Novel single-loop and double-loop knot stitch in comparison with the modified Mason-Allen stitch for rotator cuff repair.

PURPOSE: In rotator cuff repair, strong and long-lasting suturing techniques that do not require additional implants are needed. This study examines the ultimate load to failure and the Young's modulus at the suture-tendon interface for a novel single-loop knot stitch and double-loop knot stitch. These values are compared to those of the modified Mason-Allen stitch. METHODS: Twenty-four infraspinatus muscles with tendons were dissected from porcine shoulders (twelve Goettingen minipigs). The preparations were randomly allocated to three groups of eight samples. Load-to-failure testing of the single-loop knot stitch, the double-loop knot stitch and the mMAS were performed using a Zwick 1446 universal testing machine (Zwick-Roell AG, Ulm, Germany). RESULTS: The highest ultimate load to failure for the three techniques occurred with the double-loop knot stitch with a median value of 382.2 N (range 291.8-454.2 N). These values were significantly higher than those of the single-loop knot stitch, which had a median value of 259.5 N (range 139.6-366.3 N) and the modified Mason-Allen stitch, which had a median value of 309.3 N (range 84.55-382.9 N). The values of the single-loop knot stitch and the modified Mason-Allen stitch did not differ significantly. Regarding the Young's modulus, no significant differences were found between the double-loop knot stitch with a median value of 496.02 N/mm² (range 400.4-572.6 N/mm²) and the modified Mason-Allen stitch with 498.5 N/mm² (range 375.5-749.2 N/mm²) with respect to the stiffness of the suture-tendon complex. The median value for the Young's modulus of the single-loop knot stitch of 392.1 N/mm² (range 285.7-510.6 N/mm²) was significantly lower than those of the double-loop knot stitch and modified Mason-Allen stitch. CONCLUSION: This in vitro animal study demonstrated that both the single-loop knot stitch and the double-loop knot stitch have excellent ultimate load-to-failure properties when used for rotator cuff repair. The introduced single-loop knot stitch and double-loop knot stitch offer an alternative to other common used stitch techniques in rotator cuff repair.

Characteristics of femorotibial joint geometry in the trochlear dysplastic femur.

The medial and lateral tibia plateau geometry has been linked with the severity of trochlear dysplasia. The aim of the present study was to evaluate the tibial slope and the femoral posterior condylar offset in a cohort of consecutive subjects with a trochlear dysplastic femur to investigate whether the condylar offset correlates with, and thus potentially compensates for, tibial slope asymmetry. Magnetic resonance imaging was used to assess the severity of trochlear dysplasia as well as the tibial slope and posterior offset of the femoral condyles separately for the medial and lateral compartment of the knee joint in 98 subjects with a trochlear dysplastic femur and 88 control subjects. A significant positive correlation was found for the medial tibial slope and the medial posterior condylar offset in the study group (r(2) = 0.1566; P < 0.001). This relationship was significant for all subtypes of trochlear dysplasia and was most pronounced in the severe trochlear dysplastic femur (Dejour type D) (r(2) = 0.3734; P = 0.04). No correlation was found for the lateral condylar offset and the lateral tibial slope in the study group or for the condylar offset and the tibial slope on both sides in the control group. The positive correlation between the medial femoral condylar offset and the medial tibial slope, that is, a greater degree of the medial tibial slope indicated a larger offset of the medial femoral condyle, appears to represent a general anthropomorphic characteristic of distal femur geometry in patients with a trochlear dysplastic femur.

Osteoarthritis of the carpometacarpal joint of the thumb: a new MR imaging technique for the standardized detection of relevant ligamental lesions.

