Introduction

Chronic ruptures of the quadriceps tendon after total knee arthroplasty (TKA) are rare but are a devastating complication. The objective of this study was to validate the use of fresh frozen total fresh quadriceps tendon allografts for quadriceps tendon reconstruction. The hypothesis of this work was that the graft was functional in more than 67% of cases, a higher percentage than the results of conventional treatments.

INTRODUCTION

Peri-prosthetic fungal infection is generally considered more difficult to cure than a bacterial infection. Two-stage exchange is considered the gold standard of surgical treatment. A recent study, however, reported a favorable outcome after one stage exchange in selected cases where the fungus was identified prior to surgery.

The routine one stage exchange policy for bacterial peri-prosthetic infection involves the risk of identifying a fungal infection mimicking bacterial infection solely on intraoperative samples, i.e. after reimplantation, realizing actually a one stage exchange for fungal infection without pre-operative identification of the responsible fungus, which is considered to have a poor prognosis. We report two such cases of prosthetic hip and knee fungal infection. Despite this negative characteristic, no recurrence of the fungal infection was observed.

CASE N°1: A 78 year old patient was referred for loosening of a chronically infected total hip arthroplasty (Staphylococcus aureus and Streptococcus dysgalactiae). One stage exchange was performed. Intraoperative bacterial cultures remained sterile. Two fungal cultures were positive for Candida albicans. Antifungal treatment was initiated for three months. No infection recurrence was observed at three year follow up.

CASE N° 2: A 53-year-old patient was referred for loosening of a chronically infected total knee prosthesis (Staphylococcus aureus methicillin susceptible, Klebsiella pneumoniae and Staphylococcus epidermidis). One stage exchange was performed. Intraoperative bacterial cultures remained sterile. Five fungal cultures were positive for Candida albicans. Antifungal treatment was initiated for three months. No infection recurrence was observed at two-year follow-up.

We are using a non image based navigation system on a routine basis for unicompartmental knee replacement (UKR). We prospectively studied 60 patients who underwent navigated minimally invasive UKR for primary medial osteoarthritis at our hospital between October 2005 and October 2006. We established a navigated control group of 60 patients who underwent conventional implantation of a UKA at our hospital between April 2004 and September 2005. There were 42 male and 78 female patients with a mean age of 65 years (range, 44–87 years). There were no differences in all preoperative parameters between the two groups.

The accuracy of implant positioning was determined using predischarge standard anteroposterior and lateral radiographs. The following angles were measured: femorotibial angle, coronal and sagittal orientation of the femoral component, coronal and sagittal orientation of the tibial component. When the measured angle was in the expected range, one point was given. The accuracy was defined as the sum of the points given for each angle, with a maximum of five points (all items fulfilled) and a minimum of 0 point (no item fulfilled). Our primary criterion was the radiographic accuracy index on the postoperative radiograph evaluation. All other items were studied as secondary criteria.

The mean accuracy index was similar in the two groups: 4.1 ± 0.8 in the study group and 4.2 ± 1.2 in the control group. 36 patients (60%) in the control group and 37 patients (62%) in the study group had the maximum accuracy index of five points. All measured angles were similar in the two groups. There were no differences between the percentages of patients in the two groups achieving the desired implant positions. Mean operating time was similar in the two groups. There were no intraoperative complications in either group. The groups had similar major postoperative complication rates during hospital stay (3% for both).

The used navigation system is based on an anatomic and kinematic analysis of the knee joint during the implantation. The modification of the existing software for minimal invasive approach has been successful. It enhances the quality of implantation of the prosthetic components and avoids the inconvenient of a smaller incision with potential less optimal visualization of the intra-articular reference points. However, all centers observed a significant learning curve of the procedure, with a significant additional operative time during the first implantations. The postoperative rehabilitation was actually easier and faster, despite the additional percutaneous fixation of the navigation device. This system has the potential to allow the combination of the high accuracy of a navigation system and the low invasiveness of a small skin incision and joint opening.

Revision total knee replacement (TKR) is a challenging procedure, especially because most of the standard bony and ligamentous landmarks used during primary TKR are lost due to the index implantation. However, as for primary TKR, restoration of the joint line, adequate limb axis correction and ligamentous stability are considered critical for the short- and long- term outcome of revision TKR. There is no available data about the range of tolerable leg alignment after revision TKR. However, it is logical to assume that the same range than after primary TKR might be accepted, that is ± 3° off the neutral alignment. One might also assume that the conventional instruments, which rely on visual or anatomical alignments or intra- or extra-medullary rods, are associated with significant higher variation of the leg axis correction, especially in cases with significant bone loss which prevents to control the exact location of the usual, relevant landmarks. Navigation system might address this issue.

