EXAMPLE: The patient sample comprised 283 (151 female/132 male) consecutive patients suffering from painful degenerative lumbar segmental instability with or without spinal stenosis who underwent DS of the lumbar spine (Ulrich Cosmic, Ulrich Medical, Ulm, Germany) between January 2008 and December 2011. OUTCOME MEASURES: Longitudinal reoperation rate and risk factors predictive for revision surgery were evaluated. METHODS: We analyzed the longitudinal reoperation rate due to ASD and SL and overall reoperation. Risk factors such as age, gender, body mass index, lumbar lordosis (LL), number of segments, and number of previous surgeries were taken into account. Regular and mixed model logistic regressions were performed to determine risk factors for revision surgery on a patient and on a screw level. RESULTS: The mean age was 65.7±10.2 years (range 31-88). One hundred thirty-two patients were stabilized in 1 segment, 134 in 2 segments, 15 in 3 segments, and 2 patients in 4 segments. Reoperation rate for ASD and SL after 1 year was 7.4 %, after 2 years was 15.0%, and after a mean follow-up of 51.4±15 months was 22.6%. Reasons for revision were SL in 19 cases (6.6%), ASD in 39 cases (13.7%), SL and ASD in 6 cases, hematoma in 2 cases (0.7%), cerebrospinal fluid fistulae in 3 cases (1.1%), infection in 6 cases (2.1%), and implant failure in 1 case (0.4%). The patients' age, the number of stabilized segments, and the number of previous surgeries and postoperative LL had a significant influence on the probability for revision surgery. CONCLUSIONS: Reoperation rates after DS of the lumbar spine are comparable with rigid fixations. The younger the patient and the more segments are involved, the lower the LL and the more previous surgeries were found, the higher was the risk of revision. Risk of revision was almost twice as high in men compared with women. We therefore conclude that for clear clinical indication and careful evaluation of preoperative imaging data, DS using the Cosmic system seems to be a possible option. The presented data will help to further tailor indication and patient selection.

Robotic ultrasound-guided facet joint insertion.

PURPOSE: Facet joint insertion is a common treatment of chronic pain in the back and spine. This procedure is often performed under fluoroscopic guidance, where the staff's repetitive radiation exposure remains an unsolved problem. Robotic ultrasound (rUS) has the potential to reduce or even eliminate the use of radiation by using ultrasound with a robotic-guided needle insertion. This work presents first clinical data of rUS-based needle insertions extending previous work of our group. METHODS: Our system implements an automatic US acquisition protocol combined with a calibrated needle targeting system. This approach assists the physician by positioning the needle holder on a trajectory selected in a 3D US volume of the spine. RESULTS: By the time of submission, nine facets were treated with our approach as first data from an ongoing clinical study. The insertion success rate was shown to be comparable to current clinical practice. Furthermore, US imaging offers additional anatomical context for needle trajectory planning. CONCLUSION: This work shows first clinical data for robotic ultrasound-assisted facet joint insertion as a promising solution that can easily be incorporated into the clinical workflow. Presented results show the clinical value of such a system.

Revision Rate of Misplaced Pedicle Screws of the Thoracolumbar Spine-Comparison of Three-Dimensional Fluoroscopy Navigation with Freehand Placement: A Systematic Analysis and Review of the Literature.

BACKGROUND: Recent studies have shown higher accuracy rates of image-guided pedicle screw placement compared to freehand (FH) placement. However, data focusing on the impact of spinal navigation on the rate of revision surgeries caused by misplaced pedicle screws (PS) are scarce. OBJECTIVE: This study is aimed at identifying the rate of revision surgeries for misplaced PS comparing three-dimensional (3D) fluoroscopy navigation (3DFL) with FH PS placement. METHODS: A retrospective analysis was conducted of 2232 patients (mean age, 65.3 ± 13.5 years) with 13,703 implanted PS who underwent instrumentation of the thoracolumbar spine between 2007 and 2015. Group 1 received surgery with use of 3DFL (January 2011 to December 2015), group 2 received surgery in the FH technique (April 2007 to December 2015). Because the use of 3DFL was initiated in January 2011, the examined period for 3DFL-navigated surgeries is shorter. Patients routinely received postoperative computed tomography scans and/or intraoperative control 3D scans. RESULTS: There was an overall rate of revision surgeries for malpositioned PS of 2.9%. In the 3DFL group, the rate of secondary revision surgeries was significantly lower with 1.35% (15/1112 patients) compared to 4.38% (49/1120 patients) in the FH group, respectively (odds ratio, 3.35; P < 0.01). Of all PS in the 3DFL group (30/7548 PS), 0.40% needed revision surgery (P < 0.01) compared to 1.14% in the FH group (70/6155 PS). CONCLUSIONS: We were able to show that the use of 3DFL-navigated PS placement significantly reduces the rate of revision surgeries after posterior spinal instrumentation compared to freehand PS placement.

Osteoporosis Is the Most Important Risk Factor for Odontoid Fractures in the Elderly.