OBJECTIVE: To assess ligament lesions and subluxations of the carpometacarpal joints of the thumbs (CMC I) of asymptomatic volunteers and of patients with CMC I osteoarthritis using advanced magnetic resonance imaging (MRI). MATERIALS AND METHODS: A total of 20 CMC I joints of 14 asymptomatic volunteers (6× both sides) and 28 CMC I joints of 22 patients (6× both sides) with symptomatic and X-ray-diagnosed osteoarthritis of CMC I joints were studied. During extension, flexion, abduction and adduction of the thumb, the anterior oblique (AOL), intermetacarpal (IML), posterior oblique (POL) and dorsal radial (DRL) ligaments were evaluated using 3-T MRI on two standard planes, and translation of metacarpal I (MC I) was assessed. RESULTS: The MRI demonstrated that ligament lesions of the AOL and IML are frequent. Isolated rupture of the AOL was found in 6 of 28 (21%), combined rupture of the AOL + IML in 5 of 28 (18%) and isolated IML rupture in 4 of 28 (14%) joints. The patients had a significantly increased dorsal translation of MC I during extension with a median of 6.4 mm vs. 5.4 mm in asymptomatic volunteers (p < 0.05). CONCLUSION: MRIs of CMC I in two standardized planes frequently show combined ligament ruptures. The dorsal subluxation of MC I, which is increased in patients, correlates with OA severity based on X-ray and can be quantified by MRI. For joint-preserving surgical procedures and for prosthesis implantation of the CMC I, we recommend performing an MRI in two planes of the thumb-extension and abduction-to evaluate the ligaments and dorsal subluxation of MC I.

Which patellae are likely to redislocate?

PURPOSE: The purpose of this study was to identify the risk factors for recurrent lateral patellar dislocations and to incorporate those factors into a patellar instability severity score. METHODS: Sixty-one patients [male/female 35/26; median age 19 years (range 9-51 years)] formed the study group for this investigation. Within the study group, 40 patients experienced a patellar redislocation within 24 months after the primary dislocation, whereas 21 patients, who were assessed after a median follow-up of 37 months (range 24-60 months), had not experienced a subsequent episode of lateral patellar instability. In all patients, age at the time of the primary dislocation, gender, the affected body side, body mass index, bilateral instability, physical activity according to Baecke's questionnaire, the grade of trochlear dysplasia, patellar height, tibial tuberosity-trochlear groove (TT-TG) distance, and patellar tilt were assessed. The odds ratio (OR) of each factor with regard to the patellar redislocation was calculated using contingency tables. Based on these data, a "patellar instability severity score" was calculated. RESULTS: The patellar instability severity score has six factors: age, bilateral instability, the severity of trochlear dysplasia, patella alta, TT-TG distance, and patellar tilt; the total possible score is seven. Reapplying this score to the study population revealed a median score of 4 points (range 2-7) for those patients with an early episode of patellar redislocation and a median score of 3 points (range 1-6) for those without a redislocation (p=0.0004). The OR for recurrent dislocations was 4.88 (95% CI 1.57-15.17) for the patients who scored 4 or more points when compared with the patients who scored 3 or fewer points (p=0.0064). CONCLUSION: Based on the individual patient data, the patellar instability severity score allows an initial risk assessment for experiencing a recurrent patellar dislocation and might help differentiate between responders and non-responders to conservative treatment after primary lateral patellar instability. LEVEL OF EVIDENCE: Case-control study, Level III.

Influence of tibial slope asymmetry on femoral rotation in patients with lateral patellar instability.

