Introduction

Recent studies suggested that the progression of osteoarthritis (OA), a chronic degenerative joint disease, may be affected by the autonomic nervous system (ANS). Under healthy conditions, the sympathetic (SNS) and parasympathetic (PNS) branches of the ANS are well coordinated to maintain homeostasis. However, pathological conditions are frequently associated with a disturbance of this fine-tuned balance. Therefore, we analyzed whether an autonomic dysfunction occurs in OA patients.

Osteoarthritis (OA) is the most common degenerative joint disorder. Its multifactorial etiology includes age, sex, joint overloading, genetic or nervous influences. In particular, the autonomic nervous system is increasingly gaining in importance. Its two branches, the sympathetic (SNS) and parasympathetic nervous system, are well-balanced under healthy conditions. OA patients seem to be prone to an autonomic imbalance and therefore, we analyzed their autonomic status.

More than 200 participants including patients with early and late stage knee OA (before and 1 year after knee replacement surgery) and healthy probands (age-matched) were analyzed. Heart rate variability was measured via electrocardiogram to assess long-term sympathetic (low-frequency=LF) and parasympathetic (high-frequency=HF, pRR50) activities or general variability (RMSSD, SDRR). Serum cortisol concentrations were measured by ELISA. Perceived chronic stress (PSQ) was assessed via questionnaire. Multivariant regression was performed for data analysis. LF/HF value of early OA was slightly increased compared to healthy controls but significantly higher compared to late OA patients before (p>0.05) and after TKR (p>0.01). HF in late OA patients before TKR was significantly decreased compared to patients after TKR (p>0.001) or healthy controls (p>0.05). Healthy probands exhibited the highest SDRR values, early OA patients had slightly lower levels and late OA patients before TKR displayed significantly reduced SDRR (p>0.001). The same differences were observed in pRR50 and RMSSD. Serum cortisol concentrations and PSQ scores increased in late OA patients before TKR. At the time point of TKR, women with beta blocker medication had significantly higher age (71 ± 9 years) than those without (63 ± 12 years)(p>0.01). An autonomic dysfunction with sympathetic dominance occurs in OA patients. The fact that beta blocker medication in women delayed the need of TKR indicates that SNS inhibition might counteract OA. Future therapeutic interventions for OA should consider a systemic approach with special regard on the ANS.

Aims

Accurate skeletal age and final adult height prediction methods in paediatric orthopaedics are crucial for determining optimal timing of growth-guiding interventions and minimizing complications in treatments of various conditions. This study aimed to evaluate the accuracy of final adult height predictions using the central peak height (CPH) method with long leg X-rays and four different multiplier tables.

Introduction

Wear plays a key role in the clinical outcome of total hip replacements (THR). In addition, increased frictional moment can stress the implant interfaces which may lead to high torsional loadings in the intermodular taper junction (fretting) and cup loosening and to the development of noise (squeaking). Against the background of larger head diameters (increased range of motion and decreased risk of dislocation), the friction induced by the joint articulation is of particular interest. As of now, the investigation of friction with the use of relevant joint kinematics and loadings are limited to numerical studies. Experimental approaches use simplified models which do not take into consideration complex activities. Thus, with the aim of this study is the identification of articular frictional moments that consider critical in vivo loading conditions and kinematics as well as the clinical cup inclination, head size and clearance of ceramic-on-ceramic hip bearings.

The numbers of anatomic total shoulder joint replacements (ATSR) is increasing during the past years with encouraging clinical results. However, the survivorship of ATSR is lower as compared to total knee and hip replacements. Although the reasons for revision surgery are multifactorial, wear-associated problems like loosening are well-known causes for long-term failure of ATSR. Furthermore there is lack of valid experimental wear tests for ATSR. Therefore the purpose of this study was to define experimental wear testing parameters for ATSR and to perform a wear study comparing ceramic and metallic humeral heads.

Kinetic and kinematic data were adopted from in-vivo loading measurements of the shoulder joint (orthoload.com) and from several clinical studies on shoulder joint kinematics. As activity an ab/adduction motion of 0 to 90° in combination with an ante/retroversion while lifting a load of 2 kg has been chosen. Also a superior-inferior translation of the humeral head has been considered. The wear assessment was performed using a force controlled AMTI joint simulator for 3×10⁶ cycles (Fig. 1) and polyethylene wear has been assed gravimetrically.

The studied ATSR (Turon^TM, DJO Surgical, USA) resulted in a polyethylene wear rate of 62.75 ± 1.60 mg/10⁶ cycles in combination with metallic heads. The ceramic heads significantly reduced the wear rate by 26.7 % to 45.99 ± 1.31 mg/10⁶ (p<0.01). The wear scars dimensions were in good agreement to clinical retrievals.

This study is the first that experimentally studied the wear behavior of ATSR based on clinical and biomechanical data under load controlled conditions. In term of wear the analyzed ATSR could clearly benefit from ceramic humeral heads. However, in comparison to experimental wear studies of total knee and hip replacements the wear rate of the studied ATSR was relatively high. Therefore further research may focus on optimized wear conditions of ATSR and the hereby described method may serve as a tool to evaluate a wear optimization process.