Biomechanical forces exert anabolic effects on osteoblasts by activation of SMAD 1/5/8 through type 1 BMP receptor

Osteoblasts are mechanosensitive cells, which respond to biomechanical stimuli to regulate the bone structure through anabolic and catabolic gene regulation. To examine the effects of mechanical forces on the osteogenic responses through the SMAD signaling in osteoblasts, the cells were cultured in well-characterized mechanoresponsive 3-D scaffolds and exposed to 10% dynamic compressive strain (Cmp) at 1 Hz. Subsequently, SMAD phosphorylation and osteogenic gene induction was examined. Osteoblasts cultured in 3-D scaffolds exhibited increased constitutive SMAD 1/5/8 phosphorylation, as compared to monolayers cultures. This SMAD 1/5/8 phosphorylation was further upregulated after 10, 30 and 60 min in response to Cmp, exhibiting a peak activation at 30 min. No significant changes in SMAD2 phosphorylation were observed, suggesting signals generated by Cmp may not activate the Transforming Growth Factor-β signaling cascade. Subsequently, biomechanical stimulation-induced SMAD 1/5/8 phosphorylation upregulated the expression of osteogenic genes such as Osteoprotegrin, Msx2 and Runx2. Dorsomorphin, a selective inhibitor of the bone morphogenetic protein (BMP) receptor type 1 (BMPR1), blocked Cmp-induced SMAD 1/5/8 phosphorylation, as well as Osteoprotegrin, Msx2 and Runx2 gene expression. Collectively, the present findings demonstrate that biomechanical stimulation of osteoblasts activates SMAD 1/5/8 in the BMP signaling pathway through BMPR1 and may enhance osteogenesis by upregulating SMAD-dependent osteogenic genes.

Identifying patients with axial spondyloarthritis in primary care: how useful are items indicative of inflammatory back pain?

Background

The value of clinical items defining inflammatory back pain to identify patients with axial spondyloarthritis (SpA) in primary care is unclear.

Objective

To identify predictive clinical parameters for a diagnosis of axial SpA in patients with chronic back pain presenting in primary care.

Methods

Consecutive patients aged <45 years (n=950) with back pain for >2 months who presented to orthopaedic surgeons (n=143) were randomised based on four key questions for referral to rheumatologists (n=36) for diagnosis.

Results

The rheumatologists saw 322 representative patients (mean age 36 years, 50% female, median duration of back pain 30 months). 113 patients (35%) were diagnosed as axial SpA (62% HLA B27+), 47 (15%) as ankylosing spondylitis (AS) and 66 (21%) as axial non-radiographic SpA (nrSpA). Age at onset ≤35 years, improvement by exercise, improvement with non-steroidal anti-inflammatory drugs, waking up in the second half of the night and alternating buttock pain were identified as most relevant for diagnosing axial SpA by multiple regression analysis. Differences between AS and nrSpA were detected. No single item was predictive, but ≥3 items proved useful for good sensitivity and specificity by receiver operating characteristic modelling.

Conclusion

This study shows that a preselection in primary care of patients with back pain based on a combination of clinical items is useful to facilitate the diagnosis of axial SpA.

The role of the transverse acetabular ligament for acetabular component orientation in total hip replacement

Orientation of the native acetabular plane as defined by the transverse acetabular ligament (TAL) and the posterior labrum was measured intra-operatively using computer-assisted navigation in 39 hips. In order to assess the influence of alignment on impingement, the range of movement was calculated for that defined by the TAL and the posterior labrum and compared with a standard acetabular component position (abduction 45°/anteversion 15°).

With respect to the registration of the plane defined by the TAL and the posterior labrum, there was moderate interobserver agreement (r = 0.64, p < 0.001) and intra-observer reproducibility (r = 0.73, p < 0.001). The mean acetabular component orientation achieved was abduction of 41° (32° to 51°) and anteversion of 18° (−1° to 36°). With respect to the Lewinnek safe zone (abduction 40° ±10°, anteversion 15° ±10°), 35 of the 39 acetabular components were within this zone. However, there was no improvement in the range of movement (p = 0.94) and no significant difference in impingement (p = 0.085).

Alignment of the acetabular component with the TAL and the posterior labrum might reduce the variability of acetabular component placement in total hip replacement. However, there is only a moderate interobserver agreement and intra-observer reliability in the alignment of the acetabular component using the TAL and the posterior labrum. No reduction in impingement was found when the acetabular component was aligned with the TAL and the posterior labrum, compared with a standard acetabular component position.