PURPOSE: The geometry of the tibial plateau and its influence on the biomechanics of the tibiofemoral joint has gained increased significance. However, no quantitative data are available regarding the inclination of the medial and lateral tibial slope in patients with patellar instability. It was therefore the purpose of this study to evaluate tibial slope characteristics in patients with patellar dislocations and to assess the biomechanical effect of medial-to-lateral tibial slope asymmetry on lateral patellar instability. METHODS: Medial and lateral tibial slope was measured on knee magnetic resonance images in 107 patients and in 83 controls. The medial-to-lateral tibial slope asymmetry was assessed as the intra-individual difference between the medial and lateral tibial plateau inclination considering severity of trochlear dysplasia. The effect of tibial slope asymmetry on femoral rotation was calculated by means of radian measure. RESULTS: Severity of trochlear dysplasia was significantly associated with an asymmetric inclination of the tibial plateau. Whereas the medial tibial slope showed identical values between controls and study patients (n.s.), lateral tibial plateau inclination becomes flatter with increasing severity of trochlear dysplasia (p < 0.01). Consequently, the intra-individual tibial slope asymmetry increased steadily (p < 0.01) and increased internal femoral rotation in 20° and 90° of knee flexion angles in patients with severe trochlear dysplasia (p < 0.01). In addition, the extreme values of internal femoral rotation were more pronounced in patients with patellar instability, whereas the extreme values of external femoral rotation were more pronounced in control subjects (p = 0.024). CONCLUSION: Data of this study indicate an association between tibial plateau configuration and internal femoral rotation in patients with lateral patellar instability and underlying trochlear dysplasia. Thereby, medial-to-lateral tibial slope asymmetry increased internal femoral rotation during knee flexion and therefore might aggravate the effect of femoral antetorsion in patients with patellar instability. LEVEL OF EVIDENCE: III.

Radiologically hyperdense zones of the patella seem to be partial osteonecroses subsequent to fracture treatment.

The blood supply to the proximal patella is provided primarily via intraosseous vessels from the inferior patella. Two vascular systems within the patella are distinguished: Tiny arteries penetrate the middle third of the anterior patellar surface via vascular foramina and continue in a proximal direction. Additional vessels enter the patella at its distal pole, between the patellar ligament and the articular surface, and also run proximally. As a result of the double vascular supply to the distal portion and the vulnerable blood supply to the proximal part, localized osteonecroses subsequent to fracture may occur within the patella and nearly exclusively affect the upper portion of the patella. Such focal regions of osteonecrosis may appear radiographically as localized regions of hyperdensity within the patella. The aim of this study was to investigate the extent to which radiologically hyperdense areas, possibly representing localized osteonecrosis, may occur subsequent to surgical treatment of a patella fracture and the influence that they have on the outcome of the fracture. Retrospective analysis of 100 patients who had been treated operatively for a patella fracture from January 1998 to December 2008 was conducted. The subjective pain rating, clinical scores, and patient satisfaction scores were recorded. Existing X-rays were assessed with regard to possible increased radiological dense areas. After an average of 60.61 ( ± 33.88) months, it was possible to perform a clinical follow-up on 60 patients aged 45.48 ( ± 18.51) years. Radiographic follow-up of all patients revealed that nine patients (9%) exhibited a hyperdense area in the proximal patella portion. X-rays showed radiopaque areas between 1 and 2 months after surgery. In seven cases, the radiological finding disappeared after six months. In two patients with persisting radiologically dense areas, bone necrosis was verified by means of magnetic resonance imaging (MRI) examination and a histological assessment, respectively. The clinical outcome of these patients with a hyperdense area on the patella, in this small series, was not shown to be worse than those who demonstrated normal healing. Radiologically hyperdense areas subsequent to patella fracture may represent partial osteonecrosis caused by localized vascular compromise. This was confirmed by MRI and histological examinations in two patients with persistent hyperdense lesions. The clinical outcome of patients with hyperdense zones seems to be poorer than that of patients without such findings, but no statistical difference was shown in this small series. It is possible that earlier surgical treatment and thus a shorter ischemic period as well as tissue-conserving operative techniques could prevent the occurrence of partial necroses. This hypothesis would require further study.

MRI but not arthroscopy accurately diagnoses femoral MPFL injury in first-time patellar dislocations.

