Biomedical subjects

P M Rommens

Publications and source records attributed to P M Rommens.

At least 19 recordsLinked to original sources

PubMed2006

Locking plates for corrective osteotomy of malunited dorsally tilted distal radial fractures: a biomechanical study.

The purpose of the study was to compare the biomechanical properties of five different palmar fixation plate designs in a distal radius osteotomy cadaver model. A 1cm metaphyseal osteotomy gap was made to simulate a corrective osteotomy and the osteotomy plated. Axial load was applied to the distal end of each construct by a material testing machine under control of a motion analysis video system. The specimens were arranged into five implant groups of eight specimens each. No test group developed deformity and movement of the fracture gap greater than 2mm with a load of 100N. Increasing the load to 250N revealed statistically significant differences in stiffness and failure load between the different plates. Axial failure strength and stiffness were greater for the radial correction plates than for the other implants. The former may provide enough stability for corrective osteotomy of dorsally angulated distal radial malunions, even when the osteotomy gap is only filled with cancellous bone graft instead of cortical bone graft.

Aged↗

PubMed2006

[Shaft lengthening in hip replacement: experimental studies on bending stiffness].

BACKGROUND: Cortical atrophy of the proximal femur can be seen after wearing a total hip prosthesis for several years because loads are borne distally at the prosthesis tip. To achieve stable prosthesis implantation on the one hand and proximal bone regeneration on the other hand in hip revision arthroplasty, lengthening of the shaft component distributes loading forces to the femoral shaft first. It concentrates them to the proximal femur later through a higher elasticity. METHODS: In a three-point bending study the bending stiffness of an elastic slotted hip prosthesis shaft lengthening (HSL) was compared with that of the Synthes universal femoral nail (MN) and the unslotted HSL. RESULTS: The slotting of the elastic HSL has a significant influence on its bending stiffness; it lies 1,287 N/mm (76%) over that of the MN, but 1,855 N/mm (38%) under that of the unslotted HSL. Altogether the slotted HSL is rather more comparable to the MN than to the unslotted HSL regarding its bending conduct. CONCLUSION: The results confirm the elasticity of the slotted HSL in the style of conventional intramedullary nailing and encourage-above all in the context of previous clinical studies-its further use.

Biomechanical Phenomena↗

PubMed2006

[The cloverleaf plate for osteosythesis of humeral head fractures. Definition of the current position].

In this prospective study we evaluated the functional and radiological results obtained in 62 patients who had been treated for fracture of the humeral head by internal fixation with a cloverleaf plate. They were examined postoperatively, after 14 weeks and after an average follow-up of 75 weeks. Nine patients (14.5%) had dislocated 2-part fractures, 36 had 3-part fractures (58%; additional dislocations of the greater or lesser tubercle), 13 patients (21%) had 4-part fractures and 4 (5.6%) had luxation fractures of the humeral head. Early functional physiotherapy was started on the third day after surgery. The complications observed were: subcutaneous infection (2 cases; 3.2%), haematoma (2 cases; 3.2%), temporal paraesthesia of the axillary nerve (1 case; 1.6%). Only 4 (6.5%) patients suffered from necrosis of the humeral head (partial in 3, total in 1); in 2 cases (3.2%) we switched to a different procedure; in both these patients a humeral head prosthesis was implanted; in both these cases the clinical result was poor because of progressive varus dislocation. To improve mobility we performed arthrolysis in 8 cases (12.9%) and acromioplasty in 10 (16.1%), in addition to removing the plates after fracture consolidation confirmed by X-ray examination. In the present study those of our patients who had been treated with open reduction and internal fixation with a cloverleaf plate achieved average Neer scores of 77+/-13 and average Constant scores of 72.4+/-18, and the rates of complications or revisions were low. "Good" or "very good" results were obtained according to the Constant score in 59% of the treated patients. Even patients with complex 4-part fractures had average Constant scores of 72.7 points ("good"). The accuracy of the refixation of the greater tubercle, sufficiently low fixation of the cloverleaf plate and avoidance of varus position when the humeral head was repositioned were significant parameters influencing the functional outcome in our patients.