We used an image-free system (ORTHOPILOT TM, AESCULAP, FRG) for routine implantation of primary TKR. The standard software was used for revision TKR. Registration of anatomic and cinematic data was performed with the index implant left in place. The components were then removed. New bone cuts as necessary were performed under the control of the navigation system. The size of the implants and their thickness was chosen after simulation of the residual laxities, and ligament balance was adapted to the simulation results. The system did not allow navigation for intra-medullary stem extensions and any bone filling which may have been required. This technique was used for 54 patients. The accuracy of implantation was assessed by measuring following angles on the post-operative long-leg radiographs: mechanical femoro-tibial angle (normal = 0°, varus deformation was described with a positive angle); coronal orientation of the femoral component in comparison to the mechanical femoral axis (normal = 90°, varus deformation was described with an angle < 90°); coronal orientation of the tibial component in comparison to the mechanical tibial axis (normal = 90°, varus deformation was described with an angle < 90°); sagittal orientation of the tibial component in comparison to the proximal posterior tibial cortex (normal = 90°, flexion deformation was described with angle < 90°).

Individual analysis was performed as follows: one point was given for each fulfilled item, giving a maximal accuracy note of 4 points. Prosthesis implantation was considered as satisfactory when the accuracy note was 4 (all fulfilled items). The rate of globally satisfactory implanted prostheses and the rate of prostheses implanted within the desired range for each criterion were recorded.

Limb alignment was restored in 88%. The coronal orientation of the femoral component was acceptable in 92% of the cases. The coronal orientation of the tibial component was acceptable in 89% of the cases. The sagittal orientation of the tibial component was acceptable in 87% of the cases. Overall, 78% of the implants were oriented satisfactorily for the four criteria.

The navigation system enables reaching the implantation objectives for implant position and ligament balance in the large majority of cases, with a rate similar to that obtained for primary TKA. The navigation system is a useful aid for these often difficult operations, where the visual information is often misleading.

Navigation systems are able to measure very accurately the movement of bones, and consequently the knee laxity, which is a movement of the tibia under the femur. These systems might help measuring the knee laxity during the implantation of a total (TKR) or a unicompartmental (UKR) knee replacement.

20 patients operated on for TKR (13 cases) or UKR (7 cases) because of primary varus osteoarthritis have been analyzed. Pre-operative examination involved varus and valgus stress X-rays at 0 and 90° of knee flexion. The intra-operative medial and lateral laxity was measured with the navigation system at the beginning of the procedure and after prosthetic implantation. Varus and valgus stress X-rays were repeated after 6 weeks. X-ray and navigated measurements before and after knee replacement were compared with a paired Wilcoxon test at a 0.05 level of significance.

The mean pre-operative medial laxity in extension was 2.3° (SD 2.3°). The mean pre-operative lateral laxity in extension was 5.6° (SD 5.1°). The mean pre-operative medial laxity in flexion was 2.2° (SD 1.9°). The mean pre-operative lateral laxity in flexion was 6.7° (SD 6.0°). The mean intra-operative medial laxity in extension at the beginning of the procedure was 3.6° (SD 1.7°). The mean intra-operative lateral laxity in extension at the beginning of the procedure was 3.0° (SD 1.3°). The mean intra-operative medial laxity in flexion at the beginning of the procedure was 1.9° (SD 2.6°). The mean intra-operative lateral laxity in flexion at the beginning of the procedure was 3.5° (SD 2.7°). The mean intra-operative medial laxity in extension after implantation was 2.1° (SD 0.9°). The mean intra-operative lateral laxity in extension after implantation was 1.9° (SD 1.1°). The mean intra-operative medial laxity in flexion after implantation was 1.9° (SD 2.5°). The mean intra-operative lateral laxity in flexion after implantation was 3.0° (SD 2.8°). The mean post-operative medial laxity in extension was 2.4° (SD 1.1°). The mean post-operative lateral laxity in extension was 2.0° (SD 1.7°). The mean post-operative medial laxity in flexion was 4.4° (SD 3.3°). The mean post-operative lateral laxity in flexion was 4.7° (SD 3.2°).