PURPOSE: The purpose of this study was to investigate whether the femoral part of the medial patellofemoral ligament (MPFL) and its injury can be accurately assessed by standard knee arthroscopy in first-time patellar dislocations or whether preoperative MRI is required to determine injury location in patients where primary MPFL repair is attempted. METHODS: Twelve patients with acute first-time dislocations and MRI-based injury of the femoral MPFL and ten patients with recurrent patellar dislocations underwent knee arthroscopy with the use of a 30-degree optic and standard antero-medial and antero-lateral portals. The femoral origin was marked with a cannula under lateral fluoroscopy. Arthroscopic findings of the location of the native femoral MPFL and its injury were compared to the results of MRI and mini-open exploration. RESULTS: In acute cases, the average time from primary patellar dislocation to MRI evaluation was 3 days (1-9 days), and the average time from MRI to surgery was 8 days (3-20 days). The native femoral origin of the MPFL was not visible in any of the chronic cases during arthroscopy. In addition, in all acute cases, arthroscopy failed to directly visualize injury of the femoral MPFL (0 of 12), but mini-open exploration confirmed injury in 11 of 12 patients. This means that arthroscopy was less accurate than MRI for the diagnosis of femoral MPFL injury (P < 0.05). CONCLUSION: The results of this study indicate the limitations of knee arthroscopy in identifying the femoral disruption of the MPFL, a crucial injury that occurs in patellar dislocations. Thus, if a primary MPFL repair is planned, determination of the site of repair should be based on the preoperative MRI. LEVEL OF EVIDENCE: Diagnostic study of non-consecutive patients, Level III.

Interleukin-7 levels in synovial fluid increase with age and MMP-1 levels decrease with progression of osteoarthritis.

BACKGROUND AND PURPOSE: Little is known about biochemical mediators that correlate with the initiation and progression of knee osteoarthritis (OA). We therefore valuated the roles of cytokines and metalloenzymes in knee OA in relation to OA grading, age, and BMI. PATIENTS AND METHODS: A multiplex ELISA-based immunoassay (Luminex technology) was used to measure biochemical mediators in the synovial fluid (SF) of 82 patients undergoing knee surgery. All patients were classified according to age, BMI, and OA grade. 24 patients had no signs of OA (knee reconstruction surgeries). The mediators that were tested for included interleukins (IL-1Ra, IL-6, IL-7, and IL-18), chemokines (CCL2 (MCP-1), CCL3 (MIP-1a), and CXCL8 (IL-8)), growth factors (HGF and VEGF), and matrix metalloproteinases (MMP-1, MMP-2, MMP-9, and MMP-13). RESULTS: There was a correlation between IL-7 levels in SF and age (p < 0.01). The 11 highest IL-7 levels were seen in patients who were aged between 59 and 72 but had different OA grades. In contrast, all patients who had severe OA in all 3 knee compartments (pan-OA) had only low or medium IL-7 levels. There was a negative correlation between MMP-1 levels in synovial fluid and grade of OA (p < 0.001). Correlation studies between pairs of mediators revealed two groups of mediators that are important in OA progression, dominated by MCP-1 and IL-1Ra. INTERPRETATION: IL-7 levels in SF are elevated in elderly people suffering from OA of different grades, but they are depressed in patients with severe 3-compartment OA, possibly due to widely impaired chondrocytes embedded in the affected cartilage tissue. The observed decrease in MMP-1 levels in SF, which is dependent on the severity of OA, may be caused by deterioration of superficial cartilage layers during progression of OA.

["Surgical intermediate care unit" outcomes, facts and experiences after 5 years]. / "Interdisziplinäre Chirurgische Intermediate Care-Station" Erfahrungen nach 5 Jahren.

The increasing economic pressure has resulted in strategies to use efficient treatment forms. The aim of our study was to evaluate to which extent the intermediate care unit (IMC-unit) relieves the intensive care unit and the wards. We analyzed: patient population, age, gender, admission criteria and the rate of patients with intensive nursing procedures between January 1, 2005 and December 31, 2007. The level of care was calculated according to the standard patient categories. The mean age amounted to 58.9 years. Intensive care patients made up 43.6% and patients from the emergency ward 36.6% of the total IMC-allocation. After IMC care 54.3% of all IMC-patients could be taken over by wards. The confused patients amounted to 27.5% and isolated patients 4.3%. The average care intensity amounted to 4.5 hours per patient daily and the mean length of stay in hospital was 9 days. Particularly the relief of nursing intensity and the possibility of primary treatment of severely injured persons reflect the requirements of IMC.