Adult↗

PubMed2005

The influence of bone allograft processing on osteoblast attachment and function.

In order to assess the influence of eight different sterilisation and disinfection methods for bone allografts on adhesion, proliferation, and differentiation of human bone marrow stromal cells (BMSC), cells were grown in culture and then plated onto pieces of human bone allografts. Following processing methods were tested: autoclavation (AUT), low-temperature-plasma sterilisation of demineralised allografts (D-LTP), ethylene oxide sterilisation (EtO), fresh frozen bone (FFB), 80 degrees C-thermodisinfection (80 degrees C), gamma-irradiation (Gamma), chemical solvent disinfection (CSD), and Barrycidal-disinfection (BAR). The seeding efficiency was determined after one hour to detect the number of attached cells before mitosis started. The cell viability was determined after 3, 7, and 21 days. Tests to confirm the osteoblastic differentiation included histochemical alkaline phosphatase staining and RT-PCR for osteocalcin. Human BMSC showed greatest attachment affinities for D-LTP-, 80 degrees C-, and CSD-allografts, whereas less cells were found attached to AUT-, EtO-, FFB-, Gamma-, and BAR-probes. Cell viability assays at day 3 revealed highest proliferation rates within the FFB- and 80 degrees C-groups, whereas after 21 days most viable cells were found in D-LTP-, 80 degrees C-, CSD-, and Gamma-groups. BAR-treatment showed a considerably toxic effect and therefore was excluded from all further experiments. Highest AP-activity and gene expression of osteocalcin were detected in the D-LTP-group in comparison with all other groups. In summary, our results demonstrate that cell adhesion, final population, and function of BMSC are influenced by different disinfection and sterilisation methods. Therefore, processing-related alterations of BMSC-function may be important for the success of bone grafting. The experimental setup used in the present work may be useful for further optimisation of bone allograft processing.

Alkaline Phosphatase↗

PubMed2005

[Internal fixation of proximal humerus fractures].

BACKGROUND: Intramedullary nails and angle-fixed plates have recently been used in proximal humerus fractures. Rigid implants might be associated with an increased risk of failure in osteoporotic conditions. METHODS: Unstable fractures of the surgical neck were created in 24 pairs of human humeri. The biomechanical properties of four implants were analysed. These were a nail with conventional interlocking (PHN-K), a nail with spiral blade interlocking (PHN-S), the T-plate, and an internal fixator with elastic screw properties (reference). The specimens were subjected to axial loading and torque. Stiffness, plastic deformity, and load to failure were assessed. RESULTS: The PHN-S was stiffer than the internal fixator. The PHN-K and T-plate were stiffer only during torque. Less subsidence was observed for the PHN-S. This implant failed at higher loads than the other implants. CONCLUSIONS: The PHN-S offers biomechanical advantages in unstable fractures of the surgical neck of the humerus. Elastic implant properties, however, are disadvantageous.

Aged↗

PubMed2005

["Progressive" hypothenar hammer syndrome Indication for operative treatment].

Hypothenar hammer syndrome (HHS) is ischemia of the distal ulnar artery caused by injury to the ulnar part of the palmar arch. This disease often involves workers who frequently use the hypothenar part of the hand as a hammer. The aneurysmatic form of HHS represents an indication for operative treatment; the thrombotic form is treated mainly conservatively. In our opinion, the symptomatic thrombotic form represents an indication for operation if symptoms persist during conservative therapy, particularly if symptoms progress. In fresh embolic occlusions, regional thrombolysis is usually successful. We present here the symptomatic treatment and course in two patients with complaints increasing during conservative therapy. The patients reported progressive Raynaud's phenomenon of the fingers. Angiography confirmed corkscrew-like aneurysmatic configuration of the distal ulnar artery and subsequent embolization of digital arteries. In both cases, we removed the source of the embolism with resection of the involved arterial segment and anastomosis with autologous vein grafts.

