[Use of a water jet for synovectomy: in vitro study of feasibility]

AIM

The selectivity of a water jet (WJ) is already used with clinical advantage in the surgery of liver, brain, kidney and herniated lumbar discs. The aim of the present study was to determine whether a WJ can be used for synovectomy without damaging the joint capsule and the cartilage.

METHOD

60 human cadaver knee specimens (67 +/- 14 years) were dissected into synovial and cartilage samples. They were randomly assessed to four pressure groups (pW = 3; 6; 9; 12 MPa) and three jet surface angles (beta = 30; 60; 90 degrees) The nozzle diameter was dD = 0.12 mm, the stand off distance of the jet was s = 10 mm with a feed rate of vV = 2 mm/s. The acquired parameters were depth of the cuts, histological layer, and change of the samples thickness.

RESULT

There was a correlation of the cutting depth and the pressure (pW), whereas the jet-surface angle (beta) showed no correlation. The synovial layer of the cut likewise correlated with the pressure. At pW = 6 MPa the stratum subsynoviale could be cut selectively without damaging the fibrous capsule or the cartilage. The increase of the samples thickness was caused by an interstitial oedema.

CONCLUSION

The different mechanical properties of the joint capsule and the stratum subsynoviale lead to the selective cutting of the water jet. Since the joint capsule was not damaged, the feasibility of WJ synovectomy has been proven. The device can be used for synovectomy in parts of the joint that are not visible as well as in very small joints.

Side-effects of extracorporeal shock wave therapy (ESWT) in the treatment of tennis elbow

Apart from a few observational reports, there are no studies on the side-effects of extracorporeal shock wave therapy (ESWT) in the treatment of insertion tendopathies. Within the framework of a randomised, placebo-controlled, single-blind, multicentre study to test the effectiveness of ESWT in the case of lateral epicondylitis (LE), side-effects were systematically recorded. A total of 272 patients from 15 centres was allocated at random to active ESWT (3 x 2000 pulses, energy flux density ED(+) 0.04 to 0.22 mJ/mm(2) under local anaesthesia) or placebo ESWT. In all, 399 ESWT and 402 placebo treatments were analysed. More side-effects were documented in the ESWT group (OR = 4.3, CI = [2.9; 6.3]) than in the placebo group. Most frequently, transitory reddening of the skin (21.1%), pain (4.8%) and small haematomas (3.0%) were found. Migraine was registered in four and syncopes in three instances after ESWT. ESWT for LE with an energy flux density of ED(+) 0.04 to 0.22 mJ/mm(2) is a treatment method which has very few side-effects. The possibility of migraine being triggered by ESWT and the risk of a syncope should be taken into account in the future. No physical shock wave parameters could be definitely identified as the cause of the side-effects observed.