Sven Hoppe

Tenocytes of chronic rotator cuff tendon tears can be stimulated by platelet-released growth factors.

BACKGROUND Bone-to-tendon healing after rotator cuff repairs is mainly impaired by poor tissue quality. The tenocytes of chronic rotator cuff tendon tears are not able to synthesize normal fibrocartilaginous extracellular matrix (ECM). We hypothesized that in the presence of platelet-released growth factors (PRGF), tenocytes from chronically retracted rotator cuff tendons proliferate and synthesize the appropriate ECM proteins. MATERIALS AND METHODS Tenocytes from 8 patients with chronic rotator cuff tears were cultured for 4 weeks in 2 different media: standard medium (Iscoves Modified Dulbeccos Media + 10% fetal calf serum + 1% nonessential amino acids + 0.5 μg/mL ascorbic acid) and media with an additional 10% PRGF. Cell proliferation was assessed at 7, 14, 21, and 28 days. Messenger (m)RNA levels of collagens I, II, and X, decorin, biglycan, and aggrecan were analyzed using real time reverse-transcription polymerase chain reaction. Immunocytochemistry was also performed. RESULTS The proliferation rate of tenocytes was significantly higher at all time points when cultured with PRGF. At 21 days, the mRNA levels for collagens I, II, and X, decorin, aggrecan, and biglycan were significantly higher in the PRGF group. The mRNA data were confirmed at protein level by immunocytochemistry. CONCLUSIONS PRGFs enhance tenocyte proliferation in vitro and promote synthesis of ECM to levels similar to those found with insertion of the normal human rotator cuffs. CLINICAL RELEVANCE Biologic augmentation of repaired rotator cuffs with PRGF may enhance the properties of the repair tissue. However, further studies are needed to determine if application of PRGF remains safe and effective in long-term clinical studies. LEVEL OF EVIDENCE Basic Science Study, Cell Biology.

Long-Term Outcome After Monosegmental L4/5 Stabilization for Degenerative Spondylolisthesis With the Dynesys Device

Study Design:Retrospective analysis of prospectively collected clinical data. Objective:To assess the long-term outcome of patients with monosegmental L4/5 degenerative spondylolisthesis treated with the dynamic Dynesys device. Summary of Background Data:The Dynesys system has been used as a semirigid, lumbar dorsal pedicular stabilization device since 1994. Good short-term results have been reported, but little is known about the long-term outcome after treatment for degenerative spondylolisthesis at the L4/5 level. Methods:A total of 39 consecutive patients with symptomatic degenerative lumbar spondylolisthesis at the L4/5 level were treated with bilateral decompression and Dynesys instrumentation. At a mean follow-up of 7.2 years (range, 5.0–11.2 y), they underwent clinical and radiographic evaluation and quality of life assessment. Results:At final follow-up, back pain improved in 89% and leg pain improved in 86% of patients compared with preoperative status. Eighty-three percent of patients reported global subjective improvement. Ninety-two percent would undergo the surgery again. Eight patients (21%) required further surgery because of symptomatic adjacent segment disease (6 cases), late-onset infection (1 case), and screw breakage (1 case). In 9 cases, radiologic progression of spondylolisthesis at the operated segment was found. Seventy-four percent of operated segments showed limited flexion-extension range of <4 degrees. Adjacent segment pathology, although without clinical correlation, was diagnosed at the L5/S1 (17.9%) and L3/4 (28.2%) segments. In 4 cases, asymptomatic screw loosening was observed. Conclusions:Monosegmental Dynesys instrumentation of degenerative spondylolisthesis at L4/5 shows good long-term results. The rate of secondary surgeries is comparable to other dorsal instrumentation devices. Residual range of motion in the stabilized segment is reduced, and the rate of radiologic and symptomatic adjacent segment degeneration is low. Patient satisfaction is high. Dynesys stabilization of symptomatic L4/5 degenerative spondylolisthesis is a possible alternative to other stabilization devices.

