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1.  Objective assessment, repeatability, and agreement of shoulder ROM with a 3D gyroscope 
Background
Assessment of shoulder mobility is essential for diagnosis and clinical follow-up of shoulder diseases. Only a few highly sophisticated instruments for objective measurements of shoulder mobility are available. The recently introduced DynaPort MiniMod TriGyro ShoulderTest-System (DP) was validated earlier in laboratory trials. We aimed to assess the precision (repeatability) and agreement of this instrument in human subjects, as compared to the conventional goniometer.
Methods
The DP is a small, light-weight, three-dimensional gyroscope that can be fixed on the distal upper arm, recording shoulder abduction, flexion, and rotation. Twenty-one subjects (42 shoulders) were included for analysis. Two subsequent assessments of the same subject with a 30-minute delay in testing of each shoulder were performed with the DP in two directions (flexion and abduction), and simultaneously correlated with the measurements of a conventional goniometer. All assessments were performed by one observer. Repeatability for each method was determined and compared as the statistical variance between two repeated measurements. Agreement was illustrated by Bland-Altman-Plots with 95% limits of agreement. Statistical analysis was performed with a linear mixed regression model. Variance for repeated measurements by the same method was also estimated and compared with the likelihood-ratio test.
Results
Evaluation of abduction showed significantly better repeatability for the DP compared to the conventional goniometer (error variance: DP = 0.89, goniometer = 8.58, p = 0.025). No significant differences were found for flexion (DP = 1.52, goniometer = 5.94, p = 0.09). Agreement assessment was performed for flexion for mean differences of 0.27° with 95% limit of agreement ranging from −7.97° to 8.51°. For abduction, the mean differences were 1.19° with a 95% limit of agreement ranging from −9.07° to 11.46°.
Conclusion
In summary, DP demonstrated a high precision even higher than the conventional goniometer. Agreement between both methods is acceptable, with possible deviations of up to greater than 10°. Therefore, static measurements with DP are more precise than conventional goniometer measurements. These results are promising for routine clinical use of the DP.
doi:10.1186/1471-2474-14-72
PMCID: PMC3614536  PMID: 23442604
Repeatability; Precision; Shoulder motion; Objective assessment; Dynaport; Gyroscope
2.  Closing-wedge high tibial osteotomy: survival and risk factor analysis at long-term follow up 
Background
Closing-wedge high tibial osteotomy (HTO) is successful for the treatment of medial osteoarthritis with varus malalignment. Preoperative risk factors for HTO failure are still controversial. The aim of this study was to elucidate the outcome and assess the influence of risk factors on long term HTO survival.
Methods
199 patients were retrospectively studied with a mean follow-up period of 9.6 years after HTO. HTO failure was defined as the need for conversion to TKA. Survival was analyzed with the Kaplan-Meier method. Knee function was evaluated by the Hospital for Special Surgery (HSS) score. HTO-associated complications were also assessed. Univariate, multivariate, and logistic regression analysis were performed to evaluate the influence of age, gender, BMI, preoperative Kellgren-Lawrence osteoarthritis grade, and varus angle on HTO failure.
Results
39 complications were recorded. Thus far, 36 HTOs were converted to TKA. The survival of HTO was 84% after 9.6 years. Knee function was considered excellent or good in 64% of patients. A significant preoperative risk factor for HTO failure was osteoarthritis, Kellgren-Lawrence grade >2.
Conclusion
HTO provides good clinical results in long-term follow-up. Preoperative osteoarthritis Kellgren-Lawrence grade >2 is a significant predictive risk factor for HTO failure. Results of HTO may be improved by careful patient selection. Complications associated with HTO should not be underestimated.
doi:10.1186/1471-2474-12-46
PMCID: PMC3046001  PMID: 21320313
3.  Navigation of total knee arthroplasty: rotation of components and clinical results in a prospectively randomized study 
Background
Navigation was introduced into total knee arthroplasty (TKA) to improve accuracy of component position, function and survival of implants. This study was designed to assess the outcome of navigated TKA in comparison with conventional implantation with the focus on rotational component position and clinical mid-term results.