Influence of platelet-rich plasma on chondrogenic differentiation and proliferation of chondrocytes and mesenchymal stem cells.

BACKGROUND/AIMS: Autologous chondrocyte (CC) transplantation has the disadvantages of requiring two surgical interventions and in vitro expansion of cells, implying the risk of cellular dedifferentiation. Our clinical aim is to develop a one-step procedure for autologous CC transplantation, i.e. harvesting, isolation and reimplantation of CC performed in one single surgical procedure. Platelet-rich plasma (PRP) is a source of autologous growth factors reported to have mitogenic effects. The objective of this study was to test the influence of PRP as an autologous scaffold on freshly isolated CC and mesenchymal stem cells (MSC). METHODS: CC and MSC were subjected to two- or three-dimensional (3D) growth systems, either with or without PRP. Chondrogenic differentiation was determined via quantification of collagen type II mRNA and immunohistochemical staining. RESULTS: We observed a proliferative effect for MSCs exposed to PRP in monolayer culture and an increase in the expression of chondrogenic markers when cells are exposed to a 3D environment. CCs exposed to PRP show a decrease in the chondrogenic phenotype with increasing proliferative activity. CONCLUSION: PRP has a proliferative effect on CCs and MSCs. In a one-step procedure for autologous CC transplantation, this might be an advantage over other scaffold materials, but confirmation in in vivo studies is required.

Quantified contours of curvature in female index, middle, ring, and small metacarpophalangeal joints.

PURPOSE: To study and quantify the morphology of the curvature of the surfaces of metacarpophalangeal metacarpophalangeal joints and to relate joint morphology to joint function. METHODS: Forty metacarpophalangeal joints of the index, middle, ring, and small fingers from 5 right and 5 left hands were taken from female cadavers. The articulating surfaces of the metacarpal head and the base of the proximal phalanx were copied in a true-to-scale fashion. The hard plaster models were sliced in 7 sagittal and 7 transverse planes. The curvatures of the section contours were determined with circular gauges. Statistical analyses were performed by analysis of variance and paired Student t-tests. RESULTS: In the sagittal plane, the cartilaginous surface of the metacarpal head is divided into 2 functional regions and a third dorsal region that does not articulate with the base of the proximal phalanx. The articulating surface of the base of the proximal phalanx approximates a circle in the midsagittal plane. The mean median sagittal radius of curvature of the dorsal articulating aspect of the metacarpal head (6.9 mm) is 33% smaller than that of the base of the proximal phalanx (10.3 mm). The palmar articulating aspect of the metacarpal head (5.8 mm) is 44% smaller than that of the base of the proximal phalanx (10.3 mm). In the median transverse section, the mean radius of curvature of the metacarpal head (7.3 mm) is 18% smaller than that of the base of the proximal phalanx (8.9 mm). CONCLUSIONS: The data demonstrate the highly significant incongruity in the curvature of the articulating pair. This incongruity provides a joint space with its greatest dimension in the sagittal plane. From a mechanical perspective, the metacarpophalangeal joint mechanically represents a joint with 5 kinematic degrees of freedom: 2 for flexion and extension, 2 for abduction and adduction, and 1 for axial rotation.

Delayed cyclops syndrome: symptomatic extension block four years after anterior cruciate ligament reconstruction.

Loss of knee extension after reconstruction of the anterior cruciate ligament may occur due to a neoproliferative fibrous nodule located anterolateral to the tibial tunnel, termed cyclops syndrome. This nodule occurs usually within the early postoperative period and results in diminished knee extension due to impingement on the intercondylar notch. We report a case of a 24-year-old female patient with an uncommon delayed-onset loss of knee extension due to a cyclops syndrome four years after anterior cruciate ligament reconstruction.

