Influence of cementless hip stems on femoral cortical strain pattern depending on their extent of porous coating

The extent of porous coating of cementless total hip stems is held responsible for radiological periprosthetic changes, the rate of thigh pain, and even its long-term success. However, there is only sparse knowledge on how the biomechanical loading conditions of the femur are influenced by the extent of porous coating in the early phase after implantation of a cementless hip stem. Aiming to evaluate the effect of surface structuring on the strain pattern of the femur, we implanted three anatomic hip stems with different extents of porous coating (full, two-thirds proximal, and penguin type) in second-generation composite femora coated with a photoelastic layer. A cortical strain mapping was conducted before and after insertion of the implants under standardized loading conditions considering relevant muscle forces. The results of the statistical analysis of three different implantation sequences proved that composite femora are suitable for repeated measurements within the applied experimental setup. Cortical strain changes including stress-shielding effects medially (-60%) and laterally (-50%) were validated with a cadaver femur. The extent of porous coating had no significant influence on the surface strain pattern for an immediate postoperative situation

Economic Impact of Infected Total Knee Arthroplasty

Background. An enormous economic impact can be observed for infected total knee arthroplasties (TKA). The aim of the present study was to evaluate whether a cost covering treatment of infected TKA is feasible in the German DRG System. Patients and Methods. Average total treatment costs were evaluated for infected TKA and compared with a matched pair of primary TKA. Data was generated using the health record and the hospitals' health information system. Results were evaluated and compared regarding the total personnel and material costs with respect to the financial receipts. Results. A total of 28 patients diagnosed with an infected TKA were included. A significant increase in the average length of stay, use of medical supplies and third party medical examinations were found for the infected TKA. An average deficiency of 6,356€ per patient was observed for the infected TKA. An average profit of 927€ per patient was made performing primary TKA. Conclusions. A cost-effective treatment of infected TKA was not feasible with the receipts from the German DRG System. An adaption of the receipts has to be evaluated. Moreover, other measures have to be considered in order to achieve a comprehensive medical yet financial reasonable standard in the treatment of infected TKA and THA

Two-stage revision of implant-associated infections after total hip and knee arthroplasty

Septic loosening of total hip and knee endoprostheses gains an increasing proportion of revision arthroplasties. Operative revisions of infected endoprostheses are mentally and physically wearing for the patient, challenging for the surgeon and a significant economic burden for healthcare systems. In cases of early infection within the first three weeks after implantation a one-stage revision with leaving the implant in place is widely accepted. The recommendations for the management of late infections vary by far. One-stage revisions as well as two-stage or multiple revision schedules have been reported to be successful in over 90% of all cases for certain patient collectives. But implant associated infection still remains a severe complication. Moreover, the management of late endoprosthetic infection requires specific logistics, sufficient and standardized treatment protocol, qualified manpower as well as an efficient quality management. With regard to the literature and experience of specialized orthopaedic surgeons from several university and regional hospitals we modified a commonly used treatment protocol for two-stage revision of infected total hip and knee endoprostheses. In addition to the achievement of maximum survival rate of the revision implants an optimisation of the functional outcome of the affected artificial joint is aimed for

The effect of continuous passive motion and sling exercise training on clinical and functional outcomes following total knee arthroplasty: a randomized active-controlled clinical study

BACKGROUND: The parallel-group randomized active-controlled clinical study was conducted to compare the effectiveness of two in-hospital range of motion (ROM) exercise programs following total knee arthroplasty (TKA). Continuous passive motion (CPM) is frequently used to increase ROM and improve postoperative recovery despite little conclusive scientific evidence. In contrast, a new active sling-based ROM therapy requires the activation of the knee joint muscles and dynamic joint stabilization. It was hypothesized that higher demands on muscle strength and muscle coordination during sling exercise training (ST) might be advantageous for early recovery following TKA. METHODS: A total of 125 patients undergoing primary TKA were assessed for eligibility. Thirty-eight patients were randomly assigned to receive ST or CPM (control intervention) during hospital stay. Patients were assessed before TKA for baseline measurement (pretest), 1 day before discharge (posttest) and 3 months after TKA (follow-up). The passive knee flexion range of motion (pFL) was the primary outcome measure. Secondary outcome measures included active knee flexion range of motion, active and passive knee extension ROM, static postural control, physical activity, pain, length of hospital stay as well as clinical, functional and quality-of-life outcomes (SF-36, HSS and WOMAC scores). Data were analyzed according to the intention-to-treat principle. Differences between the groups were tested for significance by the unpaired Student’s t test or an analysis of covariance (ANCOVA) adjusted for baseline, weight, sex, age, pain and physical activity. RESULTS: A between-group difference could be determined at posttest. The pFL was significantly higher by 6.0° (95% CI 0.9 to 11.2°; P = 0.022) in the ST group. No difference between groups in pFL was documented at follow-up. Furthermore, no significant differences could be observed for any secondary outcome measure at posttest and follow-up. CONCLUSIONS: ST seems to have a clinically relevant beneficial short-term effect on pFL compared to CPM. The results support the implementation of ST in rehabilitation programs following TKA. LEVEL OF EVIDENCE: Therapy, level 2

