PURPOSE: A new device for intraoperative pedography was developed. The purpose of this study was to validate the introduced method with standard dynamic pedography, and to analyze the clinical benefit.

Methods: For an intraoperative introduction of standardized forces to the footsole, a device named Kraftsimulator Intraoperative Pedographie was developed.

The validation was performed in two steps: Step 1. Comparison of standard dynamic pedography (three trials, walking, third step, three trials, mid stance force pattern), static pedography in standing position (three trials) and pedography with KIOP in healthy volunteers (three trials, total force 400 N).. Step 2. Comparison between pedography in standing position, pedography with KIOP in awake and anaesthesized patients (three trials, total force 400 N).

A randomized prospective controlled study comparing treatment with and without intraoperative pedography has started on November 1, 2005. The subjects are randomized into two groups,

a) use of intraoperative pedography, versus

One-year-follow-up including standard dynamic pedography is planned. The following scores are used: American Orthopaedic Foot and Ankle Society (AOFAS), Visual-Analogue-Scale Foot and Ankle (VAS FA), Short-Form 36 (SF36, standardized to 100-point-maximum). Intraoperative consequences after the use of intraoperative pedography were recorded.

Results: Validation Step 1: 30 individuals were included (age, 26.1±8.6 years; gender, male: female = 24: 6). Step 2: 30 individuals were included (age, 55.3±30.3 years; gender, male: female = 24: 6). No significant differences between all measurements of step 1 and 2 were found for step 1 and 2 without the dynamic platform measurements of step 1.

Clinical use: 16 patients were included until January 31, 2006 (ankle correction arthrodesis, n=2; subtalar joint correction arthrodesis, n=4; arthrodesis midfoot, n=4, correction forefoot, 4; Lisfrcan-fracture-dislocation, n=2). 9 patients were randomized for the use of intraoperative pedography. The mean preoperative scores were: AOFAS: 49.6±23.7; VAS FA: 42.2±13.1; SF36: 48.1±23.2. The mean interruption of operative procedure for the intraoperative pedography was 359±34 seconds. In 4/9 cases changes were made after intraoperative pedography during the same operative procedure (correction modified, n=3; screw tightened, n=1). The follow-up has not been completed so far.

Conclusion: Since no statistical significant differences were found between the measurements of intraoperative pedography in anaesthesized individuals and the standard static pedography, the introduced method can be considered to be valid for intraoperative static pedography.

During the clinical use, in 44% of the cases a modification of the surgical correction were made after intraoperative pedography in the same surgical procedure.

Background Context: One of the main postulated basic principles of total disc replacement (TDR) is the preservation of flexion/extension ability. In neutral position the ideal disc prosthesis should not stay in maximal possible extension which would imply an impingement of the prosthesis. An impingement would cause shear strains on the prosthesis endplates which probably accelerate loosening. Moreover an additional extension ability from the neutral position would indicate no impingement in the facet joints in neutral position and a physiological movement capability.

Purpose: The purpose of study was to evaluate a possible impingement of the prosthesis or facet joints after TDR in neutral position.

Study design: Prospective evaluation of radiological outcome measures after total disc replacement.

Patient sample: The patients (19 female, 10 male) ranged from 29 to 56 years of age (mean: 42.46.5 years). The mean follow up interval averaged 13.2 months (range: 6 – 35 months). The diagnosis of degenerative disc disease was confirmed by MRI (black disc) and discography (positive „Memory pain“). Pain relief after facet joint infiltration was an exlucsion criteria. All patients had a single-level disc replacement (Prodisc II, Spine Solutions) with the same angulation (6).

Outcome measures: Evaluation of a possible impingement of the prosthesis and impingement of facet joints in neutral position.

Methods: A computer based analysis of pre- and postoperative lateral X-rays in neutral position and dynamic x-rays. The angulation of prosthesis in neutral position and the extension ability in dynamic x-rays were measured.

Results: 15 patients showed no extension ability on dynamic x-rays and 10 of these 15 patients had an impingement with maximum extension of the prosthesis on x-rays in neutral position. In the remaining 14 patients the extension ability averaged pre-/postoperatively 2.3/1.3 (p=0.115). In 4 of the 14 patients the pros-thesis showed an impingement in maximum extension and in 10 patients the prosthesis was not in maximum possible extension.

Conclusion: Due to the constrained design of the Pro-Disc an impingement is possible and was recognized in nearly 30% of the cases. The imbalance of flexion vs extension bending moments with increase in extension bending moments due to resection of the anterior longitudinal ligament and anterior anulus seems to be a possible explanation. It still remains unclear if an impingement will result in facet joint protection or will trigger a loosening of the implant. A prosthesis design which preserves the anterior longitudinal ligament would be probably a possible solution.

