Skeletal muscle fibers produce B-cell stimulatory factors in chronic myositis

Introduction

We aimed to identify B-cell-mediated immunomechanisms in inclusion body myositis (IBM) and polymyositis (PM) as part of the complex pathophysiology.

Materials and methods

Human primary myotube cultures were derived from orthopedic surgery. Diagnostic biopsy specimens from patients with IBM (n=9) and PM (n=9) were analyzed for markers of B cell activation (BAFF and APRIL) and for chemokines that control the recruitment of B cells (CXCL-12 and CXCL-13). Results were compared to biopsy specimens without myopathic changes (n=9) and hereditary muscular dystrophy (n=9).

Results

The mRNA expression of BAFF, APRIL, and CXCL-13 was significantly higher in IBM and PM compared to controls. Patients with IBM displayed the highest number of double positive muscle fibers for BAFF and CXCL-12 (48%) compared to PM (25%), muscular dystrophy (3%), and non-myopathic controls (0%). In vitro, exposure of human myotubes to pro-inflammatory cytokines led to a significant upregulation of BAFF and CXCL-12, but APRIL and CXCL-13 remained unchanged.

Conclusion

The results substantiate the hypothesis of an involvement of B cell-associated mechanisms in the pathophysiology of IBM and PM. Muscle fibers themselves seem to contribute to the recruitment of B cells and sustain inflammation.

[Refixation of osteochondral fragments with resorbable polylactid implants : Long-term clincal and MRI results]

BACKGROUND

Refixation with resorbable implants is a common surgical treatment in patients who suffer an injury with shearing of an osteochondral flake due to trauma of the knee or the upper ankle joint. To date there are no studies which outline long-term outcomes for this procedure. The aim of this study was to evaluate long-term clinical and magnetic resonance imaging (MRI) results after refixation with resorbable polylactide (PLLA) implants.

MATERIAL AND METHODS

In this retrospective study 12 patients with 13 injuries were examined 13.9 years (±1.2 years) after refixation of an osteochondral fragment of the knee (10 patients) and the upper ankle joint (2 patients) with a mean size of 3.33 cm² (±2.33) by resorbable polylactide (PLLA) implants (nails, pins, screws, Bionx, Tampere, Finland). To objectify the clinical results eight established clinical scores (VASS, Tegner, Lysholm, McDermott, KSS, WOMAC, AOFAS, FADI+Sports) were used. Furthermore, the morphological integration of bone and cartilage was assessed by MRI (3 T) using proton-weighted and cartilage-sensitive 3D double-echo steady-state (DESS) sequences. The morphological results were objectified with a modified MRI score according to Henderson et al.

RESULTS

After 13.9 years (±1.2) the patients with an injury of the knee as well as of the upper ankle joint showed good to excellent results (knee: VASS 1.2 (±1.7), Tegner 4.4 (±1.3), Lysholm 85.7 (±12.2), McDermott 90.7 (±8.6), KSS 189 (±14.2), WOMAC (6.16% (±8.45)) (upper ankle joint: VASS 2.5 (±2.5), Tegner 5.5 (±1.5), Lysholm 87 (±13), McDermott 88 (±12); WOMAC (8.54% (±8.54), AOFAS 75.5 (±24.5), FADI+Sports 118 (±18)). In all cases there was evidence of good integration of the osteochondral fragment in MRI. In five patients there was moderate subchondral cyst formation (∅ ≤1 mm); however, mild changes of the cartilage contour were found in all patients. The mean modified Henderson score achieved was 14.4 (±2.0, best 8, worst 32), which corresponds to a good morphological result.

CONCLUSION

Because of good clinical and morphological results shown by MRI, refixation through resorbable implants (PLLA) can be recommended for treatment of traumatic osteochondral flakes.