Platelet released growth factors boost expansion of bone marrow derived CD34+ and CD133+ endothelial progenitor cells for autologous grafting

Stem cell based autologous grafting has recently gained mayor interest in various surgical fields for the treatment of extensive tissue defects. CD34+ and CD133+ cells that can be isolated from the pool of bone marrow mononuclear cells (BMC) are capable of differentiating into mature endothelial cells in vivo. These endothelial progenitor cells (EPC) are believed to represent a major portion of the angiogenic regenerative cells that are released from bone marrow when tissue injury has occurred. In recent years tissue engineers increasingly looked at the process of vessel neoformation because of its major importance for successful cell grafting to replace damaged tissue. Up to now one of the greatest problems preventing a clinical application is the large scale of expansion that is required for such purpose. We established a method to effectively enhance the expansion of CD34+ and CD133+ cells by the use of platelet-released growth factors (PRGF) as a media supplement. PRGF were prepared from thrombocyte concentrates and used as a media supplement to iscoves modified dulbeccos media (IMDM). EPC were immunomagnetically separated from human bone morrow monocyte cells and cultured in IMDM + 10% fetal calf serum (FCS), IMDM + 5%, FCS + 5% PRGF and IMDM + 10% PRGF. We clearly demonstrate a statistically significant higher and faster cell proliferation rate at 7, 14, 21, and 28 days of culture when both PRGF and FCS were added to the medium as opposed to 10% FCS or 10% PRGF alone. The addition of 10% PRGF to IMDM in the absence of FCS leads to a growth arrest from day 14 on. In histochemical, immunocytochemical, and gene-expression analysis we showed that angiogenic and precursor markers of CD34+ and CD133+ cells are maintained during long-term culture. In summary, we established a protocol to boost the expansion of CD34+ and CD133+ cells. Thereby we provide a technical step towards the clinical application of autologous stem cell transplantation.

Cement-augmented anterior screw fixation of Type II odontoid fractures in elderly patients with osteoporosis.

BACKGROUND CONTEXT Closed reduction and internal fixation by an anterior approach is an established option for operative treatment of displaced Type II odontoid fractures. In elderly patients, however, inadequate screw purchase in osteoporotic bone can result in severe procedure-related complications. PURPOSE To improve the stability of odontoid fracture screw fixation in the elderly using a new technique that includes injection of polymethylmethacrylat (PMMA) cement into the C2 body. STUDY DESIGN Retrospective review of hospital and outpatient records as well as radiographs of elderly patients treated in a university hospital department of orthopedic surgery. PATIENT SAMPLE Twenty-four elderly patients (8 males and 16 females; mean age, 81 years; range, 62-98 years) with Type II fractures of the dens. OUTCOME MEASURES Complications, cement leakage (symptomatic/asymptomatic), operation time, loss of reduction, pseudarthrosis and revision surgery, patient complaints, return to normal activities, and signs of neurologic complications were all documented. METHODS After closed reduction and anterior approach to the inferior border of C2, a guide wire is advanced to the tip of the odontoid under biplanar fluoroscopic control. Before the insertion of one cannulated, self-drilling, short thread screws, a 12 gauge Yamshidi cannula is inserted from anterior and 1 to 3 mL of high-viscosity PMMA cement is injected into the anteroinferior portion of the C2 body. During polymerization of the cement, the screws are further inserted using a lag-screw compression technique. The cervical spine then is immobilized with a soft collar for 8 weeks postoperatively. RESULTS Anatomical reduction of the dens was achieved in all 24 patients. Mean operative time was 64 minutes (40-90 minutes). Early loss of reduction occurred in three patients, but revision surgery was indicated in only one patient 2 days after primary surgery. One patient died within the first eight postoperative weeks, one within 3 months after surgery. In five patients, asymptomatic cement leakage was observed (into the C1-C2 joint in three patients, into the fracture in two). Conventional radiologic follow-up at 2 and 6 months confirmed anatomical healing in 16 of the 19 patients with complete follow-up. In two patients, the fractures healed in slight dorsal angulation; one patient developed a asymptomatic pseudarthrosis. All patients were able to resume their pretrauma level of activity. CONCLUSIONS Cement augmentation of the screw in Type II odontoid fractures in elderly patients is technically feasible in a clinical setting with a low complication rate. This technique may improve screw purchase, especially in the osteoporotic C2 body.