A five to seven year follow-up comparing computer-assisted vs freehand TKR with regard to clinical parameters

PURPOSE

Computer-assisted knee surgery has become established in routine clinical practice. Still, there is no study investigating midterm clinical outcome after five to seven years postoperatively. We aimed to test the hypothesis that there is no difference either for subjective [Western Ontario and McMaster Universities (WOMAC) scores] or for objective (Knee Society Score, degree of flexion) criteria between computer-assisted total knee replacement (TKR) and freehand TKR after 5.6-7.3 years.

METHODS

We performed a matched-pair analysis; 100 patients who received a primary TKR were investigated after a median follow-up of 6.25 years. Group A was operated on with the support of a computer system, while surgery on patients in group B was performed with the freehand technique. We determined WOMAC Score, Knee Society Score and degree of flexion.

RESULTS

Overall we found similar results for WOMAC Score [group A: 42.98 (SD 13.80); group B: 41.54 (SD 15.01; p = 0.62)], Knee Society Score [group A: 168.20 (SD 21.94); group B: 166.60 (SD 21.44; p = 0.71)] and range of motion [group A: 106° (SD 9.19); group B 107° (SD 7.44; p = 0.62)].

CONCLUSIONS

No significant differences in midterm clinical outcome were found after TKR performed in the freehand vs computer-assisted technique.

Prospective single-arm, multi-center trial of a patient-specific interpositional knee implant: early clinical results

BACKGROUND

The treatment of unicompartmental arthritis in younger patients is challenging. The aim of this study is to report final safety and efficacy analysis results for the iForma patient-specific interpositional device, which is designed for the treatment of isolated medial or lateral compartment arthritis of the knee.

METHODS

From June 2005 to June 2008 78 subjects (42 men, 36 women) received an iForma implant. The mean age was 53 years, the mean Body Mass Index 29.0. We surveyed the WOMAC scores, the visual analog pain scale and the Knee Society Scores.

RESULTS

The mean follow up was 16.4 months. The mean WOMAC knee scores increased from 48.3 before surgery to 71.3 after 24 months. A reduction in pain was achieved for all five pain measures using a standard visual analog scale (VAS). Knee Society Knee Score improved from 39.2 before to 61.9 24 month after surgery. The Knee Society Function Scores improved form preoperative 64.5 to 82.5 2 years postoperative. The preoperative range of motion could be restored. The overall revision rate was 24%. 15 implants were removed early, 4 knees were revised without implant removal.

CONCLUSION

Within narrow indication of patients with unicompartmental disease, the iForma device can provide improvement in knee function and reduction in pain, however, with a significant higher risk of early revision compared to traditional arthroplasty. Respecting this limitation it may be an alternative option for arthritic patients with unicompartmental disease who have contraindications to High Tibial Osteotomy or are too young for knee replacement; the iForma device further has the distinct advantage of time and cost saving compared to those procedures.

Surgical synovectomy decreases density of sensory nerve fibers in synovial tissue of non-inflamed controls and rheumatoid arthritis patients

Surgical synovectomy is a technique to treat synovitis and pain in patients with rheumatoid arthritis (RA) resistant to DMARDs or therapy with biologics. Indication to synovectomy is subject to tight cooperation of orthopaedic surgeons and rheumatologists. It was thought that synovectomy leads to a reduction of sensory nerve fibers, called sensory denervation. Since sensory denervation after synovectomy has never been histologically tested, we aimed to investigate sensory and sympathetic innervation in synovial tissue before and after synovectomy. Eight non-inflamed control subjects and eight patients with RA were included in this study with a two-stage synovectomy approach (interval 40–50 days). Nerve fibers and cells in synovial tissue were detected and counted using immunofluorescence. Density of sympathetic nerve fibers did not change after synovectomy, whereas density of sensory nerve fibers decreased in all control subjects and seven of eight patients with RA. In parallel, the density of synovial cells increased after synovectomy in all control subjects and six of eight RA patients, which is indicative of a wound healing response. In one female RA patient, density of sensory nerve fibers increased and a very marked rise of cellular density was observed, too. This indicates that probably not all patients profit from surgical synovectomy. The majority of patients (94%) demonstrated sensory denervation after surgical synovectomy accompanied by a wound healing cell response. This study can help to explain the positive effects of surgical synovectomy which usually leads to pain reduction and improved mobility.

[Importance of computer-assisted navigation in total knee arthroplasty - results of a nationwide survey in Germany]

AIM

Total knee arthroplasty is one of the standard procedures in severe osteoarthritis of the knee. Computer-assisted navigation systems became more popular in the last decade. Navigation systems improve the component positioning and the alignment in total knee arthroplasties. The aim of this survey was to capture the actual trend in computer-assisted total knee arthroplasties in Germany and to discuss the results in comparison to the current literature.

