Measurement of oxygen partial pressure in the mandibular bone using a polarographic fine needle probe.

In this study, the oxygen partial pressure in the cancellous bone substance of the mandible was measured for the first time with a polarographic fine needle probe. This has so far only been established in soft tissue. The aim was to prove and to test the feasibility in principle of this method of measurement in order to ascertain the normal values for the O2 partial pressure in healthy bone. These values were afterwards compared with the results of measurements in areas of different pathological bone conditions in order to assess the clinical suitability of the method for "mapping" during mandibular resection. Measurements of oxygen partial pressure were made in a total of 42 patients (16 women, 26 men). Of these, 12 patients with clinically normal bones served as a control group. Seventeen patients had osteoradionecrosis following radiation treatment, and 13 patients presented with chronic osteomyelitis of the mandible. All measurements were carried out with a polarographic fine needle probe applied to the cancellous bone substance. The statistical analysis included a comparison of the mean values of the oxygen partial pressures measured. No statistical correlation between oxygen partial pressure and pH and hemoglobin values could be detected. The average oxygen partial pressure in the healthy mandibular bone was 71.4 mmHg. In non-healthy bone, the value fell to an average of 30.6 mmHg (osteoradionecrosis 32.3 mmHg, chronic osteomyelitis of the mandibular bone 28.4 mmHg). Statistically, the differences in the group values ascertained were highly significant (P < 0.005). The data found show that this method can be successfully used to detect poorly perfused bone. The values are reproducible and reflect the clinical situation. In the long term, the method appears to be a suitable diagnostic tool for assessing the oxygen supply in bone in studying various clinical problems related to bone surgery.