More accurate component alignment in navigated total knee arthroplasty has no clinical benefit at 5-year follow-up.

Background and purpose Computer navigation in total knee arthroplasty is somewhat controversial. We have previously shown that femoral component positioning is more accurate with computed navigation than with conventional implantation techniques, but the clinical impact of this is unknown. We now report the 5-year outcome of our previously reported 2-year outcome study. Methods 78 of initially 84 patients (80 of 86 knees) were clinically and radiographically reassessed 5 (5.1–5.9) years after conventional, image-based, and image-free total knee arthroplasty. The methodology was identical to that used preoperatively and at 2 years, including the Knee Society score (KSS) and the functional score (FS), and AP and true lateral standard radiographs. Results Although a more accurate femoral component positioning in the navigated groups was obtained, clinical outcome, number of reoperations, KSS, FS, and range of motion were similar between the groups. Interpretation The increased costs and time for navigated techniques did not translate into better functional and subjective medium-term outcome compared to conventional techniques.

The mean anatomical shape of the tibial plateau at the knee arthroplasty resection level: an investigation using MRI.

Clinical assessments after Total Knee Arthroplasty (TKA) show persisting pain after implantation in over 20% of patients. Impingement of soft tissue around the knee, due to imprecise geometry of the tibial implant, can be one reason for persisting ailment. Two hundred and thirty seven MRI scans were evaluated using an active contour detection algorithm (snake) to obtain a high-resolution mean anatomical shape of the tibial plateau. Differences between female and male, older and younger (<or=40/>40) and left and right averaged shapes were determined. The shapes obtained were asymmetric throughout. Absolute differences between the subgroups fell short of inter-individual variations represented by calculated one-sigma confidence intervals. Our results indicate that a differentiation in TKA tibial plateau design by gender, age, or side is of minor relevance.

The 100 Most Influential Publications in Cervical Spine Research.

Study Design. Bibliometric study of current literature. Objective. To identify and analyze the 100 most cited publications in cervical spine research. Summary of Background Data. The cervical spine is a dynamic field of research with many advances made within the last century. The literature has, however, never been comprehensively analyzed to identify and compare the most influential articles as measured by the number of citations. Methods. All databases of the Thomson Reuters Web of Knowledge were utilized in a two-step approach. First, the 150 most cited cervical spine studies up to and including 2014 were identified using four keywords. Second, all keywords related to the cervical spine found in the 150 studies (n = 38) were used to conduct a second search of the database. The top 100 most cited articles were hereby selected for further analysis of current and past citations, authorship, geographic origin, article type, and level of evidence. Results. Total citations for the 100 studies identified ranged from 173 to 879. They were published in the time frame 1952 to 2008 in a total of 30 different journals. Most studies (n = 42) were published in the decade 1991–2000. Level of evidence ranged from 1 to 5 with 39 studies in the level 4 category. A total of 13 researchers were first author more than once and nine researchers senior author more than once. The two-step approach with a secondary widening of search terms yielded an additional 27 studies, including the first ranking article. Conclusion. This bibliometric study is likely to include some of the most important milestones in the field of cervical spine research of the last 100 years. Level of Evidence: 3

Pedicle screw augmentation in osteoporotic spine: indications, limitations and technical aspects.

PurposeThe need for spinal instrumented fusion in osteoporotic patients is rising. In this review, we try to give an overview of the current spectrum of pedicle screw augmentation techniques, safety aspects and indications.MethodsReview of literature and discussion of indications, limitations and technical aspects.ResultsVarious studies have shown higher failure rates in osteoporotic patients, most probably due to reduced bone quality and a poor bone-screw interface. Augmentation of pedicle screws with bone cement, such as polymethylmethacrylate or calcium based cements, is one valid option to enhance fixation if required.ConclusionsCrucial factors for success in the use of augmented screws are careful patient selection, a proper technique and choice of the ideal cement augmentation option.