METHODS

A questionnaire form was sent to 506 orthopaedic and trauma surgery departments in Germany. The first part of the survey included general questions about the department and total knee arthroplasties. The surgeons were asked about their application behaviour and their rating of computer-assisted navigation in total knee arthroplasty in the second part. Questions concerning total knee arthroplasties, unicondylar knee arthroplasties and revision total knee arthroplasties were included in the form.

RESULTS

194 of the departments returned the questionnaire. A total of 39 941 knee arthroplasty surgeries were performed in these departments. 35 624 of these surgeries were primary knee arthroplasties including 32 789 total knee arthroplasties and 2835 unicondylar knee arthroplasties. In addition, 4317 revision total knee arthroplasties were performed by the respondents. 60 % of the departments used a computer-assisted navigation system. In synopsis 29 % of the primary total knee arthroplasties, 4 % of the unicondylar knee arthroplasties and 7 % of the revision knee arthroplasties were performed with a computer-assisted navigation system. Minimal invasive surgery was performed in 31 % of the departments and 36 % of these surgeries were done with navigation-assistance. The "ligament-balanced" procedure was the most common used technique to determine the femur rotation in navigated total knee arthroplasties. In 75 % of navigated total knee arthroplasties cemented components were implanted. Overall 65 % of respondents approved of navigation-assisted surgeries and 77 % saw an improved precision by this technique. The number of computer-assisted navigation uses in surgeries is increasing in 34 % of the departments and decreasing in 13 %.

CONCLUSION

The computer-assisted navigation in total knee arthroplasties is a frequently used technique. The most respondents support the application of navigation-assisted knee arthroplasties and indicate an improved outcome measured by the postoperative alignment. Nevertheless, long-term results are needed for a final evaluation of navigation-assisted surgery.

[Clinical pathway "total knee arthroplasty"]

Total knee arthroplasty is a standardized intervention in orthopedic departments. Due to the standard character of the procedure it is predestinated to be performed in a clinical pathway. We developed a clinical pathway for total knee arthroplasty and aim to show the details of it and discuss it together with the current literature. Total knee arthroplasty is a standardized procedure and is therefore predestinated to be included in a clinical pathway. The team consists of different groups which are combined in this path to work together in a very structured and standardized manner. We describe and discuss our clinical pathway for total knee arthroplasty and the initial experiences which are very promising.

[Clinical pathway - conservative back pain treatment]

Back pain is a very common clinical picture. The causes are often not only somatic, which generally has led to a biopsychosocial understanding of this disease. Therefore, it is necessary to employ a multimodal treatment approach to achieve effective and longer-lasting relief. Such a concept requires the cooperation of multiple disciplines in a sophisticated and strongly organized manner. In our clinic we have developed a clinical pathway for conservative back pain treatment that avoids the use of too much time by careful coordination of the therapy elements. It has proven to be a successful tool for the efficient treatment of patients with primarily somatically caused back pain. The following article describes this clinical pathway.

Fatigue fracture of the hinge pin in a semi-constrained total knee arthroplasty: a case report

Material failure is a rare complication in total knee arthroplasty (TKA). This case report shows a fatigue fracture of the hinge pin as a consequence of a postoperative persisting valgus deviation in a semi-constrained TKA.

[Femur first in hip arthroplasty--the concept of combined anteversion]

BACKGROUND

The concept of combined anteversion for total hip arthroplasty (THA) proposes a relationship between the cup and stem components that theoretically maximises the postoperative range of motion and minimises the risk for impingement of the joint. Using computer-assisted navigation tools, an anteversion angle of the cup component can be made to be dependent on the antetorsion angle of the stem component (or vice versa). We studied how this functional concept would be different from the traditional cup placement according to the Lewinnek safe zone.

PATIENTS AND METHODS

We prospectively reviewed 42 patients (42 hips) who underwent imageless, computer-assisted THA with cementless implants due to osteoarthritis between May and October 2008. Using computer navigation, we determined the cup anteversion with optimised containment and measured femoral stem antetorsion. Our goal was to implant the original implants with a combined anteversion of 37 degrees.

