Ulf J. Schlegel

Injuries and Overuse Syndromes in Powerlifting

Powerlifting is a discipline of competitive weightlifting. To date, no investigations have focused on pain encountered during routine training. The aim of the study was to identify such pain, assign it to particular exercises and assess the data regarding injuries as well as the influence of intrinsic and extrinsic factors. Data of 245 competitive and elite powerlifters was collected by questionnaire. Information regarding current workout routines and retrospective injury data was collected. Study subjects were selected from 97 incorporated powerlifting clubs. A percentage of 43.3% of powerlifters complained of problems during routine workouts. Injury rate was calculated as 0.3 injuries per lifter per year (1 000 h of training=1 injury). There was no evidence that intrinsic or extrinsic factors affected this rate. Most commonly injured body regions were the shoulder, lower back and the knee. The use of weight belts increased the injury rate of the lumbar spine. Rate of injury to the upper extremities was significantly increased based on age >40 years (shoulder/p=0.003, elbow/p=0.003, hand+wrist/p=0.024) and female gender (hand+wrist/p=0.045). The daily workout of a large proportion of powerlifters is affected by disorders which do not require an interruption of training. The injury rate is low compared to other sports.

Pulsed lavage improves fixation strength of cemented tibial components

Pulsatile lavage is purported to improve radiographic survival in cemented total knee arthroplasty (TKA). Similarly, a potential improvement of fixation strength of the tibial tray has been assumed based on the increased cement penetration. In this study, the influence of pulsed lavage on fixation strength of the tibial component and bone cement penetration was evaluated in six pairs of cadaveric specimens. Following surgical preparation, the tibial surface was irrigated using pulsatile lavage on one side of a pair, while on the other side syringe lavage was applied. All tibial components were implanted using the same cementing technique. Cement penetration and bone mineral density was assessed based on computed tomography data. Fixation strength of the tibial trays was determined by a pull-out test with a material testing machine. Median pull-out forces and cement penetration were significantly (p = 0.031) improved in the pulsed lavage group as compared to the syringe lavage group. Enhanced fixation strength is suggested as being a key to improved survival of the implant. Consequently, pulsatile lavage should be considered as a mandatory preparation step when cementing tibial components in TKA.

Efficacy of vacuum bone cement mixing systems in reducing methylmethacrylate fume exposure: comparison of 7 different mixing devices and handmixing.

Background Polymethylmethacrylate (PMMA) bone cements are mainly used for implant fixation in joint replacement surgery. During cement preparation for application, all staff in the operating theatre are exposed to methylmethacrylate (MMA) fumes, which are known to have toxic side effects.Methods and results In this study we found that vacuum mixing of bone cement with 7 commercially available mixing devices significantly reduced the emission of MMA vapors in the breathing zone when compared with classic hand mixing in an open bowl. Gas chromatography appears to be more sensitive for detection of MMA fumes than Photo Inonization Detection.Interpretation According to present knowledge, even repeated mixing of PMMA bone cement during a normal working day does not seem to constitute an increased health risk, particularly if vacuum mixing is implemented.

Clinical Outcomes and Quality of Life 1 Year after Open Microsurgical Decompression or Implantation of an Interspinous Stand-Alone Spacer

BACKGROUND Interspinous stand-alone implants are inserted without open decompression to treat symptomatic lumbar spinal stenosis (LSS). The insertion procedure is technically simple, low-risk, and quick. However, the question remains whether the resulting clinical outcomes compare with those of microsurgical decompression, the gold standard. MATERIAL AND METHODS This prospective, comparative study included all patients (n=36) with neurogenic intermittent claudication (NIC) secondary to LSS with symptoms improving in forward flexion treated operatively with either interspinous stand-alone spacer insertion (Aperius (®); Medtronic, Tolochenaz, Switzerland) (group 1) or microsurgical bilateral operative decompression (group 2) between February 2007 and November 2008. Data (patient data, operative data, COMI, SF-36 PCS and MCS, ODI, and walking tolerance) were collected preoperatively as well as at 6 weeks, at 3, 6, and 9 months, and at one year follow-up (FU). All patients had complete FU over 1 year. RESULTS Compared to preoperative measurements, surgery led to improvements of all parameters in the entire collective as well as both individual groups. There were no statistically relevant differences between the 2 groups over the entire course of FU. However, improvements in the ODI and SF-36 MCS were not significant in group 1, in contrast to those of group 2. Also, although in group 1 the improvements in leg pain (VAS leg) were still significant (p<0.05) at 6 months, this was no longer the case at 1 year FU. In group 1 at 1 year FU an increase in leg pain was observed, while in group 2,  minimal improvements continued. Walking tolerance was significantly improved at all FU times compared to preoperatively, regardless of group (p<0.01). At no time there was a significant difference between the groups. In group 1, admission and operative times were shorter and blood loss decreased. The complication rate was 0% in group 1 and 20% in group 2, however reoperation was required by 27.3% of group 1 patients and 0% of group 2. CONCLUSION Implantation of an interspinous stand-alone spacer yields clinical success comparable to open decompression, at least within the first year of FU. The 1-year conversion rate of 27.3% is, however, decidedly too high.