The thumb carpometacarpal joint: curvature morphology of the articulating surfaces, mathematical description and mechanical functioning

PURPOSE

The purpose is to present a mathematical model of the function of the thumb carpometacarpal joint (TCMCJ) based on measurements of human joints. In the TCMCJ both articulating surfaces are saddle-shaped. The aim was to geometrically survey the shapes of the articulating surfaces using precise replicas of 28 TCMCJs.

METHODS

None of these 56 articulating surfaces did mathematically extend the differential geometrical neighbourhood around the main saddle point so that each surface could be characterised by three main parameters: the two extreme radii of curvature in the main saddle point and the angle between the saddles' asymptotics (straight lines).

RESULTS

The articulating surfaces, when contacting at the respective main saddle points, are incongruent. Hence, the TCMCJ has functionally five kinematical degrees of freedom (DOF); two DOF belong to flexion/extension, two to ab-/adduction. These four DOF are controlled by the muscular apparatus. The fifth DOF, axial rotation, cannot be adjusted but stabilized by the muscular apparatus so that physiologically under compressive load axial rotation does not exceed an angle of approximately ±3°.

CONCLUSIONS

The TCMCJ can be stimulated by the muscular apparatus to circumduct. The mechanisms are traced back to the curvature incongruity of the saddle surfaces. Hence we mathematically proved that none of the individual saddle surfaces can be described by a quadratic saddle surface as is often assumed in literature. We derived an algebraic formula with which the articulating surfaces in the TCMCJ can be quantitatively described. This formula can be used to shape the articulating surfaces in physiologically equivalent TCMCJ-prostheses.

The morphology of the articular surfaces of biological knee joints provides essential guidance for the construction of functional knee endoprostheses

PURPOSE

In comparative examinations of kinematics of the knees of humans and pigs in flexional/extensional motion under compressive loads, the significant differential geometric essentials of articular guidance are elaborated to criticise the shaping of the articular surfaces of conventional knee-endoprostheses and to suggest constructional outlines that allow the endoprosthesis to adopt natural knee kinematics. Implantation is discussed with regard to the remaining ligamentous apparatus.

METHODS

Twelve fresh pig knee joints and 19 preserved human knee joints were moved into several flexional/extensional positions. In each joint, the tibia and femur were repeatably caught by metal plates. After removing all ligaments, the tibia and femur were again caught in these positions, and their points of contact were marked on both articular surfaces. Along the marker points, a thin lead wire was glued onto each surface. The positions and shapes of the four contact lines were mapped by teleradiography.

RESULTS

All contact lines were found to be plane curves. The medial and lateral planes were parallel, thus defining the joint's sagittal plane. In the human knee, as compared to the lateral, the medial femoral contact line was always shifted anteriorly by several millimetres. The tibial contact curve was laterally convex and medially concave. In the pig knees, the lateral and medial contact lines were asymmetrically placed. Both tibial curves were convex.

CONCLUSIONS

Both knees represent cam mechanisms (with one degree of freedom) that produce rolling of the articular surfaces during the stance phase. Implantation requires preservation of the anterior cruciate ligament, and ligamentous balancing is disadvantageous.

Navigated cementless total knee arthroplasty - medium-term clinical and radiological results

Purpose:

The objective of this prospective study was to evaluate the medium-term clinical and radiological results after navigated cementless implantation, without patella resurfacing, of a total knee endoprosthesis with tibial and femoral press-fit components, with a focus on survival rate and clinical outcome. The innovation is the non-cemented fixation together with the use of a navigation system.

Scope and Methods:

Sixty patients with gonarthrosis were included consecutively in this study. In all cases, the cementless Columbus total knee endoprosthesis with a coating out of pure titanium was implanted, using a navigation system. The Knee Society Score showed a statistically significant increase from 75 (± 21.26) before surgery to 180 (± 16.15) after a mean follow-up of 5.6 (± 0.25) years. The last radiological examination revealed no osteolysis. No radiolucent lines were seen at any time in the area of the femoral prosthetic components. In the tibial area, radiolucent lines were seen in 24.4 % of the cases, mostly in the distal uncoated part of the stem. During follow-up, no prosthesis had to be replaced because of aseptic loosening while in 2 cases revision surgery was necessary due to septic loosening and in 1 case due to unexplainable pain.

