David Pokorny

A new technique for reconstruction of the proximal humerus after three- and four-part fractures

The results of proximal humeral replacement following trauma are substantially worse than for osteoarthritis or rheumatoid arthritis. The stable reattachment of the lesser and greater tuberosity fragments to the rotator cuff and the restoration of shoulder biomechanics are difficult. In 1992 we developed a prosthesis designed to improve fixation of the tuberosity fragments in comminuted fractures of the proximal humerus. The implant enables fixation of the fragments to the shaft of the prosthesis and the diaphyseal fragment using screws, washers and a special toothed plate. Between 1992 and 2003 we used this technique in 50 of 76 patients referred to our institution for shoulder reconstruction after trauma. In the remaining 26, reconstruction with a prosthesis and nonabsorbable sutures was performed, as the tuberosity fragments were too small and too severely damaged to allow the use of screws and the toothed plate. The Constant score two years post-operatively was a mean of 12 points better in the acute trauma group and 11 points better in the late post-traumatic group than in the classical suture group. We recommend this technique in patients where the tuberosity fragments are large enough to allow fixation with screws, washers and a toothed plate.

Sciatic nerve palsy after total hip replacement

We report a case of sciatic nerve palsy following total hip replacement which has lead to a novel hypothesis to account for this complication.

Distribution of polyethylene wear particles and bone fragments in periprosthetic tissue around total hip joint replacements.

Ultra-high molecular weight polyethylene (UHMWPE) wear particles play a significant role in failures of total joint replacements (TJRs). In this work, we investigated the distribution of these wear particles in periprosthetic tissues obtained from nine revisions of hip TJR. In the first step, all periprosthetic tissues were combined and mechanically separated into granuloma tissue (containing hard granules visible to the naked eye) and surrounding tissue (without visible granules). In the second step, the tissues were hydrolyzed by protease from Streptomyces griseus and granules were separated by filtration; this divided the sample into four groups: (i) lyzate and (ii) non-degraded large granules from the granuloma tissue plus (iii) lyzate and (iv) non-degraded small granules from the surrounding tissue. In the third step, the large as well as small granules were hydrolyzed by collagenase from Clostridium histolyticum. In the last step, the UHMWPE wear particles from all four groups were purified by HNO3 digestion and weighed. The purity of the isolated particles was verified by scanning electron microscopy, infrared spectroscopy and energy-dispersive X-ray analysis. Of the total amount of polyethylene particles in the whole granuloma tissue, 72% of particles in the size range 0.1-10 microm and 68% of those larger than 10 microm were found in granules. Therefore, the formation of granules significantly lowers the effective amount of wear particles available for interaction with reactive cells and seems to be a natural defense mechanism.

The Long Oblique Revision component in revision arthroplasty of the hip

Migration of the acetabular component may give rise to oval-shaped bone defects in the acetabulum. The oblong implant is designed to fill these defects and achieve a stable cementless anchorage with no significant bone loss. We prospectively reviewed 133 oblong long oblique revision components at a mean follow-up of 9.74 years (0.6 to 14). All had been used in revisions for defects of type IIB to IIIB according to Paprosky. Aseptic loosening was the reason for revision in 11 cases (8.3%) and deep infection in seven (5.3%). The probability of implant survival over a 12-year follow-up estimated by the Kaplan-Meier method gave a survival rate of 0.85% respectively 0.90% when deep infection was excluded as the endpoint. Our study supports the use of these components in defects from IIB to IIIA. The main precondition for success is direct contact of more than half of the surface of the implant with the host acetabular bone.

Zweizeitige Operation zur Behandlung tiefer Infektionen bei Hüftendoprothesen unter Verwendung eines kanülierten Platzhalters

ZusammenfassungOperationsziel Einsetzen eines soliden antibiotikahaltigen PMMA-Platzhalters in der ersten Operation eines zweizeitigen Hüftrevisionseingriffs wegen tiefer Infektion bei Hüftendoprothese.Dadurch Vermeidung einer Beinverkürzung und Erreichen einer toxischen lokalen Antibiotikakonzentration. Indikationen Tiefe Infektion nach Hüfttotalendoprothesen, insbesondere wenn die Femurkomponente betroffen ist. Kontraindikationen Große Knochendefekte am proximalen Femur.Schlechter Allgemeinzustand, der keine Revisionsoperation mehr zulässt. Operationstechnik Entfernung beider Komponenten, ausgiebiges Débridement mit Entfernung des alten Zements. Intraoperative Formung eines kanülierten Spacers mit antibiotikahaltigem Knochenzement im Stil einer Moore-Prothese. Kanülierung mit einem Charrière-16-Redon-Drain, in den ein passender Kirschner-Draht eingeführt wird. Nach Aushärten des Zements Entfernung des Kirschner-Drahts und Kürzen des Drains. Ein Charrière-8-Drain wird in den Spacer geschoben, und die Hüfte wird reponiert. Ergebnisse Der Spacer wurde in 29 Fällen mit tiefem Hüftendoprotheseninfekt angewendet. Das Intervall zwischen Implantation des Spacers und Wiedereinbau einer Hüftendoprothese betrug 11,6 Wochen. Nach Spacerimplantation traten in zwei Fällen Reinfektionen auf, die ein zweites Débridement mit Implantation eines neuen Spacers und eine Spülung erforderten. Unsere Erfolgsrate mit dieser zweizeitigen Revisionsoperation beträgt 96,5%. Die Patienten erreichten im Harris-Hip-Score durchschnittlich 90,1 Punkte. Brüche des Spacers traten zweimal, Luxationen fünfmal auf; beide hatten keinen Einfluss auf das Endergebnis.AbstractObjective Eradication of infection through insertion of a solid antibiotic-loaded PMMA spacer during the first stage of a twostage reimplantation for deep infection to prevent shortening, to obtain a high local concentration of antibiotics in and to permit lavage of the medullary canal. Indications Deep infection after total hip arthroplasty (THA) in patients who are candidates for revision surgery, especially in instances where the infection is confined to the region of femoral component. Contraindications Large defect of proximal femur.Poor general health not allowing two procedures. Surgical Technique Extraction of both components, removal of all necrotic material and cement. Intraoperative manual modeling of a cannulated spacer using bone cement premixed with antibiotics, its shape resembling a Moores prosthesis. The spacer is shaped around a size 16 drain into which a corresponding Kirschner wire is inserted. Once the spacer is completely set, the Kirschner wire is removed and the drain shortened. A size 8 lavage drain tube is then inserted into the spacer and the hip reduced. Results We used the spacer in the treatment of 29 patients with infected THA. The interval between spacer implantation and insertion of the total hip implants was 11.6 weeks. Reinfection after implantation of the spacer was observed twice necessitating a second debridement, implantation of a new spacer, and lavage. Success rate of two-stage revision was 96.5%. The Harris hip score reached an average of 90.1 points. Breakage of the spacer was observed twice, and dislocation occurred in five patients; both did not affect the final result.