[Acetabular reinforcement rings in revision total hip arthroplasty: midterm results in 298 cases].

BACKGROUND Acetabular revision in total hip arthroplasty (THA), especially for loose or migrated cup components with collateral bone loss, remains a great surgical challenge. The aim should always be a functionally favorable reconstruction of the rotation center with sufficient load capacity of the acetabulum. Commonly used implants in Europe are the Mueller ring, the Ganz ring, and the Burch-Schneider cage. PATIENTS AND METHODS We report our results of 298 patients (298 hips) with a median follow-up period of 4 (range 0-17) years in a retrospective series. RESULTS Follow-up data were available in 224 cases (75%). A radiographic examination was performed in 176 (59%) patients. Another 54 patients (18%) had died in the follow-up period, while another three patients (1%) were lost to follow-up. Eighteen patients (16%) underwent re-revision, in nine cases for aseptic loosening and in the remaining nine cases for infection. In seven additional cases (2%), radiological and clinical failure was found during follow-up. The overall survival rate was 94% at 5 years and 89% at 8 years. CONCLUSION Revision THA using acetabular reinforcement rings results in acceptable midterm results. However, septic complications and lysis of the bone graft with consecutive failure of the reinforcement ring remain problematic.

Abstützschalen in der Revisionsendoprothetik der Hüfte

BACKGROUND Acetabular revision in total hip arthroplasty (THA), especially for loose or migrated cup components with collateral bone loss, remains a great surgical challenge. The aim should always be a functionally favorable reconstruction of the rotation center with sufficient load capacity of the acetabulum. Commonly used implants in Europe are the Mueller ring, the Ganz ring, and the Burch-Schneider cage. PATIENTS AND METHODS We report our results of 298 patients (298 hips) with a median follow-up period of 4 (range 0-17) years in a retrospective series. RESULTS Follow-up data were available in 224 cases (75%). A radiographic examination was performed in 176 (59%) patients. Another 54 patients (18%) had died in the follow-up period, while another three patients (1%) were lost to follow-up. Eighteen patients (16%) underwent re-revision, in nine cases for aseptic loosening and in the remaining nine cases for infection. In seven additional cases (2%), radiological and clinical failure was found during follow-up. The overall survival rate was 94% at 5 years and 89% at 8 years. CONCLUSION Revision THA using acetabular reinforcement rings results in acceptable midterm results. However, septic complications and lysis of the bone graft with consecutive failure of the reinforcement ring remain problematic.

Comparison of different cement application techniques for tibial component fixation in TKA

PurposeAseptic loosening of the tibial component remains a major cause for revision surgery in total knee arthroplasty (TKA). A stable initial fixation of the tibial implant has been suggested to reduce micromotion of the implant and could be decisive regarding its long-term performance. Different techniques for applying cement to the tibial surface have been described in the literature, with controversial results. No guidelines in favour of any particular approach are available.MethodsIn this study, we compared three commonly used cementing techniques (layered application, stem cementation, cement gun) with surface-only fingerpacking cementation following pulsed lavage (paired human tibiae, four groups, n = 24). Specimens underwent computed tomography scanning for three-dimensional analysis of cement penetration and mechanical testing for assessing interface strength.ResultsBone cement penetration decreased with increasing bone mineral density (BMD) (R2 = 0.18, p = 0.023), while interface strength increased with BMD (R2 = 0.56, p < 0.001). No significant effect of cementation techniques on cement penetration (p ≥ 0.069) or interface strength (p = 0.180) was found in any group.ConclusionAdequate surface preparation using pulsed lavage and copious drying of the tibial surface appears to be of overruling importance, thus limiting the effect of any particular technique applied to improve implant fixation. This study emphasises the fundamental importance of surface preparation and pulsed lavage in TKA.