Adult↗

PubMed2005

[Complex pelvic trauma caused by an accidental side split].

Complex pelvic ring fractures are defined as injuries of the pelvic ring in association with lesions of the pelvic organs or the pelvic soft tissues. These injuries are typically caused by high-energy accidents. In contrast to the typical mechanism of injury a case is described in which a low energy trauma led to a complex pelvic ring trauma. An obese woman suffered an open-book injury of the pelvis with severe open urogenital soft-tissue damage by accidentally doing forced splits. Primary stabilization of the pelvic ring with external fixation and secondary internal fixation with a double-plate osteosynthesis of the symphysis led to a good clinical outcome concerning the osseous lesion. The urogenital injuries with rupture of the bladder, the urethra and the vagina led despite immediate urological management to an incontinence, which finally required definitive urine drainage via an ileum conduit.

Accidental Falls↗

PubMed2005

[MRT-induced burns in tattooed patients. Case report of an traumatic surgery patient].

Skin burns to patients with tattoos during MRI procedures are reported but rare complications. MRI scans are being used more often also as diagnostic procedures in trauma patients. In this article we present the case of a patient after trauma of the vertebral column who experienced burning pain at the site of a tattoo on the distal femur during the MRI examination, necessitating cessation of this procedure. Based on this example we discuss possible pathomechanisms of MRI-induced skin burns to patients with tattoos. It becomes clear that patients have to be asked about possible tattoos before MRI scans and should be informed about possible pain development.

Burns, Electric↗

PubMed2005

[Surgical treatment of type I capitellar-humeral fractures using the Henry ventral approach approach. Short- and medium-term results].

Capitellar fractures are rare. Despite adequate surgical treatment, patients suffer frequently from limited range of motion, osteonecrosis, and neurological deficits. The purpose of this retrospective study was to evaluate short- and medium-term surgical results in seven patients who had type I capitellar fractures according to Bryan and Morrey. All patients were treated via an anterior approach, according to Henry, and open reduction and internal fixation with two screws. Seven patients were examined clinically, neurologically, and radiologically after 10-65 months. The fracture healed in all patients. None of the patients had a neurological deficit. According to the Morrey Score, five of seven patients had an excellent or good functional result. Open reduction and internal fixation with two screws via the Henry approach is a suitable option for surgical treatment for type I capitellar fractures.

Adult↗

PubMed2005

[Operative strategies in the treatment of upper limb fractures in polytraumatized patients].

BACKGROUND: Optimal timing of operative treatment of upper extremity long bone fractures in polytraumatized patients depends on the type and location of the fractures, as well as on the cardiorespiratory stability of the patient, and should be early in diaphyseal fractures in order to optimize intensive care treatment. The timing of surgery in cases of upper limb fractures is secondary to life-saving therapies. The same applies to stabilization of fractures of the lower limbs, including fractures of the femur and tibial shaft. METHODS: The recommended operative procedure for adult polytraumatized patients with closed or open humeral shaft fractures of grade I or II is intramedullary nailing or plating. For closed or open lower arm fractures of grade I or II, plating is the best procedure, or alternatively nailing. For upper extremity epi- or metaphyseal fractures plating is preferred. Specific fracture situations require specific operative treatments, for example traction band for olecranon fractures, external fixation for distal radial multi-fragmentary fractures. The external fixator may be the optimal approach in grade III open fractures of the upper extremity long bones. The main difference in paediatric fractures is not the timing of the procedure, but the selection of the technique, which has to respect the epiphyseal growth plates. RESULTS: Additional vessel injuries require quick diagnosis and early vessel reconstruction in the presence of cardiopulmonary stability. Open fractures should have a higher therapeutic priority if they are associated with vessel/nerve lesions. The strategy in additional nerve injuries depends on the type of lesion. Nerve decompression should take place together with fracture stabilization; necessary nerve reconstruction should be performed secondarily. The primary phase should be limited to fracture fixation. If the fracture is combined with a compartment syndrome, decompression by fasciotomy together with fracture fixation ensuring cardiopulmonary stability has be performed. CONCLUSION: Amputations at the upper extremity in polytraumatized patients are only occasionally indicated in very severe injuries. In injuries involving total amputation, depending on the condition of the limb, immediate reattachment should be attempted if the cardiorespiratory situation of the patient is stable.

