Whereas thermography has already been used as an assessment of disease activity in some kinds of inflammatory arthritis, it is a new method for objektive pain evaluation in patients with joint prosthesis. To our knowledge, no study has tested the correlation between increase of temperature and anterior knee pain with total knee prosthesis yet.

Thirteen patients were included in this study who suffered from anterior knee pain of the retinaculum patellae with total knee prosthesis. The patients were asked to walk 3 km before entering a room which was cooled down to 20 degrees Celsius. A black 1 cm times 4.5 cm square stripe was attached on the diameter of the patella and the patients rested for 20 minutes to cool down before thermographic fotos were taken from 90 degrees, 45 degrees, frontal medial and lateral. The evaluation of temperature difference of each side was performed by marking a 1cm times 2cm square field rectangular around the black stripe and comparing it with a reference point of the same size 3 cm distal of the field. The patients were compared with thirteen others, not suffering from anterior knee pain. Statistical analysis was performed using a t- test and a p value < 0.05 was considered to be significant.

The temperature differences between the rectangular field and the reference point increased significantly on the medial (p= 0.00037) or lateral (p= 0.000002) pain side of the knee. The thirteen knees with knee pain had significantly higher temperature differences between medial and lateral temperature differences, than the knees without knee pain.

We demonstrate a significant correlation between anterior knee pain and an increase of superficial skin temperature around the retinaculum patellae. To our knowledge, this is the first report of an objective assessment of pain of the retinaculum patellae with total knee prosthesis.

Purpose: The purpose of this work was to study the reliability and the precision of a lumber vertebra reconstruction method using images obtained from a 3D statistical model and two calibrated radiograms. The technique is designed for surgical approach to the lumbar spine and implantation of osteosynthesis material using enhanced-reality technology.

Material and methods: A lumbar vertebra was reconstructed on several specimens using images issuing from a 3D statistical model and two calibrated radiograms. The images obtained from the model of this lumbar vertebra to be reconstructed constituted the preoperative images. Intra-operative images corresponded to two calibrated radiograms acquired with a fluoroscope using advanced technology (silicium receptor). The model was equipped with reflecting patches which can be detected in space using a 3D optical system. Correspondence between the 3D statistical model and the two calibrated radiograms was achieved with appropriate software. Navigation views were displayed on the screen to guide surgical tools at the vertebral level. Pedicular screws were implanted into several anatomic specimens to evaluate the reliability and precision of the system. The exact position of the implanted screws was established with computed tomography.

Results: This system demonstrated its reliability and precision for the reconstruction of a lumbar vertebra from a 3D statistical model and two calibrated radiograms. All the implanted screws were perfectly positioned in the pedicles. Precision was to the order of 1 mm.

Discussion: This method is a passive system not requiring intraoperative intervention. Reconstruction of a lumbar vertebra from a preoperative 3D statistical model and two intra-operative calibrated radiograms avoids the need to identify anatomic landmarks and/or surface points on the vertebra to be reconstructed. The level of precision is very similar to that obtained with CT-based systems. Preoperative CT is not needed for navigation.

Conclusion: With this system, new generation fluoroscopic equipment should appear in the operating room, allowing acquisition of successive calibrated images. The digital data could then be matched with statistical anatomic data, avoiding the need for preoperative imaging (CT or MRI). Progressive introduction of intra-operative ultrasound to replace the calibrated radiograms should open a new approach for percutaneous surgery of the lumbar spine.

Purpose: A new software based on computed tomography data has been developed for individual unicompartmental reconstruction. The puropse is to achieve custom-made anatomic reconstruction of the medial compartment of the knee and to restore the physiological kinetics of each specific knee. This system can also be used to provide individualised tools for implantation

Material and methods: Custom-made unicompartmental prostheses and their corresponding implantation patterns were designed by this software. The data were fed to a rapid prototyping machine to produce a two-piece (cobalt-chromium and polyethylene) unicompartmental prosthesis and the guides for anatomic cuts specific for each knee. This method was tested on ten cadaver specimens in order to verify the precision of the reconstruction and alignment. A specially designed software was used to establish 3D reconstructions of the knee specimen taking precisely into account the cartilage surfaces. Virtual bone cuts were established to obtain the future seat for the implant. The data of the virtual bone cut were recovered to obtain a brute form of the future implant. The joint surfaces which still presented the degenerative lesions were repaired and finalised by interpolation and by use of the mirror data obtained from the contralateral knee. An individual support system was then installed to perform the bone cuts established virtually. The final data were then fed to a rapid prototyping machine and the aleasing machine to produce a two-piece unicompartment prosthesis and the guides for the anatomic cuts specific for each knee. The operation was then performed via a medial parapatellar 8cm incision. The implants were inserted without other fixation onto the knees and tested immediately to determine function. Anatomic reconstruction of the knee was checked with standard x-rays and CT images compared with the initial data.

Results: The implants could be inserted rapidly and easily. The impact of exhibited an excellent press fit and reproduced the initial morphology of the healthy articulation.