Quantification of structural changes of UHMWPE components in total joint replacements

BackgroundAt present time the number of implantations of joint replacements as well as their revisions increases. Higher demands are required on the quality and longevity of implants. The aim of this work was to determine the degree of oxidative degradation and the amount of free/residual radicals in selected ultra-high molecular weight polyethylene (UHMWPE) components of the joint replacements and demonstrate that the measured values are closely connected with quality and lifetime of the polymer components.MethodsWe tested both new (4 samples) and explanted (4 samples) UHMWPE polymers for total joint replacements. The samples were characterized by infrared spectroscopy (IR), electron spin resonance (ESR) and microhardness (MH) test. The IR measurements yielded the values of oxidation index and trans-vinylene index. The ESR measurements gave the free radicals concentration.ResultsIn the group of new polyethylene components, we found oxidation index values ranging from 0.00-0.03 to 0.24. The trans-vinylene index values ranged from 0.044 to 0.080. The value of free radical concentration was zero in virgin and also in sample of Beznoska Company and non-zero in the other samples. In the group of explanted components, the measured values were associated with their history, micromechanical properties and performance in vivo.ConclusionsWe demonstrated that measuring of oxidative damage may help the orthopaedic surgeon in estimating the quality of UHMWPE replacement component and thus radically to avoid early joint replacement failure due to worse polyethylene quality.

Study of the variability of scapular inclination and the glenoid version - considerations for preoperative planning: clinical-radiological study

BackgroundPreoperative planning with the aid of imaging methods is a principal factor in successful surgery on the shoulder. This work aims to evaluate the variability of glenoid version, spiralling twist and scapular inclination in relation to the frontal axis. Studies focusing on measuring the variability of scapular inclination in the standardised rest position are lacking in the literature.MethodsWe evaluated 104 CT scans of the shoulder. We measured the glenoid version with respect to the scapular axis at three levels. We measured the scapular inclination angle in relation to the sagittal plane and we determined scapular inclination in relation to the frontal axis. Statistical evaluation was performed using the marginal linear model and parameters were estimated using the generalised least squares method, which enables the dependency of measurements performed on the same subject to be taken into consideration.ResultsThe highest values of retroversion are attained by the glenoid in the cranial section (average -9.96°, range -29.7 to +13.2°). Proof of the spiralling twist is the decline in retroversion at the centre of the glenoid (average -2.09°, range -16.7 to +11.6°).Retroversion decreases further in the inferior direction (average -0.5°, range -20.9 to +17.5°). The average thoracoscapular angle is 45.46°, ranging from 13.1 to 69.0°. The average scapular inclination in relation to the frontal plane is 44.54°, ranging from 21.0 to76.9°.ConclusionsDuring preoperative planning, the surgeon should take into consideration not only the glenoid version in relation to the scapular axis, but also the value of the scapular inclination so as to eliminate possible surgical errors, optimise prosthesis implantation and thus decrease the risk of functional restrictions of the joint.Clinical trial registrationEthics Committee for Multi-Centric Clinical Trials (EK-554/14,29thApril 2014).

Results of clinical application of a new-generation total knee joint endoprosthesis with a rotating insert, manufactured by «BEZNOSKA s.r.o.» Company

The article contains results of surgical treatment of 76 knee joints with help of SVL/RP endoprostheses manufactured by «BEZNOSKA s.r.o.» Company. In compliance with a Visual Analogue Scale, a pain syndrome decrease was revealed from 6.7 points before the operation to 1.5 points after the prosthesic replacement. An integrated assessment by KSS scale demonstrated improvement in the operated joint functioning. Implants of «BEZNOSKA s.r.o.» Company are objects of choice for surgeons during total knee arthroplasty.