Methods
In a prospectively randomized single-blinded approach, 90 patients with primary gonarthrosis were assigned to three different groups. Thirty patients each were assigned to NexGen LPS without and with navigation (groups 1 and 2), and 30 patients to navigation with the Stryker Scorpio PS (group 3). The navigation system used was the imageless Stryker KneeTrac, version 1.0. Clinical outcome was assessed by a blinded observer applying the Knee Society Score (KSS) and a visual analogue scale (VAS) for pain. CT scans and radiographs were conducted prior to and 12 weeks after index surgery.
Results
Seventy-nine patients were available for clinical evaluation at 3 ± 0.4 years follow-up. Four implants had to be revised for early loosening or infection (4.4%). Four patients had died and three patients were not able to follow the invitation for clinical assessment. Functional results in the KSS were significantly lower after navigated TKA. Operation time and incisions with navigation were significantly longer. Significantly less radiological outliers with navigation were found for coronal alignment of the femur, only.
Conclusion
In this series, no beneficial effect for navigation in TKA could be shown assessing clinical data, as functional results in the presented series seemed to be lower after first generation navigated TKA. The clinical mid- to long-term value of navigation remains to be evaluated in larger patient series or meta-analyses at longer follow-up.
Trial registration number
DRKS 00000430
doi:10.1186/1471-2474-12-16
PMCID: PMC3025928  PMID: 21235810
4.  An ex vivo continuous passive motion model in a porcine knee for assessing primary stability of cell-free collagen gel plugs 
Background
Primary stability of cartilage repair constructs is of the utmost importance in the clinical setting but few continuous passive motion (CPM) models are available. Our study aimed to establish a novel ex vivo CPM animal model and to evaluate the required motion cycles for testing the mechanical properties of a new cell-free collagen type I gel plug (CaReS®-1S).
Methods
A novel ex vivo CPM device was developed. Full-thickness cartilage defects (11 mm diameter by 6 mm deep) were created on the medial femoral condyle of porcine knee specimens. CaReS®-1S was implanted in 16 animals and each knee underwent continuous passive motion. After 0, 2000, 4000, 6000, and 8000 motions, standardized digital pictures of the grafts were taken, focusing on the worn surfaces. The percentage of worn surface on the total CaReS®-1S surface was evaluated with image processing software.
Results
Significant differences in the worn surface were recorded between 0 and 2000 motion cycles (p < 0.0001). After 2000 motion cycles, there was no significant difference. No total delamination of CaReS®-1S with an empty defect site was recorded.
Conclusion
The ex vivo CPM animal model is appropriate in investigating CaReS®-1S durability under continuous passive motion. 2000 motion cycles appear adequate to assess the primary stability of type I collagen gels used to repair focal chondral defects.
doi:10.1186/1471-2474-11-283
PMCID: PMC3019221  PMID: 21159196
5.  Expression of matrix metalloproteinases 1, 3, and 9 in degenerated long head biceps tendon in the presence of rotator cuff tears: an immunohistological study 
Background
Long head biceps (LHB) degeneration, in combination with rotator cuff tears, can be a source of chronic shoulder pain. LHB tenotomy reduces pain and improves joint function although the pathophysiological context is not well understood. Tendon integrity depends on the extracellular matrix (ECM), which is regulated by matrix metalloproteinases (MMP). It is unclear which of these enzymes contribute to LHB but we chose to study MMP 1, 3, and 9 and hypothesized that one or more of them may be altered in LHB, whether diagnosed preoperatively or intraoperatively. We compared expression of these MMPs in both LHB and healthy tendon samples.
Methods
LHB samples of 116 patients with degenerative rotator cuff tears were harvested during arthroscopic tenotomy. Patients were assigned to 4 groups (partial thickness tear, full thickness tear, cuff arthropathy, or control) based upon intraoperative findings. Partial and full thickness tears were graded according to Ellman and Bateman's classifications, respectively. MMP expression was determined by immunohistochemistry.
