PURPOSE: Testing an applicable intraoperative system for measuring surface pressure in knee joints, simulating as accurately as possible operating theatre conditions. TYPE OF STUDY: Cadaver study. METHODS: Pressure probes were introduced into the knee joints medially and laterally (K 6900 quad probes) in five cadavers, providing real-time data with computerized data recording (K-scan system, manuf. Tekscan Inc., South Boston, MA). The initial position of the knee was flexed and hanging, as in a leg holder. In simulation of usual operating theatre procedures, the knee was manually extended to 0 degrees and again brought to hanging position. The data are given as relative-pressure values and should serve as the basis for intraoperative use. During arthroscopy, absolute-pressure values would then be influenced by the pressure of the arthroscopy pump. RESULTS: In 90 degrees flexion the average pressure ratio between the medial and lateral joint compartments was initially 1:1.5. When the leg was brought to full extension the pressure in the medial compartment increased, giving a pressure ratio of 1:1 at about 15 degrees and 1.8:1 at full extension. When bringing the leg back again to 90 degrees a similar pressure ratio curve was recorded. CONCLUSIONS: The pressure relationship between the medial and lateral knee compartments could be recorded and was found reproducible in simulated operating-theatre conditions. The measurement of joint surface pressure during implantation of an anterior cruciate ligament graft could provide data for individual intraoperative quality control, thus improving surgical results.
PURPOSE: Testing an applicable intraoperative system for measuring surface pressure in knee joints, simulating as accurately as possible operating theatre conditions. TYPE OF STUDY: Cadaver study. METHODS: Pressure probes were introduced into the knee joints medially and laterally (K 6900 quad probes) in five cadavers, providing real-time data with computerized data recording (K-scan system, manuf. Tekscan Inc., South Boston, MA). The initial position of the knee was flexed and hanging, as in a leg holder. In simulation of usual operating theatre procedures, the knee was manually extended to 0 degrees and again brought to hanging position. The data are given as relative-pressure values and should serve as the basis for intraoperative use. During arthroscopy, absolute-pressure values would then be influenced by the pressure of the arthroscopy pump. RESULTS: In 90 degrees flexion the average pressure ratio between the medial and lateral joint compartments was initially 1:1.5. When the leg was brought to full extension the pressure in the medial compartment increased, giving a pressure ratio of 1:1 at about 15 degrees and 1.8:1 at full extension. When bringing the leg back again to 90 degrees a similar pressure ratio curve was recorded. CONCLUSIONS: The pressure relationship between the medial and lateral knee compartments could be recorded and was found reproducible in simulated operating-theatre conditions. The measurement of joint surface pressure during implantation of an anterior cruciate ligament graft could provide data for individual intraoperative quality control, thus improving surgical results.