Arm Injuries↗

PubMed2004

Friction of ceramic and metal hip hemi-endoprostheses against cadaveric acetabula.

INTRODUCTION: Studies of hip arthroplasty have dealt mainly with total endoprosthesis, while tribology measurement values of hemi-endoprosthetic implants are rare. The small amount of experimental tribological data concerning materials of hemi-endoprosthetic implants in the form of pendulum trials, animal experiments, in vivo measurements on human hip joints and pin on disc studies report friction coefficients between 0.014 and 0.57; the friction coefficients measured in fresh human cadaver hip joints were determined between 0.001 and 0.08. MATERIALS AND METHODS: The HEPFlEx-hip simulator was constructed to test the friction coefficients of unipolar femur head hemi-endoprostheses made of metal or ceramic against fresh cadaveric acetabula. Its plane of movement is uniaxial with a flexion-extension movement of +30/-18 degrees . The force is produced pneumatically dynamic with amounts of 2.5 kN. Newborn calf serum serves as a lubricant. We mounted 20 fresh porcine acetabula and 10 fresh human cadaver acetabula in the HEPFlEx-hip simulator and compared the two unipolar femur head hemi-endoprostheses (metal vs. ceramic). RESULTS: The mean friction coefficients against porcine acetabula were micro=0.017-0.082 for ceramic and micro=0.020-0.101 for metal; against human cadaver acetabula micro=0.017-0.083 for ceramic and micro=0.019-0.118 for metal. The frictional coefficient deltas (metal-ceramic) values of all measurements were Deltamicro=0.004 for porcine acetabula and Deltamicro=0.001 for cadaver acetabula. Box-plots graphics document significantly lower frictional coefficients of the ceramics. CONCLUSIONS: The lower frictional coefficients of ceramic compared to metal against fresh cadaveric acetabula may have a clinical impact on the process of the protrusion of the corresponding femoral head through the acetabulum.

Acetabulum↗

PubMed2004

[Intramedullary osteosynthesis of the ulna in revision surgery].

The exact and adequate management of diaphyesal fractures of the forearm is necessary to ensure forearm motion. Unsatisfactory treatment can lead to loss of function and disability of forearm and hand movement, resulting in severe patient morbidity. Since the rotational and angulatory stresses at the fracture site are the superior factors which influence the outcome of the forearm fracture healing after surgical treatment, the implants must fulfill some general prerequisites including high biomechanical stability, less invasive surgical approach and adequate biological features. However, less clinical studies are known for cases of complicated ulnar fractures when additional revision surgery is necessary to restore form and function. Thus, the choice of implant in such difficult situations requires a profound knowledge and experience. In a series of seven clinical cases we report about the successful use of the ForeSight-nail in revision surgery of complicated ulnar fractures. The series include cases with refractures after plate removal, in-situ plate brokerage and a critical size bone non-union which were treated with interlocking intramedullary osteosynthesis technique.

Adult↗

PubMed2004

[Monteggia injuries in adults: Critical analysis of injury pattern, management, and results].