Discussion: Movement of the knee prosthesis reproduced all the characteristic physiological movements. Furthermore, the knee prosthesis obtained with this method allowed individualised and minimalised bone cuts, optimising congurency and contact zones between the bone and the implant and thus reducing the difficulties of surgical alignment. This system appears to offer high-performance restoration of individual physiological joint kinetics.

Purpose: No conventional surgical technique for ligament reconstruction can be used in all cases to achieve ideal position of the transplant. Navigation systems without visualisation of the anterior cruciate ligament should meet the requirements. This is an operative strategy based on one or more computer assisted procedures enabling ligament reconstruction without the need for conventional pre- per, or postoperative imaging. The principle is based at the present time on the use of a station (computer, localisers, display screen, command pedal) used for processing data (spatial measurements and positioning) delivered by markers fixed on rigid bodies and tools (palpation, aiming tools).

Material and methods: This study was conducted on ten cadaver knees. Each knee was instrumented with the station. Joint kinetics were recorded with and without the ACL and after harvesting the transplant: patellar ligament and hamstring ligaments. Bone morphing was used to draw the tibial and femoral surfaces. Two types of aiming tools were tested by recording the data points issuing from the tibial output and the femoral input. The position of the femoral and tibial holes was determined to achieve the smallest anisometry and absence of notch conflict. Isometric zones were compared with the anatomic zones of the ACL. We also compared the position of the transplant determined by the computer and that determined according to the methods of conventional arthroscopy. An x-ray of each knee was obtained to compare with data in the literature concerning the advised position of the femoral and tibial holes with that established by the computer navigation system. Each knee was tested with KT1000 before and after surgery.

Results: The precision of bone morphing was 0.1 mm. Anisometric curves were compatible with drilling holes calibrated to the size of the implant in four knees. The operator used the navigation system to determine the point of the femoral hole in six knees. The system then calculated the point of the tibial hole automatically eliminating the risk of notch conflict. The anisometric values were less than 2 mm; the distance roof of the notch/anterior border of the transplant was calculated as a function of the radius of the transplant (3.5–5 mm). The position of the tibial hole given by the computer system was always more medial than that given by the tibial aiming tools. The position of the femoral tunnel was always more anterior than that given by the femoral aiming tools. The postoperative KT1000 values were identical to the preoperative values.

Discussion: Navigation without visualisation of the ACL is able to position the ACL in an isometric plane or better in an “anatomometric” plane, to inscribe the joint orifice of the tibial hole on the projection of the anterior arch of the notch on the tibial surface, to draw in real time the isometric femoral map on the notch in order to centre the joint orifice of the tibial hole as well as the corresponding laxity map, to indicate on the femoral notch the point which will be the centre of the joint orifice of the femoral hole, to draw the isometric curve of a given fibre and its corresponding laxity map, and to detect and allow the treatment of any transplant-notch conflict.

Purpose: This prospective comparative study examined the two-year results of two femoral fixation method for anterior cruciate ligament (ACL) repair using the four-part hamstring technique. A consecutive series of 60 patients with the same tear criteria involving the ACL alone were randomly assigned to the two treatment arms. Femoral fixation was achieved by mixed corticocancellous transfixation or by interference screw fixation.

Material and methods: The series included two cohorts of 30 patients each. We excluded patients with a history of ligament or bone surgery and those with associated lesions of the peripheral ligaments. Complementary lateral reinforcement was not performed in either group. The interference screw fixation group had 20 men and 10 women, mean age 29 years (14–48), 18 right side. The blind femoral tunnel was drilled arthroscopically. The transfixation group included 19 men and 11 women, mean age 26 years (16–40), 17 right side. The blind femoral tunnel was drilled via a transtibial approach using the Rosenberg aiming procedure. In both cohorts, tibial fixation of the transplant was achieved with a resorbable polylactic screw measuring at least the diameter of the tibial tunnel. Statistical analysis of results (Statview 4.5) was based on the clinical IKDC score, thigh volume, and level of sports activity. Telos at 15 and 20 kg was used to measure laxity.

Results: Mean delay to review was 24 months (22–26). The two cohorts were comparable preoperatively (laxity, sports level, meniscal or cartilage lesions). There was no statistical difference for joint amplitudes, joint instability, or level of sports activity at last follow-up. The telos differential laxity at 15 kg was statistically lower in the interference screw fixation group (mean 1.1 mm) than in the transfixation group (mean 1.4 mm) (p < 0.01). There were no complications in either group, particularly no cyclope syndrome. Radiographically, there was no statistical difference for the position of the tibial tunnel. The femoral tunnel was however different: the Aglietti index was 0.57 for transfixation and 0.62 for interference screw fixation (p < 0.01).

Discussion: This prospective study demonstrated the good mid-term anatomic results after 4-part hamstring plasty of the ACL for both types of femoral fixation (transfixation or interference screw fixation). The position of the femoral tunnel appeared to be better with interference screw fixation, with a statistical correlation with better anatomic results (telos). This suggests that the transtibial femoral aiming procedure does not necessarily produce a totally satisfactory isometric alignment.