Results and Conclusions:

Navigated cementless implantation of the Columbus total knee endoprosthesis yielded good clinical and radiological results in the medium term. The excellent radiological osteointegration of the prosthetic components, coated with a microporous pure titanium layer and implanted with a press-fit technique, should be emphasized.

Bioabsorbable interference screw versus bioabsorbable cross pins: influence of femoral graft fixation on the clinical outcome after ACL reconstruction

PURPOSE

The aim of this study was to evaluate the clinical outcome and differences in anterior–posterior laxity of ACL reconstruction using a bioabsorbable interference screw for femoral graft fixation when compared to femoral bioabsorbable cross pin fixation.

METHODS

Clinical outcome was evaluated among 59 patients 1 year after arthroscopic ACL reconstruction with hamstrings graft in a prospective, non-randomised study. In 31 cases, femoral fixation of the graft was performed using a bioabsorbable interference screw. In 28 cases, two bioabsorbable cross pins were used for femoral fixation. Patients were evaluated using Tegner, Lysholm and Marshall scores, the visual analogue scale for pain and KT-1000 arthrometer measurement.

RESULTS

No significant difference (P ≥ 0.05) was observed at follow-up for the knee scores. The average Tegner score was 5.83 points (±2.00) for the interference screw fixation and 5.83 points (±1.24) for the cross pin fixation; the average Lysholm score was 93.58 (±5.79) to 92.72 (±6.34) points; and the average Marshall score 46.72 (±2.4) to 47.30 (±2.35) points. No significant difference was found for the visual analogue scale for pain. KT-1000 arthrometer measurement revealed a significant (P < 0.05) difference in the mean side-to-side anterior translation at all applied forces. At 67 N, the mean difference was 1.53 mm (±1.24) in the interference screw group and 0.47 mm (±1.18) in the cross pin group (P < 0.05). At 89 N, the mean differences were 1.85 mm (±1.29) versus 0.59 mm (±1.59), respectively, (P < 0.05), and maximum manual displacements were 2.02 mm (±1.26) versus 1.22 mm (1.18; P < 0.05).

CONCLUSIONS

In ACL reconstruction with hamstrings graft, similar clinical results are obtained for the use of bioabsorbable cross pins when compared to bioabsorbable interference screws for femoral fixation. Cross pin fixation was superior with regard to the anteroposterior laxity as measured with KT-1000.

[The treatment of patellar dislocation: a systematic review]

AIM

The diagnosis and treatment of patellar dislocation is very complex. The aim of this study is to give an overview of the biomechanics of the patellofemoral joint and to point out the latest developments in diagnosis and treatment of patellar dislocation.

METHOD

The authors electronically searched Medline, Cochrane and Embase for studies on the biomechanics of the patellofemoral joint and for conservative and surgical treatments after patellar dislocation. We extracted baseline demographics, biomechanical, conservation and surgical details.