There was a significant difference between navigated and radiographic measurements for the pre-operative medial laxity in extension (mean = 1.4° – p = 0.005), the pre-operative lateral laxity in extension (mean = 2.6° – p = 0.01), the pre-operative lateral laxity in flexion (mean = 3.3° – p = 0.005). There was no significant difference between navigated and radiographic measurements for the pre-operative medial laxity in flexion (mean = 0.3° – p = 0.63). There was a significant difference between navigated and radiographic measurements for the postoperative medial laxity in flexion (mean = 2.5° – p = 0.004). There was no significant difference between navigated and radiographic measurements for the postoperative medial laxity in extension (mean = 0.3° – p = 0.30), the post-operative lateral laxity in extension (mean = 0.2° – p = 0.76), the post-operative lateral laxity in flexion (mean = 1.7° – p = 0.06). These differences were less than 2 degrees in most of the cases, and then considered as clinically irrelevant.

The navigation system used allowed measuring the medial and lateral laxity before and after TKR. This measurement was significantly different from the radiographic measurement by stress X-rays for pre-operative laxity, but not statistically different from the radiographic measurement by stress X-rays for post-operative laxity. The differences were mostly considered as clinically irrelevant. The navigated measurement of the knee laxity can be considered as accurate. The navigated measurement is valuable information for balancing the knee during TKR. The reproducibility of this balancing might be improved due to a more objective assessment.

Revision TKR is a challenging procedure, especially because most of the standard bony and ligamentous landmarks are lost due to the primary implantation. However, as for primary TKR, restoration of the joint line, adequate limb axis correction and ligamentous stability are considered critical for the short- and long-term outcome of revision TKR. There is no available data about the range of tolerable leg alignment after revision TKR. However, it is logical to assume that the same range than after primary TKR might be accepted, that is ± 3° off the neutral alignment. One might also assume that the conventional instruments, which rely on visual or anatomical alignments or intra- or extramedullary rods, are associated with significant higher variation of the leg axis correction.

We used an image-free system (ORTHOPILOT TM, AESCULAP, FRG) for routine implantation of primary TKA. The standard software was used for revision TKA. Registration of anatomic and kinematic data was performed with the index implant left in place. The components were then removed. New bone cuts as necessary were performed under the control of the navigation system. The size of the implants and their thickness was chosen after simulation of the residual laxities, and ligament balance was adapted to the simulation results. The system did not allow navigation for centromedullary stem extension and any bone filling which may have been required. This technique was used for 54 patients. The accuracy of implantation was assessed by measuring the limb alignment and orientation of the implants on the post-operative radiographs.

Limb alignment was restored in 88%. The coronal orientation of the femoral component was acceptable in 92% of the cases. The coronal orientation of the tibial component was acceptable in 89% of the cases. The sagittal orientation of the tibial component was acceptable in 87% of the cases. Overall, 78% of the implants were oriented satisfactorily for the five criteria.

The navigation system enables reaching the implantation objectives for implant position and ligament balance in the large majority of cases, with a rate similar to that obtained for primary TKA. The navigation system is a useful aid for these often difficult operations, where the visual information is often misleading. The navigation system used enables facilitated revision TKA.

Anterior cruciate ligament (ACL) reconstruction allows overall good results, but there is still a significant rate of failure. It is well accepted that the main reason for ACL reconstruction failure is a misplacement of tibial or femoral tunnels. Conventional techniques rely mainly on surgical skill for intra-operative tunnel placement. It has been demonstrated that, even by experienced surgeons, there was a significant variation in the accuracy of tunnel placement with conventional techniques. Navigation systems might enhance the accuracy of ACL replacement.

10 cadaver knees with intact soft-tissue and without any intra-articular abnormalities were studied. We used a non image based navigation system (OrthoPilot ®, Aesculap, Tuttlingen, FRG). Localizers were fixed on bicortical screws on the distal femur and on the proximal tibia. Both kinematic and anatomic registration of the knee joint were performed by moving the knee joint in flexion-extension and palpating relevant intra- and extra-articular landmarks with a navigated stylus. The most anterior, posterior, medial and lateral point of both tibial and femoral attachment of the ACL were marked with metallic pins. The navigated stylus was positioned on these points, and the system recorded its position in comparison to the bone contours. Subsequently, we performed conventional plain AP and lateral X-rays and a CT-scan, and measured the position of the pins in comparison to the bone contours. Finally, all measurements were made again with a caliper after disarticulating the knee joint. We calculated the center of the footprint as the mid-point between the four pins of both tibial and femoral attachment for each measurement technique. All measurements were expressed as percentages of the bone size to compensate for the different sizes.

There were no significant difference in the paired measurements of the location of the ACL footprints on both femur and tibia between anatomic, radiographic, CT-scan and navigated measurements. There was a significant correlation between the paired measurements of the location of the ACL footprints on both femur and tibia with either measurement techniques.