Traumatic odontoid fractures (TOFs) have been described as the most common injury affecting the C-spine in the elderly. Previous studies have identified degenerative changes and bone loss as important predisposing factors. However, their interaction and respective age-adjusted impact needs further clarification. We conducted a retrospective analysis of 5303 patients (aged ≥60 years) admitted to a level I trauma center between January 2008 and January 2016 who underwent CT imaging of the C-spine. Ninety-two patients with TOF and 80 patients with other cervical spine fractures (OCSF) were identified and a respective 3:1 age- and sex-matched control group without fractures after trauma was built. In all groups, cervical bone mineral density (cBMD) was determined using phantom calibration, and degenerative changes were evaluated in a qualitative manner. In all groups, the severity of degenerative changes of the C-spine increased with age (all p < 0.05) and was inversely correlated with cBMD (all p < 0.05). cBMD was the only significant predictor of a TOF in a multivariate logistic regression model (adjusted odds ratio [OR] = 3.066, 95% confidence interval [CI] 1.432-6.563 for cervical osteoporosis). An association between odontoid cysts and TOF reached significance only in Anderson and D'Alonzo (A&D) type II TOFs (aOR = 1.383; 95% CI 1.012-1.890). Patients with OCSFs, compared with patients with TOFs, were younger (median 74 versus 83 years) and had a higher cBMD (median 208 mg/mL versus 172 mg/mL). No differences were observable when comparing cBMD and grades of degenerative changes between OCSFs and their control group (all p >0.1). Decreased cBMD is the major predisposing factor for the occurrence of TOF but not for OCSF in the elderly. The severity of odontoid cysts was found to be a cBMD-independent factor associated with A&D type II TOFs. However, degenerative changes in the odontoid neighboring joints seem to be an epiphenomenon of bone loss and older age but do not independently predispose for TOF. © 2017 American Society for Bone and Mineral Research.

3D ultrasound registration-based visual servoing for neurosurgical navigation.

PURPOSE: We present a fully image-based visual servoing framework for neurosurgical navigation and needle guidance. The proposed servo-control scheme allows for compensation of target anatomy movements, maintaining high navigational accuracy over time, and automatic needle guide alignment for accurate manual insertions. METHOD: Our system comprises a motorized 3D ultrasound (US) transducer mounted on a robotic arm and equipped with a needle guide. It continuously registers US sweeps in real time with a pre-interventional plan based on CT or MR images and annotations. While a visual control law maintains anatomy visibility and alignment of the needle guide, a force controller is employed for acoustic coupling and tissue pressure. We validate the servoing capabilities of our method on a geometric gel phantom and real human anatomy, and the needle targeting accuracy using CT images on a lumbar spine gel phantom under neurosurgery conditions. RESULTS: Despite the varying resolution of the acquired 3D sweeps, we achieved direction-independent positioning errors of [Formula: see text] mm and [Formula: see text], respectively. Our method is capable of compensating movements of around 25 mm/s and works reliably on human anatomy with errors of [Formula: see text] mm. In all four manual insertions by an expert surgeon, a needle could be successfully inserted into the facet joint, with an estimated targeting accuracy of [Formula: see text] mm, superior to the gold standard. CONCLUSION: The experiments demonstrated the feasibility of robotic ultrasound-based navigation and needle guidance for neurosurgical applications such as lumbar spine injections.

Propionibacterium prosthetic joint infection: experience from a retrospective database analysis.

BACKGROUND: With improved diagnostic methods and longer prosthesis indwelling time, the frequency of diagnosed Propionibacterium prosthetic joint infections (PJI) is increasing. Data on clinical, microbiological, radiological and surgical treatment are limited, and importance of this organism in PJI is probably underestimated. MATERIALS AND METHODS: We retrospectively analyzed patients with PJI caused by Propionibacterium spp. diagnosed at our institution between 2000 and 2012. Patient data were retrieved through chart review, and the outcome was evaluated at patient follow-up visits. RESULTS: Of 15 included patients (median age 65 years, range 44-87), 8 hip, 4 shoulder, 2 knee and 1 ankle PJI were recorded. The median time from implantation to diagnosis of PJI was 44.2 months (range 2-180 months). Most PJI (8 patients, 53 %) were diagnosed late (>24 months after arthroplasty). Persistent pain was present in 13, local joint symptoms in 8, fever in 4 and sinus tract in 3 patients. Radiological signs of loosening were present in 11 patients (73 %). Organisms were detected in intraoperative biopsy (n = 5), sonication (n = 4) or preoperative joint puncture (n = 4). In three cases coinfection with a coagulase-negative staphylococcus was diagnosed. Revision surgery was performed in all cases. After a mean follow-up of 16 months after revision surgery (range 4-37 months), 14 patients (93 %) showed no signs or symptoms of infection and had a functional prosthesis; one patient experienced a new infection with another organism (Staphylococcus epidermidis). CONCLUSION: Patients with persistent postoperative pain and/or loosening of implants should be screened for PJI with low-virulent organisms such as Propionibacterium, including.

The effect of femoral component rotation on the five-year outcome of cemented mobile bearing total knee arthroplasty.

PURPOSE: Performing total knee replacement, accurate alignment and neutral rotation of the femoral component are widely believed to be crucial for the ultimate success. Contrary to absolute bone referenced alignment, using a ligament balancing technique does not automatically rotate the femoral component parallel to the transepicondylar axis. In this context we established the hypothesis that rotational alignment of the femoral component parallel to the transepicondylar axis (0° ± 3°) results in better outcome than alignment outside of this range. METHODS: We analysed 204 primary cemented mobile bearing total knee replacements five years postoperatively. Femoral component rotation was measured on axial radiographs using the condylar twist angle (CTA). Knee society score, range of motion as well as subjective rating documented outcome. RESULTS: In 96 knees the femoral component rotation was within the range 0 ± 3° (neutral rotation group), and in 108 knees the five-year postoperative rotational alignment of the femoral component was outside of this range (outlier group). Postoperative CTA showed a mean of 2.8° (±3.4°) internal rotation (IR) with a range between 6° external rotation (ER) and 15° IR (CI 95). No difference with regard to subjective and objective outcome could be detected. CONCLUSION: The present work shows that there is a large given natural variability in optimal rotational orientation, in this study between 6° ER and 15° IR, with numerous co-factors determining correct positioning of the femoral component. Further studies substantiating pre- and postoperative determinants are required to complete the understanding of resulting biomechanics in primary TKA.