RESULTS

Understanding the biomechanics of the patellofemoral joint is necessary to understand the pathology of patellar dislocation. The patellofemoral joint consists of a complex system of static, active and passive stabilising factors. Patellar instability can result from osseous and soft-tissue abnormalities, such as trochlear dysplasia, patella alta, a high tibial tuberosity trochlear groove (TTTG) distance, weaknesses of the vastus medialis obliquus or a lesion of the medial retinaculum. Recent studies have focused on the medial patellofemoral ligament (MPFL) and have shown that the MPFL is the most significant passive stabiliser of the patella. Following patellar dislocation, an MRI should be standard practice to detect an MPFL rupture, osteochondral lesions or other risk factors for redislocation. An acute first-time patellar dislocation without osteochondral lesions and without severe risk factors for a redislocation should follow a conservative treatment plan. If surgical treatment is required, the best postoperative results occur when the MPFL is reconstructed, leading to a redislocation rate of 5%, this includes cases that have a dysplastic trochlea. Duplication of the medial retinaculum show very inconsistent results in the literature, possibly due to the fact that the essential pathomorphology of patellar dislocation is not addressed. Addressing the exact location of the rupture of the MPFL with a suture is possibly more convenient, especially after first-time dislocation with associated risk factors for a redislocation. Recent literature does not encourage the use of lateral release, since this can increase patellar instability. Indications for lateral release include persistent patellar instability or pain reduction in an older arthritic subject. For correcting a patellofemoral malalignment, the TTTG distance should be measured and a medial transposition of the anterior tibial tubercle hinged on a distal periosteal attachment should be considered. Cartilage lesions on the medial facet of the patella are a contra-indication for medial tubercle transposition. For cartilage lesions of the lateral facet, antero-medialization of the tibial tubercle can be successful. A tubercle osteotomy can be efficiently combined with MPFL reconstruction. We believe that patients with open epiphyseal plates should be treated with duplication of the medial retinaculum. In the presence of patellar maltracking, an additional subperiostal soft tissue release with medialisation of the distal part of the patellar tendon can be performed.

CONCLUSION

It seems that the predominating factors for patellar dislocation are heterogenic morphology in combination with individual predisposition. Non-surgical treatment is typically recommended for primary patellar dislocation without any osteochondral lesions and in the absence of significant risk factors for redislocation. If surgical treatment is deemed necessary, addressing the essential pathomorphology has become the primary focus.

Patellar dislocations in children, adolescents and adults: a comparative MRI study of medial patellofemoral ligament injury patterns and trochlear groove anatomy

PURPOSE

The first aim was to compare medial patellofemoral ligament injury patterns in children and adolescents after first-time lateral patellar dislocations with the injury patterns in adults. The second aim was to evaluate the trochlear groove anatomy at different developmental stages of the growing knee joint.

MATERIALS AND METHODS

Knee magnetic resonance (MR) images were collected from 22 patients after first-time patellar dislocations. The patients were aged 14.2 years (a range of 11-15 years). The injury pattern of the medial patellofemoral ligament was analysed, and trochlear dysplasia was evaluated with regard to sulcus angle, trochlear depth and trochlear asymmetry. The control data consisted of MR images from 21 adult patients who were treated for first-time lateral patellar dislocation.

RESULTS

After patellar dislocation, injury to the medial patellofemoral ligament was found in 90.2% of the children and in 100% of the adult patients. Injury patterns of the medial patellofemoral ligament were similar between the study group and the control group with regard to injury at the patellar attachment site (Type I), to the midsubstance (Type II) and to injury at the femoral origin (Type III) (all p>0.05). Combined lesions (Type IV) were significantly less frequently observed in adults when compared to the study group (p=0.02). The magnitude of trochlear dysplasia was similar in children, adolescents and adults with regard to all three of the measured parameter-values (all p>0.05). In addition, the articular cartilage had a significant effect on the distal femur geometry in both paediatrics and adults.

CONCLUSION

First, the data from our study indicated that the paediatric medial patellofemoral ligament injury patterns, as seen on MR images, were similar to those in adults. Second, the trochlear groove anatomy and the magnitude of trochlear dysplasia, respectively, did not differ between adults and paediatrics with patellar instability. Thus, physicians are confronted with similar anatomical risk factors and similar injuries to the medial soft-tissue restraints in children when compared to adults with patellar instability.