RESULTS

Mean cup anteversion was 22.5 degrees, mean combined anteversion was 35.2 degrees. Femoral antetorsion ranged from -13 to 38 degrees (mean: 18 degrees). Mean anteversion of the trial cup with optimised containment was 15.9 degrees and therefore close to the recommendation according to the Lewinnek safe zone. The total postoperative range of motion (flexion, extension, abduction, internal/external rotation) as measured with the navigation system intraoperatively was 209 degrees compared to 94 degrees measured clinically preoperatively. No THA dislocation occurred during the test.

CONCLUSION

The combined anteversion concept results in a cup position with more anteversion when compared to the traditional cup placement according to the Lewinnek safe zone. In this context, modern navigation techniques open a new frontier for an optimised component position. Placing the cup and stem in relation to the anteversion for both components allows consideration of the patient-specific biomechanics.

Comparison of two accelerated clinical pathways - after total knee replacement how fast can we really go?

Objective: To evaluate whether a further optimization of an existing accelerated clinical pathway protocol after total knee replacement is feasible and improves postoperative outcome.

Design: Prospective, parallel group design.

Setting: Orthopaedic University Medical Centre.

Patients: A total of 143 patients, scheduled for unilateral primary total knee replacement under perioperative regional analgesia.

Intervention: Sixty-seven patients received an optimized accelerated clinical pathway including patient-controlled regional analgesia pumps, ultra-early/doubled physiotherapy and motor-driven continuous passive motion machine units. Seventy-six patients received a standard accelerated clinical pathway.

Main measures: Feasibility was defined as the proportion of patients successfully completing the assigned pathway. Early postoperative pain on a visual analogue scale, consumption of regional anaesthetics, knee range of motion, time out of bed, non-stop walking distance/stair climbing, circumference measurement and Knee Society Score on the operated leg. Possible discharge according to an own discharge checklist.

Results: All patients assigned to both groups successfully completed this pathway. Patients in the optimized pathway showed significant benefits regarding stair climbing/walking distance/time out of bed/circumference measurements of the thigh/Knee Society function score on the fifth postoperative day and stair climbing/ circumference measurements of the thigh on the eighth postoperative day, and reduction of the consumption of regional anaesthetics. No significant reduction in length of stay was observed.

Conclusions: Early postoperative functional process indicators tended to be higher within the optimized pathway group, but the main effects flattened over the course of the first eight postoperative days.

[Persisting pain after open articulosynovectomy--gossypiboma]

We report about a 44-year-old woman who presented at our Orthopaedic Department suffering from persisting pain and a tumor of the right knee after open articulosynovectomy. MRI did not clarify the entity at all. The X-ray examination could identify an inlying compress after a synovectomy in 1999. The intra-articular foreign body could be removed by open revision surgery.

Long-term effects of chondrospheres on cartilage lesions in an autologous chondrocyte implantation model as investigated in the SCID mouse model

Microtraumata often lead to articular cartilage lesions. Due to the bradytrophic character of hyaline cartilage, these lesions are hardly repaired by the organism. Autologous chondrocyte implantation (ACI) was established for restoring isolated structural cartilage defects in knee joints. However, results are not always convincing. Human chondrocytes from patients undergoing total knee arthroplasty were cultured in monolayer followed by condensing single chondrocytes to spheroids (chondrospheres). The integrative capacity of chondrospheres was examined by implanting them into lesions in human articular cartilage specimens and co-implanting them into SCID mice. Mice were sacrificed after 4, 12 and 24 weeks. HE and safranin O staining as well as immunohistochemistry using anti-S100, anti-collagen I and II antibodies were performed and analyzed using semiquantitative scores. Integration of the chondrospheres with the (native) cartilage matrix was analyzed by determining the percentage of adhering surface. With respect to long-term stability, the chondrocytes within chondrospheres showed a typical chondrocytic morphology. Immunohistochemically, a high collagen II production was detected. Over a time period of 24 weeks, an increasing content of collagen type II, glycosaminoglycans and collagenous fibers were found. Importantly, the newly synthesized cartilaginous matrix integrated continuously with the native cartilage lesion border. In conclusion, the presented data demonstrate that chondrospheres are able to restore and conserve their phenotype for at least 24 weeks under in vivo conditions. Moreover, chondrospheres adhere to full-thickness cartilage defects and appear to produce a cartilaginous extracellular matrix which fuses with native cartilage thus generating an autologous cartilage-like repair tissue.

[Ochronosis--a rare cause of secondary gonarthrosis]

Ochronosis is a manifestation of the rare disease alkaptonuria. The most common presentations include pain in the lumbar spine region starting during the 3rd decade, spreading over the large joints. There exists no curative therapy for the disease at the moment. In the long-term the patients will be dependent on total joint arthroplasty.