Improvements in pain, function and sports activity are the main goals of patients following total knee arthroplasty (TKA). Participation in sports has become an increasingly important contributor to patients' quality of life (QoL). Hiking is one of the most popular summer activities among elderly people in alpine regions. Consequently, this randomized controlled trial investigates the impact of a 3-month guided hiking programme on patients' functional abilities and QoL following TKA. It was hypothesized that patients who participate in this programme would demonstrate improvements in functional and QoL parameters compared with a control group.

Forty-eight TKA patients were included and randomized into either the intervention group (IG; n = 25) or the control group (CG; n = 23). The IG participated in a 3-month hiking programme (2-3 times a week), whereas the CG performed activities of daily living. The stair climb test (SCT), QoL questionnaires and isokinetic force measurements were completed at three time points (i.e. pre-test, post-test, retention-test). ANOVAs for repeated measurements were conducted for the SCT results. The Friedman test and the Mann-Whitney U test were performed for the QoL parameters.

After the 3-month hiking programme, the IG achieved faster overall walking times on the SCT. The time decreased from 4.3 ± 0.6 s (pre-test) to 3.6 ± 0.4 s (post-test) for the stair ascent (p = 0.060) and from 3.6 ± 0.6 s (pre-test) to 3.2 ± 0.5 s (post-test) for the stair descent (p = 0.036). The IG showed significant improvement on some of the subscales of the Knee Injury and Osteoarthritis Outcome Score from pre-test to retention-test (p < 0.01). In the CG, no significant changes were observed (n.s.).

The results indicate moderate improvement in the functional abilities and QoL of TKA patients who participated in a 3-month guided hiking programme compared with the patients in the CG. Hiking did not have any acute detrimental effects on the TKA patients during this study period.

II.

In a retrospective study with a population over 65 years, sports activity was conducted 6 years after cruciate retaining (CR) total condylar knee arthroplasty (TKA) with rotating platform (RP). Eighty-one Patients (71.8±5.4years) were examined at follow-up 6.4±0.9 years postoperative. Sport was practiced 5.3 hours every week in mean. Patients were active in sports 3.5times per week. Twenty-five percent performed high impact sports, 47% medium impact sports and 52% low impact sports at follow-up. In KOOS sports 60±28 was reached, in WOMAC 12.1±15.1. It can be concluded that in this population 50% of patients were active in medium and low impact sport 6 years after surgery. However, a quarter of patients were also active in high impact sports.

Aseptic loosening and other wear-related complications are some of the most frequent late reasons for revision of total knee arthroplasty (TKA). Periprosthetic osteolysis (PPOL) pre-dates aseptic loosening in many cases, indicating the clinical significance of this pathogenic mechanism. A variety of implant-, surgery- and host-related factors have been delineated to explain the development of PPOL. These factors influence the development of PPOL because of changes in mechanical stresses within the vicinity of the prosthetic device, excessive wear of the polyethylene liner, and joint fluid pressure and flow acting on the peri-implant bone. The process of aseptic loosening is initially governed by factors such as implant/limb alignment, device fixation quality and muscle coordination/strength. Later, large numbers of wear particles detached from TKA trigger and perpetuate particle disease, as highlighted by progressive growth of inflammatory/granulomatous tissue around the joint cavity. An increased accumulation of osteoclasts at the bone-implant interface, impairment of osteoblast function, mechanical stresses and increased production of joint fluid contribute to bone resorption and subsequent loosening of the implant. In addition, hypersensitivity and adverse reactions to metal debris may contribute to aseptic TKA failure, but should be determined more precisely. Patient activity level appears to be the most important factor when the long-term development of PPOL is considered. Surgical technique, implant design and material factors are the most important preventative factors, because they influence both the generation of wear debris and excessive mechanical stresses. New generations of bearing surfaces and designs for TKA should carefully address these important issues in extensive preclinical studies. Currently, there is little evidence that PPOL can be prevented by pharmacological intervention.

The expectations of total joint replacement are constantly increasing: Freedom of pain and mobility used to be the primary goal, while nowadays it is longevity despite heavy loading and intense sporting activity. A preoperative sportive patient expects to be able to perform his favorite sporting activities like hiking, swimming and cycling, but also the more demanding skiing, tennis and jogging, for example, after surgery. The aim of this article is to illustrate what level of sporting activities can be performed by patients with total joint replacement. Are there differences between the pre- and postoperative levels? What are the risks for, and negative influences on, the prosthesis during intense sporting activity? What is the role of the physician? Finally, recommendations for sporting activities after total hip and knee replacement are given.

This article presents a literature review of the current recommendations regarding sports after total joint replacement and also suggests scientifically based guidelines. Patients should be encouraged to remain physically active for general health and also for the quality of their bone. There is evidence that increased bone quality will improve prosthesis fixation and decrease the incidence of early loosening. To recommend a certain activity after total knee or hip replacement, factors such as wear, joint load, intensity and the type of prosthesis must be taken into account for each patient and sport. It has been shown that the reduction of wear is one of the main factors in improving long-term results after total joint replacement. Wear is dependent on the load, the number of steps and the material properties of total joint replacements. The most important question is, whether a specific activity is performed for exercise to obtain and maintain physical fitness or whether an activity is recreational only. To maintain physical fitness an endurance activity will be performed several times per week with high intensity. Since load will influence the amount of wear exponentially, only activities with low joint loads such as swimming, cycling or possibly power walking should be recommended. If an activity is carried out on a low intensity and therefore recreational base, activities with higher joint loads such as skiing or hiking can also be performed. It is unwise to start technically demanding activities after total joint replacement, as the joint loads and the risk for injuries are generally higher for these activities in unskilled individuals. Finally, it is important to distinguish between suitable activities following total knee and total hip replacement. To recommend suitable physical activities after total knee replacement, it is important to consider both the load and the knee flexion angle of the peak load, while for total hip replacement, which involves a ball and socket joint, the flexion angle does not play an important role. During activities such as hiking or jogging, high joint loads occur between 40 and 60 degrees of knee flexion where many knee designs are not conforming and high polyethylene inlay stress will occur. Regular jogging or hiking produces high inlay stress with the danger of delamination and polyethylene destruction for most current total knee prostheses. Based on these design differences between hip and knee replacements it is prudent to be more conservative after total knee arthroplasty than after total hip arthroplasty for activities that exhibit high joint loads in knee flexion.