Results
MMP 1 and 9 expression was significantly higher in the presence of rotator cuff tears than in controls whereas MMP 3 expression was significantly decreased. MMP 1 and 9 expression was significantly higher in articular-sided than bursal-sided partial thickness tears. No significant association was found between MMP 1 and 9 expression and full thickness tears, and the extent of the cuff tear by Bateman's classification.
Conclusion
Increased MMP 1 and 9 expression, and decreased MMP 3 expression are found in LHB degeneration. There is a significant association between the size and location of a rotator cuff tear and MMP expression.
doi:10.1186/1471-2474-11-271
PMCID: PMC2998463  PMID: 21108787
6.  The association between retraction of the torn rotator cuff and increasing expression of hypoxia inducible factor 1α and vascular endothelial growth factor expression: an immunohistological study 
Background
Differing levels of tendon retraction are found in full-thickness rotator cuff tears. The pathophysiology of tendon degeneration and retraction is unclear. Neoangiogenesis in tendon parenchyma indicates degeneration. Hypoxia inducible factor 1α (HIF) and vascular endothelial growth factor (VEGF) are important inducers of neoangiogenesis. Rotator cuff tendons rupture leads to fatty muscle infiltration (FI) and muscle atrophy (MA). The aim of this study is to clarify the relationship between HIF and VEGF expression, neoangiogenesis, FI, and MA in tendon retraction found in full-thickness rotator cuff tears.
Methods
Rotator cuff tendon samples of 33 patients with full-thickness medium-sized rotator cuff tears were harvested during reconstructive surgery. The samples were dehydrated and paraffin embedded. For immunohistological determination of VEGF and HIF expression, sample slices were strained with VEGF and HIF antibody dilution. Vessel density and vessel size were determined after Masson-Goldner staining of sample slices. The extent of tendon retraction was determined intraoperatively according to Patte's classification. Patients were assigned to 4 categories based upon Patte tendon retraction grade, including one control group. FI and MA were measured on standardized preoperative shoulder MRI.
Results
HIF and VEGF expression, FI, and MA were significantly higher in torn cuff samples compared with healthy tissue (p < 0.05). HIF and VEGF expression, and vessel density significantly increased with extent of tendon retraction (p < 0.05). A correlation between HIF/VEGF expression and FI and MA could be found (p < 0.05). There was no significant correlation between HIF/VEGF expression and neovascularity (p > 0.05)
Conclusion
Tendon retraction in full-thickness medium-sized rotator cuff tears is characterized by neovascularity, increased VEGF/HIF expression, FI, and MA. VEGF expression and neovascularity may be effective monitoring tools to assess tendon degeneration.
doi:10.1186/1471-2474-11-230
PMCID: PMC2958987  PMID: 20932296
7.  TKA following high tibial osteotomy versus primary TKA - a matched pair analysis 
Background
High tibial osteotomy (HTO) is a well established technique for the treatment of medial osteoarthritis of the knee with varus malalignment. Results of total knee arthroplasty (TKA) after previous HTO are still discussed controversially. The aim of this study was to elucidate the clinical and radiological results as well as perioperative data of prior HTO on TKA.
Methods
Forty-one TKA after HTO were compared to 41 primary TKA at minimum of six years follow-up. Patients were matched according to age, gender, follow-up, etiology, and prosthetic design. Surgical data and complications were evaluated. Clinical outcome was assessed using a number of clinical scores and the visual analogue scale (VAS) for pain. X-rays were evaluated by the method of the American Knee Society. The patellar position was measured by the Insall-Salvati ratio.