Anatomic measurement is the gold standard experimental technique for the positioning of the ACL foot-print, and CT-scan measurement is currently the gold standard technique in clinical situation. According to this reference, the position of ACL attachments on the tibia and on the femur can be accurately defined by the navigation system. Intra-operative measurement of the location of the bone tunnels during ACL replacement with this navigation system should be accurate as well.

Unicompartmental knee replacement (UKR) is accepted as a valuable treatment for isolated medial knee osteoarthritis. Minimal invasive implantation might be associated with an earlier hospital discharge and a faster rehabilitation. However these techniques might decrease the accuracy of implantation, and it seems logical to combine minimal invasive techniques with navigation systems to address this issue.

The authors are using a non image based navigation system (ORTHOPILOT ^™, AESCULAP, FRG) on a routine basis for UKR. We prospectively studied 60 patients who underwent navigated minimally invasive UKR for primary medial osteoarthritis at our hospital between October 2005 and October 2006. We established a navigated control group of 60 patients who underwent conventional implantation of a UKA at our hospital between April 2004 and September 2005. There were 42 male and 78 female patients with a mean age of 65 years (range, 44–87 years). There were no differences in all preoperative parameters between the two groups.

The accuracy of implant positioning was determined using predischarge standard anteroposterior and lateral radiographs. The following angles were measured: femorotibial angle, coronal and sagittal orientation of the femoral component, coronal and sagittal orientation of the tibial component. When the measured angle was in the expected range, one point was given. The accuracy was defined as the sum of the points given for each angle, with a maximum of five points (all items fulfilled) and a minimum of 0 point (no item fulfilled). Our primary criterion was the radiographic accuracy index on the postoperative radiograph evaluation. All other items were studied as secondary criteria.

The mean accuracy index was similar in the two groups: 4.1 ± 0.8 in the study group and 4.2 ± 1.2 in the control group. 36 patients (60%) in the control group and 37 patients (62%) in the study group had the maximum accuracy index of five points. All measured angles were similar in the two groups. There were no differences between the percentages of patients in the two groups achieving the desired implant positions. Mean operating time was similar in the two groups. There were no intraoperative complications in either group. The groups had similar major postoperative complication rates during hospital stay (3% for both).

The used navigation system is based on an anatomic and kinematic analysis of the knee joint during the implantation. The modification of the existing software for minimal invasive approach has been successful. It enhances the quality of implantation of the prosthetic components and avoids the inconvenient of a smaller incision with potential less optimal visualization of the intra-articular reference points. However, all centers observed a significant learning curve of the procedure, with a significant additional operative time during the first implantations. The postoperative rehabilitation was actually easier and faster, despite the additional percutaneous fixation of the navigation device. This system has the potential to allow the combination of the high accuracy of a navigation system and the low invasiveness of a small skin incision and joint opening.

Introduction: The accuracy of implantation is an accepted prognostic factor for the long term survival of a unicompartmental knee prosthesis (UKP). Minimal invasive technique is recommended for faster post-operative recovery. We developed an adaptation of a non image based system for either conventional or minimal invasive UKP implantation. We hypothesized that the used non image based navigation system will allow to place a UKP in the same position for both conventional and minimal-invasive approach.

Methods: 20 patients were operated on with this experimental minimal invasive navigated technique (group A) and compared to a group of 20 cases operated with the conventional navigated technique (group B), matched to the study group according to age, gender andseverity of the coronal deformation. Coronal mechanical femorotibial angle and coronal and sagittal orientation of the components were measured on post-operative antero-posterior and lateral long leg X-rays. The rate of satisfactory implanted prostheses was compared in both groups with a Chi-square test with a 0.05 limit of significance.

There was no significant difference in the pre-operative data between both groups. The post-operative coronal group A and 17 cases in group B. The prosthesis was optimally implanted in 17 cases in group A and 18 cases in group B. No difference was statistically significant.

Discussion-Conclusion: The used navigation system allowed a very precise implantation of a UKP for both conventional and minimal invasive navigated technique.

Purpose: Knowledge of the radiological axes in the normal lower limb is important for correction and reconstruction surgery. Classically, the femorotibial mechanical axis presents a zero angle on the anteroposterior view, with 3° femoral valgus being compensated by an equivalent tibial varus. Reference data have however been established with questionable methodology because they have been obtained with small selected samples.