An in vitro comparison of tibial tray cementation using gun pressurization or pulsed lavage.

PurposeAseptic loosening of the tibial component remains a limitation to the highly successful procedure of total knee arthroplasty (TKA). Pulsed lavage improves bone cement penetration and interface strength in tibial tray cementation. This study tested whether pressurized cement application with a cement gun can compensate the use of jet lavage for bone surface preparation.MethodsTibial components were implanted in six pairs of cadaveric tibiae. On one side, pulsed lavage of the tibial bone was combined with finger packing of bone cement; on the other side, syringe lavage and gun cementing was used. Cement penetration into the bone was determined from computed tomography scans, and Interface strength was determined by pull-out testing.ResultsCement penetration was greater (p = 0.004) and interface strength was higher (p = 0.028) in the pulsed lavage group.ConclusionPressurization of cement by gun application could not compensate for the omission of pulsed lavage. Thus, pulsed lavage should be considered a crucial factor in TKA to improve implant fixation, which cannot be compensated for by cement application technique.

Does Impaction Matter in Hip Resurfacing? A Cadaveric Study

Eight pairs of fresh frozen human femora were prepared for hip resurfacing. One side of each pair was impacted gently, the other side vigorously. After implantation procedure, specimens were loaded in a material testing machine to the ultimate fracture load. Median impaction loads on the vigorously implanted side were 11,298N compared to 1374N on the gently implanted side. Failure loads in the high-impact group (median, 8873N) were significantly (P = .0078) reduced when compared with the low-impact group (median, 9237N). The study stresses that meticulous reaming of the femoral head and the pinhole is of tremendous importance. Remaining obstacles can lead to excessive loads, while attempting to enforce the correct seating of the implant. Only careful, slight tapping should be applied to ensure final seating.

Ist die Navigation bei der Schlittenprothese sinnvoll

ZusammenfassungWir führten diese Pilotstudie am Leichenknie durch, um die Effektivität eines Navigationssystems bezüglich der Implantatpositionierung beim minimal-invasiven unikompartimentellen Kniegelenkersatz im Vergleich zum konventionellen Op.-Technik zu überprüfen. Wir untersuchten die Genauigkeit der Implantatpositionierung nach unikompartimentellem Kniegelenkersatz. Auf einer Seite wurde Standardinstrumentarium operiert auf der Gegenseite wurde ein Navigationssystem verwendet. Die radiologische Auswertung zeigte, dass mit beiden Methoden eine genaue Implantatposition erreicht wurde. Die Resektionshöhe im Bereich der proximalen Tibia war in der navigierten Gruppe etwas geringer als in der manuellen Gruppe. Die Positionierung der Femurkomponente war mittels Navigation genauso gut wie in der manuellen Gruppe mit intramedullärer Ausrichtung. Die Pilotstudie zeigte, dass die Computernavigation genauso exakte Implantationsergebnisse liefern kann wie die manuelle Op.-Technik. Insgesamt zeigt die Navigation die gleiche Genauigkeit wie das Standardinstrumentarium und kann zusätzlich die Orientierung des Operateurs bei minimal-invasivem Zugang verbessern.AbstractWe conducted this pilot cadaver study to investigate whether the use of a navigation system during minimally invasive unicompartmental knee arthroplasty leads to more consistent results than the conventional hand-guided technique. We describe the accuracy of implant positioning in using standard instrumentation and computer navigation. Radiographic assessment showed that accurate component placement was achieved using both methods. These results were not statistically significant. The computer navigated femoral component placement without intramedullary (IM) rod was as accurate as the conventional method with IM rod. The study showed that computer navigation can produce accurate results even without an intramedullary rod. Image guidance can maintain the accuracy of the standard instrumentation and enhance 3D vision and the intraoperative orientation of the surgeon.