Temperature evaluation during PMMA screw augmentation in osteoporotic bone—An in vitro study about the risk of thermal necrosis in human femoral heads

Abstract

The use of polymethylmethacrylate (PMMA) bone cement to augment hip screws reduces cut-out risk but is associated with an exothermic reaction. This in vitro investigation evaluated the risk of thermal necrosis when augmenting the implant purchase with PMMA. A pilot study analyzed the effects of different PMMA layer thicknesses on temperatures around an implant. The main study used either 3.0 or 6.0 cc PMMA for hip screw augmentation in human femoral heads. The risk of thermal necrosis was estimated according to critical values reported in literature. Highest temperatures were measured inside the PMMA with a significant drop of average maximum temperatures from the center of the PMMA to the PMMA/bone interface. Risk of thermal necrosis exists with PMMA layer thicknesses greater than 5.0 mm. In the main study, we found no risk of thermal necrosis at the PMMA/bone interface or in the surrounding bone, neither with 3.0 nor 6.0 cc PMMA. The results of the two studies were consistent regarding average peak temperatures related to associated cement layer thicknesses. The results of this in vitro study reduce objections concerning the risk of thermal necrosis when augmenting cancellous bone around hip screws with up to 6.0 cc PMMA.

Long-term results of the augmented PFNA: a prospective multicenter trial

“…The same study also showed that the reached temperature is dependent on the amount of injected cement. For the present study, a lower amount of cement was used (mean 3.8 ml) and it is assumed that this amount does not lead to negative impact on both bone and cartilage as previously described [4,43]. Our findings that there were no radiological signs of osteonecrosis at follow-up and that there was no significant change of the joint space support this statement.…”

“…The main concerns about such a device were a potential disturbance of bone metabolism [14,19,37] and the induction of cartilage damage although there are several investigations rebutting this [4,41,43]. The current prospective multicenter trial was conducted to evaluate the long-term clinical outcome as well as the radiological results with the standardized augmentation of the PFNA.…”

Standardised cement augmentation of the PFNA using a perforated blade: A new technique and preliminary clinical results. A prospective multicentre trial

“…This supports the theory that there is no thermal damage to the bone due to the exothermic reaction of the PMMA in a standardised augmentation setting with only a small amount of cement injected. 26,28 The mean cement volume of 4.2 ml used in our study was able to increase stability in biomechanical investigations. 14,20,23,26 However, with this small amount of cement damage to the bone is unlikely.…”

“…26,28 The mean cement volume of 4.2 ml used in our study was able to increase stability in biomechanical investigations. 14,20,23,26 However, with this small amount of cement damage to the bone is unlikely. 14 In this context, it has to be mentioned that our follow-up time could be too short for a statement about bone necrosis, as several authors report the time to onset up to 3 years after the fracture.…”

“…13,23,24 However, several studies report no damage to the cartilage or the bone itself by cement augmentation. [25][26][27][28] The current prospective multicentre study was undertaken to evaluate the early clinical results and the technical performance of the new standardised augmentation for the PFNA blade. To our knowledge, this is the first report on this device.…”