Axial rotation in the lumbar spine following axial force wrench

The report presents measurements of axial rotation of lumbar motion segments (L1/L2, L3/L4, L4/L5), particularly with small angles of rotation (in the range of +/-1 degrees) following axial force wrenches. The investigation focussed on determining the influence of geometrically varying configurations in axial wrench (consisting of axial torque and axial force) applied on the kinematics (as defined by the migrating instantaneous helical axis, IHA) of lumbar motion segments under constant resulting axial force, and relating IHA-migration to anatomical structures. In all segments, IHA migrated over several centimetres (up to 6 cm). The main portion of IHA-migration was linked to the angle of rotation interval of +/-1 degrees. 3. The shape of the IHA-migration was greatly dependent upon the position of the force line F(z). The-force-wrench-dependent wide IHA-migration found for the rotational angle interval of +/-1 degrees suggests that joint guidance predominates in segment kinematics. The segment kinematics can be adjusted by means of the geometrical configuration of the force wrenches. The design of non-fusion spine implants and FE calculations have to take into consideration joint guidance and muscular force distributions with small intervals of axial rotation.

Knee motion analysis of the non-loaded and loaded knee: a re-look at rolling and sliding

Many studies of knee motion have been reported in the literature over more than 100 years. Of particular interest to the analysis presented here is the work of the Freeman group, who elegantly measured tibio-femoral kinematics in studies made on cadavers and the knees of living individuals using MRI, anatomical dissection and RSA. We examined and re-evaluated the data collected by Freeman's group and suggest that their conclusion should be considered to be incorrect, since their methods of evaluation were oversimplified from the mathematical and physical perspectives. By applying appropriate methods, however, it is possible to show that the same data yield important insights into physiological knee kinematics and reveal that the rolling-sliding relationship depends on the degree of flexion and on joint load in the medial and lateral compartment, as well. In the initial range of flexion, a considerable amount of rolling was found to occur. Based on this analysis, it is possible to gain useful insights of value for the design of total knee replacements.

Mechanisms of circumduction and axial rotation of the carpometacarpal joint of the thumb

Osteoarthritis of the carpometacarpal joint of the thumb (CMCJ) is a frequent clinical problem. The aim of the study was to discuss the mechanisms of circumduction and axial rotation of the CMCJ considering geometrical properties of the articulating surfaces and the configuration of the muscle system acting over the CMCJ. 28 CMCJ from 7 female and 7 male corpses (age: 81 yrs (median), 53-91 yrs (interval), which did not show any sign of arthrosis, were investigated. Contours in flexion/extension: in saddle point O, the contour of the proximal surface is stronger curved. For 23 of the 28 joints the contours showed an eye-catching difference. Contours in ab-/adduction: all 28 joints showed the respective incongruity. Straight lines and their included angles: in both articulating surfaces, the angles between the straight lines through the saddle point showed values which were close to 90 degrees. Out of neutral position a small axial rotation (maximal range: 3.5 degrees) is possible without that the contact at the saddle points is changed. But, when one of the straight lines of the proximal surface meets a respective straight line of the distal surface, the contact "point" is enlarged to a contact "line". When the axial rotation is further increased, the contact "line" splits into two contacts "points", which are located at outer areas of the articulating surfaces.

How do spinal segments move?

PURPOSE

To study and clarify the kinematics of spinal segments following cyclic torques causing axial rotation (T(z) (t)), lateral-flexion (T(x) (t)), flexion/extension (T(y) (t)).

METHODS

A 6D--Measurement of location, alignment, and migration of the instantaneous helical axis (IHA) as a function of rotational angle in cervical, thoracic, and lumbar segments subjected to axially directed preloads.

RESULTS

IHA retained an almost constant alignment, but migrated along distinct centrodes. THORACIC SEGMENTS: IHA was almost parallel to T(z) (t), T(x) (t), or T(y) (t), stationary for T(x) (t) or T(y) (t), and migrating for T(z) (t) along dorsally opened bows. IHA locations hardly depended on the position or size of axial preload. LUMBAR SEGMENTS: IHA was also almost parallel to T(z) (t), T(x) (t), or T(y) (t). In axial rotation IHA-migration along wide, ventrally or dorsally bent bows depending on segmental flexional/extensional status. Distances covered: 20-60mm. In lateral-flexion: IHA-migration to the left/right joint and vice versa. In flexion/extension IHA-migration from the facets to the centre of the disc. CERVICAL SEGMENTS: In flexion/flexion IHA was almost stationary for and parallel to T(y) (t). In axial rotation or lateral-flexion IHA intersected T(z) (t)/T(x) (t) under approximately -30 degrees /+30 degrees.