Introduction: Analgesia from controlled injections of local anaesthetic into the lumbar zygapohysial joint (z-joint) has been accepted as the standard for diagnosis of z-joint pain. Little is known about the placebo-response rate. Aim of this pilot study is to validate the fluoroscopically controlled z-joint-injection (ZJI) as an instrument for diagnosis of degenerative symptomatic z-joint disease.

Material and Methods: Due to degenerative lumbar spine syndrome 50 z-joints (L5/5: 27; L5/S1 23) were injected three times in a single blinded trial bilaterally. According to a randomisation protocol, using the oblique needle technique the ZJI were done with an local anaesthetic (LA: 1.5 ml 0.5% Scandicain), a saline placebo (sodium: 1.5ml 0.9% NaCl) and with no agent (sicca punction). The pain level before and after the injections (30 min, 1 and 2–3 hours) was documented by the patient on a 10pts.-VAS. Improvement in the pain level after an FJI is defined as responder. A responder reacts false positive if the degree of effectiveness of the placebo-FJI is the same or better than the response to LA. A patient reacts false negative if the pain diminution after LA application is lower than after placebo.

Results: Preliminary results regarding the reactions 30 min after injection are presented. 26% were non-responder and 52.9% LA-responder. The sicca response rate was 38%, for sodium it was 46%. Reaction after sicca-FJI was false positive in 24%, after sodium-FJI in 32% of cases. 38% reacted false negative to LA-injection. The order of the agent application didn’t have significant influence on the responder rates and also not on the extent of contradictory effects.

Conclusions: Despite numerous examinations none could sufficiently evaluate accurate reliable predictors for positive ZJI-responders till now. This is confirmed by our high LA-non-responder-rate of 48.1%. However, only a placebo injection can absolutely exclude a true placebo response. Placebo responses seem to be common. High specificity (minimization of the false positive results) and sensitivity (minimization of the false negative results) are characters for a good diagnostic test. In literature, the specificity of the intraarticular facet block as a diagnostic test for facet joint disease is currently unknown. Capsular rupture with epidural and periarticular diffusion is probably responsible for many false positive findings. Regarding our results, the validity of only one ZJI is not acceptable and shouldn’t be consulted as a diagnostic method for the identification of a facet joint syndrome, therefore. Pain relief after ZJI is a poor predictor of clinical outcome of posterolateral lumbosacral fusions when based on single blocks. Corresponding further examinations are necessary also regarding the ZJI-reliability.

Background Context: Total disc replacement (TDR) gained enormous popularity as a treatment option for symptomatic degenerative disc disease in the last few years. But the impact of the prosthesis design on the segmental biomechanics in most instances still remains unclear. As TDR results in a distraction of the capsuloligamentous structures, the disc height seems to be of crucial importance for the further biomechanical function of the operated level. Yet the biomechanical role of disc height after TDR still remains unclear.

Purpose: The purpose of study was to evaluate the influence of prosthesis height after total disc replacement on: 1) the sagittal balance and 2) the range of motion.

Study design: A radiological and an in-vitro biomechanical study.

Method: 6 human, lumbar spines L4–L5 were tested in vitro.The segmental lordosis of the specimen were measured on plain radiographs and the range of motion was measured for all six degrees of freedom with a previously described spine tester. The segmental lordosis and the range of motion at level L4–L5 was evaluated for following settings: 1) intact state 2) after implantation of a prosthesis with 5mm endplate 3) after implantation of a prosthesis with 7mm endplate.

The prosthesis used was a prototyp and had a constrained design with a ball and socket principle.

Results: Even the implantation of the lowest possible prosthesis height (5mm endplate) resulted in an increase of segmental lordosis (intact: 6.9; 5mm endplate: 8.8; p=0,027). Using a higher prosthesis (7mm endplate) further increased the segmental lordosis (10.5, p=0.041). The implantation of the lowest prosthesis resulted in significant increase of movement capability compared to the intact status for flexion-extension (8.6 vs 11.4; p=0.046) and axial rotation (2.9 vs 5.1; p=0.028). Lateral bending did not changed significantly (9.4 vs 8.6; p=0.345). The implantation of the higher prosthesis (7mm endplate) resulted in similar movement capability compared to intact status for flexion-extension (8.4 vs 8.6; p=0.116) and axial rotation (3.3 vs 2.9; p=0.600). Lateral bending decreased significantly compared to the intact status (5.1 vs 8.6; p=0.028).

Conclusion: Total disc replacement with the lowest prosthesis height inherently increases segmental lordosis. Further increase of disc height results in a significant enhancement of segmental lordosis by decreasing the range of motion for all three degrees of freedom. Yet, methods for scheduling the ideal disc height preoperatively, to provide a physiological lordosis thereby maintaining physiological range of motion postoperatively, seems not to be established already.