Results
There was no significant difference in mean operation time (p = 0.47) and complication rate (p = 0.08). The Knee Score of the KSS (p = 0.0007) and the ROM (p = 0.006 for extension and p = 0.004 for flexion, respectively) were significantly better in the control group. Mid-term results of the VAS, WOMAC, Lequesne, UCLA, Feller's Patellar Score and SF-36 showed no significant difference. Femoral and tibial component alignment were similar in both groups. One tibial component showed suspect radiolucencies in the HTO group. The Insall-Salvati ratio showed three patients with patella alta and one patient with patella baja in the HTO group. At latest follow-up all implants were still in place.
Conclusions
Evaluating the clinical and radiological outcome, significant differences were only detected for range of motion and the Knee Score of the KSS. The present study suggests that the results of TKA with and without prior HTO are mainly identical. Although patients with a previous HTO had more complications, no statistically significant differences were noted with this group size.
doi:10.1186/1471-2474-11-207
PMCID: PMC2944221  PMID: 20840744
8.  The relevance of long head biceps degeneration in the presence of rotator cuff tears 
Background
Long head biceps (LHB) degeneration in combination with rotator cuff tears can be a source of chronic shoulder pain. LHB tenotomy is an approved surgical procedure for pain reduction and improvement of joint function, however, the pathophysiology of LHB degeneration is not fully understood. In the literature, neoangiogenesis in tendon tissue has previously been shown to be associated with tendon degeneration. Vascular Endothelial Growth Factor (VEGF) is an important inducer of neoangiogenesis. The hypotheses are first that an elevated VEGF expression and vessel density can be found in degenerated LHB tissue and second that there is a relation between VEGF expression, vessel density and the different types of rotator cuff tears.
Methods
LHB samples of 116 patients with degenerative rotator cuff tears were harvested during arthroscopic tenotomy. The samples were dehydrated and paraffin embedded. VEGF expression was determined using immunohistochemistry. Vessel density and vessel size were determined on Masson-Goldner stained tissue sections. On the basis of intraoperative findings, patients were assigned to 4 different groups (control group, partial thickness rotator cuff tear, full thickness rotator cuff tear and cuff arthropathy). Partial thickness rotator cuff tears were classified according to Ellman grade I-III, full thickness rotator cuff tears according to Bateman's classification (grade I-IV). The control group consisted of eight healthy tendon samples.
Results
VEGF expression in the LHB was significantly higher in the presence of rotator cuff tears than in healthy tendons (p < 0.05) whereas vessel density and vessel size were significantly higher in the LHB of patients with cuff arthropathy (p < 0.05). Furthermore, there was significantly higher VEGF expression in LHB samples from patients with articular-sided compared to bursal-sided partial thickness rotator cuff tears (p < 0.05). No significant dependence was found between VEGF expression, vessel size and vessel density in LHB of patients with full thickness rotator cuff tears and the extent of the cuff tear following Bateman's classification.
Conclusion
Elevated VEGF expression can be detected in degenerated LHB tissue. The quantity of VEGF expression and vessels are related to the extent of LHB degeneration.
doi:10.1186/1471-2474-11-191
PMCID: PMC2936349  PMID: 20799939
9.  Co-occurrence of outlet impingement syndrome of the shoulder and restricted range of motion in the thoracic spine - a prospective study with ultrasound-based motion analysis 
Background
Shoulder complaints, and especially the outlet-impingement syndrome, are a common condition. Among other things, poor posture has been discussed as a cause. A correlation between impingement syndrome and restricted mobility of the thoracic spine (T) has been described earlier, but there has been no motion analysis of the thoracic spine to show these correlations. In the present prospective study, we intended to find out whether there is a significant difference in the thoracic sagittal range of motion (ROM) between patients with a shoulder outlet impingement syndrome and a group of patients who had no shoulder pathology. Secondly, we wanted to clarify whether Ott's sign correlates with ultrasound topometric measurements.
Methods
Two sex- and age-matched groups (2 × n = 39) underwent a clinical and an ultrasound topometric examination. The postures examined were sitting up straight, sitting in maximal flexion and sitting in maximal extension. The disabilities of the arm, shoulder and hand (DASH) score (obtained by means of a self-assessment questionnaire) and the Constant score were calculated. Lengthening and shortening of the dorsal projections of the spine in functional positions was measured by tape with Ott's sign.
