gms | German Medical Science

Objective: Falls among elderly people and their consequences play an important (medical and financial) role for preventive medicine and rehabilitation [1]. Pajala et al. [2] showed an interconnection between higher CoP-movements and increased risk of falls on the basis of static balance evaluations. Patients with total arthroplasty of the hip (THA) or knee (TKA) show limitations in their stand stability due to muscular deficiencies and restrictions. Besides various studies regarding balance and stand stability in healthy people, only little data has been published concerning arthroplasty patients. Therefore it was the objective of this investigation to present a standardized test assembly including reference data of 112 hip and knee arthroplasty patients as a basis for stand stability evaluation.

Material/Methods: 112 patients (59♀, 53♂; 69±9a; 173±9cm; 81±16kg, THA n=67, TKA n=45) participated in this study. Evaluation of stand stability was assessed by means of a standardized test assembly with progression in the level of difficulty. At all times patients and test manager could interrupt the measurements due to safety or pain. The test assembly consisted of three parts: (1) Rombergtest (feet in comfortable, parallel stance; arms crossed and hands on opposite shoulder) with eyes open (REO) and eyes closed (REC); (2) Semitandem stand with left (STL) and right foot (STR) back (Hallux of posterior foot in contact with medial area of the calcaneus of the anterior foot; arms stretched out forward); (3) One legged stance on the left (EBL) and right (EBR) foot (arms in position as in REO and REC). All conditions were tested over a period of 20 sec [3] during which the patients were instructed to stand as still as possible. Pressure distribution was recorded by pressure plate (DIERS pedoscan) at 25 Hz and the CoP sway was determined. Absolute CoP length was calculated as a measure of stand stability. One-way ANOVA was performed with level of significance at 5 % (α=0,05; Bonferroni correction).

Results: All 112 patients accomplished REO and REC, 75 % achieved STL/R and only 14 % managed EBL/R. This increasing difficulty in the test assembly can also be represented by total CoP length (Figure 1 [Fig. 1]), which discriminates between test levels (p<0,001). Furthermore results of the achieved test level can be discriminated by total CoP length of REO (p=0,03) and REC (p<0,001). Post Hoc comparisons showed for total CoP length of REO differentiability only between levels REO/C and EBL/R (p=0,029), but for total CoP length of REC between levels REO/C and STL/R (p=0,003) as well as between REO/C and EBL/R (p<0,001). No difference was found between level STL/R and EBL/R at this parameter.

Conclusion: The examined balance test assembly shows, by virtue of its increasing level of difficulty, applicability in the classification of stand stability in THA and TKA patients. If necessary there is a shorter classification with bipedal stand and open eyes, by way of REO possible, distinguishing only between the groups achieving REO/C and EBL/R. There is also the possibility to reduce test procedure but discriminate between all three test levels by only accomplishing REC and identifying the different level achieving groups by total CoP length. Further investigations should extend the number of examined parameters. Collected data serve as a reference data base and shall be extended by future evaluations regarding stability values at earlier and later stages.