Real-time assessment of hepatic function is related to clinical outcome in critically ill patients after polytrauma.

OBJECTIVES: The aim was to investigate the outcome MODS/MOF in critically ill patients with regard to early hepatic dysfunction. METHODS: Thirty adult polytrauma patients admitted to the ICU, with ISS >or=16 were prospectively investigated. Real-time liver function was assessed using the MEGX test and arterial ketone body ratio (AKBR) 12-24 h after admittance to ICU, and on days 3, 5, 8, 12. RESULTS: Six patients (19%) died between days 4 and 29. Non-survivors were older (64.2 vs. 31.5 years), had a significantly higher ISS (40.5 vs. 30; p=0.002) and MODS score (9.5 vs. 5; p=0.001) on admittance to the ICU than survivors. On day 3 MEGX values (31 vs. 71.3 microg/L; p=0.001) and the AKBRs (0.6 vs. 1.3; p=0.001) were significantly lower in non-survivors than in survivors whereas IL-6 levels were significantly higher in the former group (519 vs. 61 microg/L; p=0.05). CONCLUSIONS: The MEGX test and AKBR are sensitive early indicators of hepatic dysfunction in severely injured polytrauma patients at risk for developing MODS/MOF.

Prognostic reliability of the Hawkins sign in fractures of the talus.

OBJECTIVE: To determine the prognostic reliability, sensitivity, and specificity of the Hawkins sign. The Hawkins sign is a subchondral radiolucent band in the talar dome that is indicative of viability at 6 to 8 weeks after a talus fracture. It is visible in the anterior-posterior view, but seldom appears on lateral radiographs. DESIGN: Retrospective study. SETTING: University hospital. PATIENTS AND METHODS: Between January 1995 and December 2000, a total of 41 patients (13 female, 28 male) with displaced talar fractures were operated on in our hospital. Thirty-four patients with a mean age of 35 years (range 12-60) were followed for more than 36 months (range 36-52). The prognostic reliability of the Hawkins sign was studied in 31 of these patients using a two-by-two table. The Ankle-Hindfoot scale of the American Orthopaedic Foot and Ankle Society (AOFAS) was used as an outcome measure. RESULTS: No Hawkins sign was found in the five patients who developed avascular necrosis (AVN) of the talus. In the remaining 26 patients who did not develop AVN, a positive (full) Hawkins sign was observed 11 times, a partially positive Hawkins sign 4 times, and a negative Hawkins sign 11 times. The Hawkins sign thus showed a sensitivity of 100% and a specificity of 57.7%. The Hawkins sign (if present) appeared between the 6th and the 9th week after trauma. Mean [range] AOFAS scores were: Pain, 31 [10-40] out of 40; Function, 39 [14-50] out of 50; and Alignment, 7 [0-10] out of 10. The clinical results were satisfactory. CONCLUSION: The Hawkins sign is a good indicator of talus vascularity following fracture. If a full or partial positive Hawkins sign is detected, it is unlikely that AVN will develop at a later stage after injury.

German validation of Quality of Life after Brain Injury (QOLIBRI) assessment and associated factors.