The Influence in Airforce Soldiers Through Wearing Certain Types of Army-Issue Footwear on Muscle Activity in the Lower Extremities

The objective of the study was to analyse the influence of the shape and material of the military footwear worn by soldiers on muscle activity in the lower extremities, and whether such footwear could explain specific strain complaints and traumatic lesions in the region of the lower extremities

Analysis of the Release Characteristics of Cu-Treated Antimicrobial Implant Surfaces Using Atomic Absorption Spectrometry

New developments of antimicrobial implant surfaces doped with copper (Cu) ions may minimize the risk of implant-associated infections. However, experimental evaluation of the Cu release is influenced by various test parameters. The aim of our study was to evaluate the Cu release characteristics in vitro according to the storage fluid and surface roughness. Plasma immersion ion implantation of Cu (Cu-PIII) and pulsed magnetron sputtering process of a titanium copper film (Ti-Cu) were applied to titanium alloy (Ti6Al4V) samples with different surface finishing of the implant material (polished, hydroxyapatite and corundum blasted). The samples were submersed into either double-distilled water, human serum, or cell culture medium. Subsequently, the Cu concentration in the supernatant was measured using atomic absorption spectrometry. The test fluid as well as the surface roughness can alter the Cu release significantly, whereby the highest Cu release was determined for samples with corundum-blasted surfaces stored in cell medium

Effects of Wearing Different Personal Equipment on Force Distribution at the Plantar Surface of the Foot

Background. The wearing of personal equipment can cause specific changes in muscle activity and posture. In the present study, we investigated the influence of differences in equipment related weight loading and load distribution on plantar pressure. In addition, we studied functional effects of wearing different equipment with a particular focus on relevant changes in foot shape. Methods. Static and dynamic pedobarography were performed on 31 male soldiers carrying increasing weights consisting of different items of equipment. Results. The pressure acting on the plantar surface of the foot increased with higher loading, both under static and dynamic conditions (p < 0.05). We observed an increase in the contact area (p < 0.05) and an influence of load distribution through different ways to carry the rifle. Conclusions. The wearing of heavier weights leads to an increase in plantar pressure and contact area. This may be caused by flattening of the transverse and longitudinal arches. The effects are more evident in subjects with flat feet deformities which seem to flatten at an earlier load condition with a greater amount compared to subjects with normal arches. Improving load distribution should be a main goal in the development of military equipment in order to prevent injuries or functional disorders of the lower extremity

Low-Load Unilateral and Bilateral Resistance Training to Restore Lower Limb Function in the Early Rehabilitation After Total Knee Arthroplasty: A Randomized Active-Controlled Clinical Trial

Background: Continuous passive motion (CPM) is frequently used during rehabilitation following total knee arthroplasty (TKA). Low-load resistance training (LLRT) using continuous active motion (CAM) devices is a promising alternative. We investigated the effectiveness of CPM compared to LLRT using the affected leg (CAMuni) and both legs (CAMbi) in the early post-operative rehabilitation. Hypotheses: (I) LLRT (CAMuni and CAMbi) is superior to CPM, (II) additional training of the unaffected leg (CAMbi) is more effective than unilateral training (CAMuni).Materials and Methods: Eighty-five TKA patients were randomly assigned to three groups, respectively: (i) unilateral CPM of the operated leg; (ii) unilateral CAM of the operated leg (CAMuni); (iii) bilateral alternating CAM (CAMbi). Patients were assessed 1 day before TKA (pre-test), 1 day before discharge (post-test), and 3 months post-operatively (follow-up). Primary outcome: active knee flexion range of motion (ROMFlex). Secondary outcomes: active knee extension ROM (ROMExt), swelling, pain, C-reactive protein, quality of life (Qol), physical activity, timed-up-and-go performance, stair-climbing performance, quadriceps muscle strength. Analyses of covariances were performed (modified intention-to-treat and per-protocol).Results: Hypothesis I: Primary outcome: CAMbi resulted in a higher ROMFlex of 9.0° (95%CI −18.03–0.04°, d = 0.76) and 6.3° (95%CI −14.31–0.99°, d = 0.61) compared to CPM at post-test and follow-up, respectively. Secondary outcomes: At post-test, C-reactive protein was lower in both CAM groups compared with CPM. Knee pain was lower in CAMuni compared to CPM. Improved ROMExt, reduced swelling, better stair-climbing and timed-up-and-go performance were observed for CAMbi compared to CPM. At follow-up, both CAM groups reported higher Qol and CAMbi showed a better timed-up-and-go performance. Hypothesis II: Primary outcome: CAMbi resulted in a higher knee ROMFlex of 6.5° (95%CI −2.16–15.21°, d = 0.56) compared to CAMuni at post-test. Secondary outcomes: At post-test, improved ROMExt, reduced swelling, and better timed-up-and-go performance were observed in CAMbi compared to CAMuni.Conclusions: Additional LLRT of the unaffected leg (CAMbi) seems to be more effective for recovery of function than training of the affected leg only (CAMuni), which may be mediated by positive transfer effects from the unaffected to the affected limb (cross education) and/or preserved neuromuscular function of the trained, unaffected leg.Trial Registration:ClinicalTrials.gov Identifier: NCT02062138