BACKGROUND: Complications, revision surgery, and unsatisfactory functional results after operative management of Monteggia fractures are frequent. Moreover, hardly any studies exist that deal exclusively with the therapeutic concept for adults. PATIENTS AND METHODS: Between January 1988 and December 2001, 68 patients with Monteggia fractures or equivalent injury were surgically treated. A total of 49 patients could be followed up after 83 months (25-176). Fracture type was assessed according to Bado's classification, functional results according to the Mayo elbow performance score, and the extent of osteoarthritis based on the criteria of Baird and Johnson. RESULTS: The median age of the follow-up patients was 38 years (18-89, 31 men, 18 women). Corresponding to Bado's classification the following injuries were observed: 18 cases of type 1, 22 of type 2, 5 of type 3, and 4 cases of type 4. After surgical intervention, 14 patients achieved "very good", 21 "good", 9 "satisfactory", and 5 "poor" results. Of the 14 patients with either "satisfactory" or "poor" results, 9 manifested a type 2 injury. Complications requiring revision surgery occurred in 14 patients and complications not requiring revision in another 14. Severe osteoarthritic changes in the humeral or radioulnar joint were observed in 4 cases. CONCLUSIONS: Monteggia fractures in adults are fraught with complications despite good functional results in the majority of cases. The patient should be made aware early on of the risk of residual functional deficits and the need for further surgical intervention.

Adolescent↗

PubMed2004

Olecranon fractures in adults: factors influencing outcome.

In a retrospective, non-randomized study, we reviewed our experience with the operative treatment of olecranon fractures to find out which factors correlate with subjective complaints and functional outcome. A total of 95 consecutive olecranon fractures were operatively treated in our level I trauma institution between 1 March 1992 and 1 March 2000. Medical records and X-rays of all patients were evaluated. Three patients died, 23 were lost to follow-up. Fifty-eight of 69 available patients (84.0%) were reviewed clinically and/or radiologically after a mean time of 36 months. Fracture type, fracture classification, associated lesions, technical correctness of osteosynthesis, age and comorbidity were analysed. Radiological end result (intraarticular steps, gaps, arthrosis), subjective complaints, mobility of the elbow joint and muscle strength were evaluated. Patients with an unstable elbow (Mayo classification Type III and Schatzker-Schmeling classification Type D) had a higher loss of elbow function than others. There was a correlation between fracture morphology (fractures Type C and Type D in the Schatzker-Schmeling classification) and arthrosis. There also was a correlation between suboptimal osteosynthesis and arthrosis. There was no correlation between suboptimal osteosynthesis, implant loosening and secondary procedures. Patients more often expressed subjective complaints and loss of function in activities of daily life before than after metal removal. Primary elbow instability and fracture morphology are prognostic factors for elbow function and development of arthrosis after operative treatment of olecranon fractures. We, therefore, recommend the classification systems of the Mayo-clinic or of Schatzker-Schmeling. As many patients have complaints related to the implants, we recommend metal removal after fracture healing.

Adult↗

PubMed2004

Functional results after operative treatment of olecranon fractures.

In a retrospective, nonrandomized study, we reviewed our experience with the operative treatment of olecranon fractures to find out which factors correlate with subjective complaints and functional outcome. A total of 95 consecutive olecranon fractures were operatively treated in our level I trauma institution between March 1, 1992 and March 1, 2000. Medical charts and radiographs of all patients were evaluated. Three patients died, 23 were lost to follow-up. Fifty-eight of 69 available patients (84.0%) were reviewed clinically and/or radiologically after a mean time interval of 36 months. Fracture type, fracture classification, associated lesions, technical correctness of osteosynthesis, age and comorbidity were analysed. Radiological end result (intraarticular step-offs, gaps, arthrosis), subjective complaints, mobility of the elbow joint and muscle strength were evaluated. Patients with an unstable elbow (Mayo classification type III and Schatzker-Schmeling classification type D) had a higher loss of elbow function than others. There was a correlation between fracture morphology (fractures type C and D in the Schatzker-Schmeling classification) and arthrosis. There also was a correlation between suboptimal osteosynthesis and arthrosis. There was no correlation between suboptimal osteosynthesis, implant loosening and secondary procedures. Patients more often expressed subjective complaints and loss of function in activities of daily life before than after hardware removal. Primary elbow instability and fracture morphology are prognostic factors for elbow function and development of arthrosis after operative treatment of olecranon fractures. We therefore recommend the classification systems of the Mayo-clinic or of Schatzker-Schmeling. As many patients have complaints related to the implants, we recommend hardware removal after fracture healing.