The consequences of traumatic brain injury (TBI) for health-related quality of life (HRQoL) are still poorly understood, and no TBI-specific instrument has hitherto been available. This paper describes in detail the psychometrics and validity of the German version of an internationally developed, self-rated HRQoL tool after TBI-the QOLIBRI (Quality of Life after Brain Injury). Factors associated with HRQoL, such as the impact of cognitive status and awareness, are specifically reported. One-hundred seventy-two participants after TBI were recruited from the records of acute clinics, most of whom having a Glasgow Coma Scale (GCS) 24-hour worst score and a Glasgow Outcome Scale (GOSE) score. Participants had severe (24%), moderate (11%) and mild (56%) injuries as assessed on the GCS, 3 months to 15 years post-injury. The QOLIBRI uses 37 items to measure "satisfaction" in the areas of "Cognition", "Self", "Daily Life and Autonomy", and "Social Relationships", and "feeling bothered" by "Emotions"and "Physical Problems". The scales meet standard psychometric criteria (α = .84 to .96; intra-class correlation-ICC = .72 to .91). ICCs (0.68 to 0.90) and αs (.83 to .96) were also good in a subgroup of participants with lower cognitive performance. The six-subscale structure of the international sample was reproduced for the German version using confirmatory factor analyses and Rasch analysis. Scale validity was supported by systematic relationships observed between the QOLIBRI and the GOSE, Patient Competency Rating Scale for Neurorehabilitation (PCRS-NR), Hospital Anxiety and Depression Scale (HADS), Profile of Mood States (POMS), Short Form 36 (SF-36), and Satisfaction with Life Scale (SWLS). The German QOLIBRI contains novel information not provided by other currently available measures and has good psychometric criteria. It is potentially useful for clinicians and researchers, in post-acute and rehabilitation studies, on a group and individual level.

Growth behavior, matrix production, and gene expression of human osteoblasts in defined cylindrical titanium channels.

The purpose of the current study was to investigate the effect of different diameters of cylindrical titanium channels on human osteoblasts. Titanium samples having continuous drill channels with diameters of 300, 400, 500, 600, and 1000 microm were put into osteoblast cell cultures that were isolated from 12 adult human trauma patients. Cell migration into the drill channels was investigated by transmitted-light microscopy. The DNA content in the drill channels was measured photometrically, collagen type I production was analyzed by enzyme-linked immunosorbent assay (ELISA) and osteocalcin gene expression by reverse transcriptase-polymerase chain reaction (RT-PCR). Formation of mineralized tissue was assessed by microradiographs of histological sections. Within 20 days, cells grew an average of 838 microm (+/-128 microm) into the drill channels with a diameter of 600 microm and were significantly faster (p < 0.05) than in all other channels. Cells produced significantly more osteocalcin messenger RNA (mRNA) in 600-microm channels (p < 0.05) than they did in 1000-microm channels and demonstrated the highest osteogenic differentiation. The channel diameter did not influence collagen type I production. The highest cell density was found in 300-microm channels (p < 0.05). The DNA content of the channels linearly decreased with increasing channel diameters. After 40 days of culture, the proportion of mineralized tissue at the mouth section amounted to 6% in 300-microm channels and to 9-11% in 400-600-microm channels. In 1000-microm channels, only traces of mineralization were detected. Our data suggest that the diameter of cylindrical titanium channels has a significant effect on migration, gene expression, and mineralization of human osteoblasts.

Vastus medialis obliquus muscle morphology in primary and recurrent lateral patellar instability.

The morphology of the vastus medialis obliquus (VMO) muscle in the anatomical setting of an unstable patella has not been described. Therefore, the purpose of this study was to investigate the morphological parameters of the VMO muscle that delineate its importance in the maintenance of patellofemoral joint stability. Eighty-two consecutive subjects were prospectively enrolled in this study. The groups were composed of thirty patients with an acute primary patellar dislocation, thirty patients with recurrent patellar dislocation, and twenty-two controls. Groups were adjusted according to sex, age, body mass index, and physical activity. Magnetic resonance imaging was used to measure the VMO cross-sectional area, muscle-fiber angulation, and the craniocaudal extent of the muscle in relation to the patella. No significant difference was found with respect to all measured VMO parameters between primary dislocation, recurrent dislocation, and control subjects with a trend noted for only the VMO cross-sectional area and the VMO muscle-fiber angulation. This finding is notable in that atrophy of the VMO has often been suggested to play an important role in the pathophysiology of an unstable patellofemoral joint.