CONCLUSIONS

Generally joints alternate in guidance. Lumbar segments: in axial rotation and lateral-flexion parametrical control of IHA-position and IHA-migration by axial preload position. Cervical segments: kinematical coupling between axial rotation and lateral-flexion. The IHA-migration guided by the joints should be taken into account in the design of non-fusion implants. FE-calculations of spinal mechanics and kinematics should be based on detailed data of curvature morphology of the articulating surfaces of the joint facets.

A novel total knee replacement by rolling articulating surfaces. In vivo functional measurements and tests

The purposes of the paper were as follows: to show the fundamental functional differences between the natural knee and common total knee replacements (TKR), to describe the ideas on how main properties of the natural knee can be adopted by a novel TKR and to present some main biomechanical functions of this TKR. By analyzing the morphology of the articulating surfaces and the kinematics of the natural knee the design of the novel TKR was developed. The use was made of the test procedures established in vitro and of lateral X-ray photographs as well as fluoroscopy in vivo. The function of the novel TKR is comparable to that of the natural knee joint in terms of kinematics (roll/slide behaviour), loads of the articulating surfaces (diminished shear loads), stability and leeway under external impacts, reduction of the load in the patellofemoral joint, and ligament balancing.

Wie sind die klinischen Ergebnisse operativ behandelter Talusfrakturen?

Our study focuses to determine the medium range results of function and radiological findings of operatively treated fractures of the talus. Furthermore we had the intention to investigate risk-factors for posttraumatic arthrosis and necrosis of the talus.

MATERIAL AND METHODS

We included all 41 patients (w/m: 13/28) operated between 1995-2000 with talus neck, corpus or dislocated fracture of the talus edge (open/closed: 11/30). Fractures were classified according to Hawkins: type 1: 6 x, type II: 17 x, type III: 7 x, type IV: 3 x, 8 x dislocated peripheral fractures. 39 x screw osteosynthesis, 2 x K-wire fixation were done and 12 additive transfixation with fixateur externe. Score: AOFAS Ankle-Hindfoot-Scale, radiological assessment according to the Bargon score. 34 patients, mean age 35 years (12-60), were followed up clinically with an average of 4 years (24-72 months).

RESULTS

AOFAS Score: pain (40 points): diameter 31 [10-40]; function (50 points): diameter 39 [14-50]; alignement (10 points):diameter 7 [0-10]; degree of arthritis due to the Bargon scale: 0 degree: 5x,1 degree: 8x, 2 degrees: 7 x, 3 degrees: 7 x.

COMPLICATIONS

4 x necrosis of margin of the wound, 1 deep infection, 5 necrosis of the talus bone. The severity of the fracture was 1 x type II according to Hawkins 3 x type III and 1 x type IV. 3 of the 5 patients who developed a talus necrosis had 28 or 38 soft tissue damage. One patient had an imminent compartment syndrome. One patient who suffered a polytrauma was operated six days post injury. Second operation: 1 Syme amputation due to necrosis of the talus subsequent to an infection. 4 x arthrodesis of the upper ankle joint and 5 x arthrodesis of the subtalar joint due to posttraumatic arthritis.

CONCLUSION

Primary screw osteosynthesis is the treatment of choice depending on the lesions of the soft-tissue and accompanied injuries in combination with a fixateur externe. Nevertheless the primary osteosynthesis is not able to prevent necrosis of the talus completely, that occurs in a frequency of 15%. Risk factors for a posttraumatic arthritis in addition to the type of fracture and the result of reconstruction are an accompanied soft tissue defect and local capsule-band complex with necessary temporary transfixation. Early plastic reconstruction of defects can reduce the time of immobilisation and allows motion therapy. The functional results are positive compared with the radiological results that showed arthritis in 70%.