Adult↗

PubMed2004

[Are angle-fixed implants with elastic properties advantageous for the internal fixation of proximal humerus fractures?].

There is a recent interest for the use of angle-fixed plates in the management of proximal humerus fractures. Rigid implants might be associated with an increased risk of cutting-out. In order to analyse the potential beneficial effects of the implant elasticity on fracture fixation, the biomechanical properties of a rigid and an elastic angle-fixed plating system were assessed in an experimental study. An unstable fracture of the surgical neck was created in 8 pairs of human humeri. Specimens were subjected to axial loading and torque. Stiffness, subsidence and load to failure were assessed. The implant with elastic properties was characterized by a lower torsional stiffness and a higher subsidence during axial loading and torque. This implant failed at lower loads than the rigid implant did. Elastic implant properties of angle-fixed plates have shown not to be advantageous for the management of fractures of the proximal humerus.

Bone Plates↗

PubMed2003

[Mortality, morbidity and functional outcome after open book and lateral compression lesions of the pelvic ring. A retrospective analysis of 100 type B pelvic ring lesions according to Tile's classification].

A retrospective study was made of 100 Tile type B and 122 type C pelvic ring lesions. Type B1-open book lesions occurred in 52 patients while 48 had lateral compression lesions of type B2 or B3. Only 13.1% of the patients showed no associated lesions. The frequency of associated neurological lesions in the B1 group with 21% was higher than in the B2/B3 group with 12%. The frequency of urologic lesions in group B1 was 9.6% but in B2/B3 patients it was only 2.1%. A total of 66% of B-lesion patients were stabilized with an external fixator. The frequency of secondary operative procedures was 23% in B1-patients and 6.25% in the B2/B3 group. Overall mortality was 10.4%: 5% in the B-group and 14.8% in the C-group. Outcome for patients with B2/B3 lesions was, with 92% excellent and good end results,much better than in patients with B1 lesions (74%). The inverse was true for radiologic results: 93% of the B1- but only 75% of the B2/B3-patients had an anatomical reduction. Open book lesions, lateral compression lesions and combined vertical stable lesions should be differentiated. We suggest that lateral compression lesions be characterized as B1 and open book lesions as B2 type injuries in the classification system of AO.

Adolescent↗

PubMed2003

[Prevention of thromboembolism in trauma surgery by dose adjustment of low molecular weight heparin depending on levels of TAT and D-dimer].

Deep vein thrombosis (DVT) is reported in up to 40% of trauma patients. The individual risk is nearly unpredictable. A daily single dose of a low molecular weight heparin (LMWH) was administered as prophylaxis to 518 trauma patients who were examined preoperatively and up to 10 days postoperatively in a prospective study. They were divided into two groups: group I comprised surgery of the hip and femur as well as total knee replacement and group II knee and lower leg surgery. Thrombin-antithrombin complex and D-dimer were analyzed. A second daily dose of LMWH was added if D-dimer exceeded the cutoff. If ultrasound was suspicious for DVT venography was added. Deep vein thrombosis was seen in five cases (group I=4, group II=1), without pulmonary embolism. TAT and D-dimer were significantly higher in group I than in group II ( p<0.005). One hundred patients, 79 of them belonging to group I, were treated with a second dose of LMWH. The daily cutoff had the highest sensitivity and specificity for day 4. Due to individual monitoring of coagulation markers, the risk for thromboembolism compared to actual data in the literature seems to be reduced.

Anticoagulants↗