Epidemiology of Musculoskeletal Tuberculosis in an Area with High Disease Prevalence

Study Design Retrospective observational study. Purpose The aim of this study was to assess the distribution of age and site of infection in patients with musculoskeletal tuberculosis (TB) and determine the number of TB/human immunodeficiency virus (HIV) coinfections as well as the incidence of multidrugresistant (MDR) TB. Overview of Literature Of all TB cases, 1%–3% show skeletal system involvement and 30% are HIV coinfected. Although the reported distribution of skeletal TB is majorly in the spine, followed by the hip, knee, and foot/ankle, the epidemiology of extrapulmonary TB and especially musculoskeletal TB remains largely unknown, particularly in areas with a high prevalence of the disease. Methods This is a retrospective study of a consecutive series of patients admitted to a tertiary care facility in an area with the highest prevalence of TB worldwide. TB was confirmed on tissue biopsy with polymerase chain reaction testing (Xpert for Mycobacterium tuberculosis and rifampicin resistance), culturing, or histological analysis. Data were analyzed regarding demographic information, location of the disease, HIV coinfections, and drug resistance. Results In all, 125 patients (44 children; 35%) with a mean age of 27 years (range, 1–78 years) were included. Age peaks were observed at 5, 25, and 65 years. Spinal disease was evident in 98 patients (78%). There were 66 HIV-negative (53%) and 29 (23%) HIVpositive patients, and in 30 (24%), the HIV status was unknown. Five patients (4%) showed MDR TB. Conclusions The age distribution was trimodal, spinal disease was predominant, MDR TB rate in our cohort was high, and a large portion of TB patients in our hospital were HIV coinfected. Hence, spinal services with sufficient access to operating facilities are required for tertiary care facilities in areas with a high TB prevalence.

Lordoplasty: midterm outcome of an alternative augmentation technique for vertebral fractures.

OBJECTIVE Vertebroplasty and balloon kyphoplasty are effective treatment options for osteoporotic vertebral compression fractures but are limited in correction of kyphotic deformity. Lordoplasty has been reported as an alternative, cost-effective, minimally invasive, percutaneous cement augmentation technique with good restoration of vertebral body height and alignment. The authors report on its clinical and radiological midterm results. METHODS A retrospective review was conducted of patients treated with lordoplasty from 2002 to 2014. Inclusion criteria were clinical and radiological follow-up evaluations longer than 24 months. Radiographs were accessed regarding initial correction and progressive loss of reduction. Complications and reoperations were recorded. Actual pain level, pain relief immediately after surgery, autonomy, and subjective impression of improvement of posture were assessed by questionnaire. RESULTS Sixty-five patients (46 women, 19 men, age range 38.9-86.2 years old) were treated with lordoplasty for 69 vertebral compression and insufficiency fractures. A significant correction of the vertebral kyphotic angle (mean 13°) and segmental kyphotic angle (mean 11°) over a mean follow-up of 33 months (range 24-108 months) was achieved (p < 0.001). On average, pain was relieved to 90% of the initial pain level. In 24% of the 65 patients a second spinal intervention was necessary: 16 distant (24.6%) and 7 adjacent (10.8%) new osteoporotic fractures, 4 instrumented stabilizations (6.2%), 1 new adjacent traumatic fracture (1.5%), and 1 distant microsurgical decompression (1.5%). Cement leakage occurred in 10.4% but was only symptomatic in 1 case. CONCLUSIONS Lordoplasty appeared safe and effective in midterm pain alleviation and restoration of kyphotic deformity in osteoporotic compression and insufficiency fractures. The outcomes of lordoplasty are consistent with other augmentation techniques.