Between September 2002 and December 2004, 99 patients (> 18 years of age) underwent a diagnostic fluoroscopically-guided joint injection. Out of these 99 patients 25 patients were excluded from this study for the following reasons. Six patients who after surgery developed a non-union, thus compromising the outcome by other means than a correct or not correct indication for surgery were excluded. Five patients with contrast leakage, two with CRPS, and four patients with additional surgery were also excluded. Finally, eight patients were lost to follow-up. In patients with bilateral injections only the first injection was included [10]. Thus, 74 patients participated in the study. All patients had experienced foot complaints for more than 12 months and the majority of patients at the time of referral to our department had already been treated conservatively. Conservative treatment consisted mostly of modification of shoe wear or inlays. Pre-operative diagnoses included 39 patients with posttraumatic arthritis, 31 patients with osteoarthritis and 4 patients with rheumatoid arthritis.
All affected joints were injected by a skeletal oriented radiologist under fluoroscopic control (Philips BV300, The Netherlands) using an antiseptic technique and a standardized protocol [4, 11]. Confirmation of the intra-articular position of the needle was performed by use of 0.5-1 ml of contrast material (Omnipac 300, GE Healthcare, UK or Xenetix 300, Guerbet Group The Netherlands). The used anesthetic drug consisted of bupivacaine (Actavis Group, The Netherlands) 0.25% and citanest 1% (AstraZeneca BV, The Netherlands). Depending on the size and capacity of the joint the volume anesthetic drug ranged from 1.5 to 6 ml. Special attention was given to leakage of the fluid to connecting joint.
A Visual Analogue Score measuring pain (VAS) was obtained closely before and 30 minutes after the injection in rest and after exercise [12]. Foot Function Index (FFI) was obtained before the injection [13–15]. Two foot and ankle surgeons (JWL and BS) decided whether conservative or operative treatment was advised to a patient. This advise was based on history, physical examination and additional information acquired through X-ray examination, CT scans and furthermore a substantial difference in VAS scores before and after the injections. Based on the literature [2, 12] and clinical experience a dVAS of 3 or more was determined as the minimum effect of the diagnostic injection in order to regard this as a positive parameter to advise surgery. Subjective criteria such as the involvement in law suits, workers compensation issues, and pain behavior were taken into account also.
Four groups were distinguished and analyzed in this study:
Group 1: Preoperative successful anesthetic injection resulting in successful surgery (34 patients). In this group there was a positive result on injection resulting in a VAS decrease of at least 3 points. Based on the effect of the diagnostic injection and various clinical factors the doctor would advise surgery and the patient agreed to have surgery. The VAS postoperative was at least three points lower than preoperatively. This group seems to show an association between positive result on injection and success after surgery.
Group 2: Preoperative successful anesthetic injection and refusal to surgery (19 patients). This group consists of patients who had a successful preoperative anesthetic injection with a VAS decrease of at least 3 points and choose not to have surgery although they were advised to. No significant improvement was seen from conservative treatment in this group.
Group 3: Preoperative unsuccessful anesthetic injection but surgery anyway (six patients).
In this group the unsuccessful injection did not deter the doctor or the patient from surgical intervention. These patients did actually gain from the surgery as their VAS decreased more than three points, a significant decrease. This would argue against our hypothesis that preoperative anesthetic injection would predict the result of surgery.
Group 4: Preoperative unsuccessful anesthetic injection and no surgery (15 patients). This is the group in which the negative result to anesthetic injection resulted in the decision not to operate. No significant improvement was seen from conservative treatment in this group.
After a mean follow-up of 3.6 years (range 2.1 to 4.3 years), all patients were requested to complete a VAS for pain in rest and after exercise and the FFI. The conservative group was asked if they had undergone surgery elsewhere during the follow-up period and if they were using any kind of foot/ankle orthotics or shoe adaptations. When complications such as non union occur after surgery the VAS for pain and FFI measurements are gravely influenced and it was decided not to include these patients in the study to prevent a bias. Thus these patients were excluded from the study as mentioned earlier.
Wilcoxon signed rank tests and Mann Whitney U tests were used for statistical analysis. We evaluated whether pain reduction after intra-articular anesthetic drug injection could be indicative for a successful outcome (i.e. pain and function) of arthrodesis or conservative treatment in foot and ankle pathology. The local hospital review board granted permission for this study. Ethical approval was not required for this study.