Results
On examination of the thoracic kyphosis in the erect seated posture there were no significant differences between the two groups (p = 0.66). With ultrasound topometric measurement it was possible to show a significantly restricted segmental mobility of the thoracic spine in the study group compared with the control group (p = 0.01). An in-depth look at the mobility of the subsegments T1-4, T5-8 and T9-12 revealed that differences between the groups in the mobility in the lower two sections of the thoracic spine were significant (T5-8: p = 0.03; T9-12: p = 0.02). The study group had an average Constant score of 35.1 points and the control group, 85.5 (p < 0.001). On the DASH score the patient group reached 34.2 points and the control group, 1.4 (p < 0.001). The results of Ott's sign differed significantly between the two collectives (p = 0.0018), but showed a weak correlation with the ultrasound topometric measurements (study group flexion/extension: r = 0.36/0.43, control group flexion/extension: r = 0.29/0.26).
Conclusion
The mobility of the thoracic spine should receive more attention in the diagnosis and therapy of patients with shoulder outlet impingement syndrome.
doi:10.1186/1471-2474-11-135
PMCID: PMC2903509  PMID: 20587014
10.  Results of the cementless Plasmacup in revision total hip arthroplasty: a retrospective study of 72 cases with an average follow-up of eight years 
Background
There are multiple revision implant systems currently available for socket revision in revision total hip arthroplasty. Up until now, not all of these systems have been followed up with regards to their long-term use as a revision implantation.
For the first time, this study presents the hemispherical porous-coated socket Plasmacup SC, produced by Aesculap, Tuttlingen, Germany, and the clinical and radiological mid-term results of this revision cup implant.
Methods
Over a period of ten years the Plasmacup SC press-fit-cup was used as a revision implant in 72 consecutive aseptic cases which were included in this retrospective study. The mean follow-up period was 8 years. Bone graft transplantation was performed in 32% of all cases. In 90%, the cup was fixed with additional screws. The follow-up radiographs were analysed with regards to cup migration, osteointegration and osteolysis in the DeLee zones using a computer aided program taking the teardrop figure as a main point of reference. For clinical evaluation the Harris-Hip-Score and the WOMAC-Score were utilized.
Results
At the follow up examination, the mean Harris-Hip-Score was 83.5 points and the mean WOMAC-Score 34.7 points. 93% of all patients were satisfied with the result of the operation. No aseptic cup loosening could be observed and only one cup had to be removed due to infection. No significant longitudinal or transversal cup migration could be observed.
Conclusion
Aesculap's Plasmacup SC is suitable as a cementless cup revision implant. There is stable cup osteointegration, post press-fit implantation, even in the case of major acetabular bone defects.
doi:10.1186/1471-2474-11-101
PMCID: PMC2887774  PMID: 20507578
11.  Damages of the tibial post in constrained total knee prostheses in the early postoperative course – a scanning electron microscopic study of polyethylene inlays 
Background
Investigation of the risk of fracture of the polyethylene (PE) inlay in constrained total knee prostheses.
Methods
Three unused and seven polyethylene inlays that had been implanted in a patient's knee for an average of 25.4 months (min 1.1 months, max 50.2 months) were investigated using scanning electron microscopy (SEM). All inlays were of the same type and size (Genesis II constrained, Smith & Nephew). The PE surface at the transition from the plateau to the post was analyzed.
Results
The unused inlays had fissure-free surfaces. All inlays that had been implanted in a patient's knee already had distinct fissures at the front and backside of the post.
Conclusion
The fissures of the transition from the plateau to the post indicated a loading-induced irreversible mechanical deformation and possibly cause the fracture of the inlay.
doi:10.1186/1471-2474-9-83
PMCID: PMC2435533  PMID: 18547408

Results 1-11 (11)