Material and methods: We obtained teleradiograms of the lower limbs in 100 healthy volunteers free of any disease of the lower limbs and selected randomly among patients undergoing surgery for trauma or degenerative lesions of the upper limb. The following angles were measured by the same senior surgeon: mechanical femorotibial angle, orientation of the femoral condylar complex in relation to the mechanical axis of the femur, angle between the mechanial axis and the anatomic axis of the femur, orientation of the tibial plateaux in relation to the mechanical axis of the tibia.

Results: Sixty-nine men and 31 woman, mean age 39 years (range 17 – 62 years) participated in this study. The mean mechanical femorotibial angle was 179° (SD 3°, median 179°, range 168°–185°). The mean orientation of the femoral condylar complex in relation to the femoral mechanical axis was 91° (SD 2°, median 91°, range 86°–98°); 17 subjects had the classical value of 93°. The mean angle between the mechanical and anatomic axis of the femur was 6° (SD 1°, median 6°, range 3°–9°); 29 subjects had the classical value of 7°. The mean orientation of the tibial plateaux in relation to the mechanical axis of the tibia was 88° (SD 2°, median 88°, range 82°–84°); 14 subjects had the classical value of 87°.

Discussion and conclusion: The values considered to be normal in the literature only included 15–20% of the subjects in this study. Although there could be a theoretical selection bias in this series, it can be assumed that there is a wide dispersion of “normal” values around the means. The pertinence of this dispersion in clinical practice remains to be established. The question of individualising reconstruction or prosthetic procedures is raised.

Purpose: Treatment of infection in patients with an unstable bone is based on removal of implants, bone resection, reconstruction, and external fixation. We report a retrospective series of 11 patients who developed post-traumatic osteitis of the tibia on an unstable bone who were treated by removal of all implants, cleaning, antibiotics, and internal fixation using a centromedullary locked nail.

Material and methods: The series included seven men and four women, mean age 32.4 years (16–56). Initially, there were two closed fractures and nine open fractures (Gustilo II: 4, IIIA: 1; IIIB: 4) treated by external fixation in six cases, centromedullary locked nailing in four and plate fixation in one. Bacteriology results were available for all deep surgical samples. The initial implants were removed in all cases, followed by debridement sparing soft tissue, and reaming of the bone. Adapted antibiotics were prolonged for three months. Refixation using a centromedullary locked nail was performed at the first revision time in two cases and later after cleaning in nine (mean delay 28 days, range 2–53 days). Two cases required a flap for cover.

Results: There were two failures: one due to recurrent infection with a different germ, the other due to necrosis of a latissimus dorsi flap followed by amputation. There were nine successes with bone healing in all cases (first intention in eight and after complementary bone graft in one) and no recurrent infection at the current mean follow-up of 2.6 years.

Discussion: These eleven cases have a common feature of no extensive bone necrosis or major bone defect. Bone resection was basically related to reaming with a minimalistic approach for soft tissue debridement. Reliable bacteriological examinations, effective antibiotic therapy, and prolonged and rapid skin cover are essential elements for success.

Conclusion: This experience is limited but does demonstrate that locked centromedullary nailing can be successful for the treatment of long bone infections on unstable bones, considering that this could be the ideal fixation method.

Purpose: Centromedullary nailing with reaming is a recognised treatment for open leg fractures with a well-measured risk of postoperative infection. The development nailing procedures without reaming might reduce this risk.

Material and methods: We performed a Medline search using the following key words: nailing, tibia, open fracture, infection. To be retained for analysis, articles had to evaluate infectious risk of nailing with or without reaming, in clinical trials or experimental studies, with precise diagnostic criteria. Clinical articles retained were classed in three categories by decreasing value of their methodology: prospective randomised comparative studies, case-control studies, comparative observation studies, simple observation studies. Only comparative experimental and prospective comparative randomised studies were considered to be pertinent.

Results: Five articles met the predefined quality inclusion criteria and were retained for analysis: three experimental studies and two clinical trials. The experimental studies by Melcher (1995 and 1996) demonstrated a significant increase in infection rate and bacterial counts after nailing with reaming; there were two confounding factors however, steel or titanium nail and full or hollow nail which also had a significant effect on the rate of infection. The experimental work by Curtis (1995) did not find any difference in incidence and severity of infection between nailings with and without reaming. The two prospective comparative randomised clinical trials by Keating (1007) and Finkemeier (2000) included a total of 132 cases. the risk of infection was 8% after nailing with reaming and 7% after nailing without reaming (NS). The relative risk of infection after nailing with reaming was 1.02-fol greater than that without reaming (NS).

Discussion, conclusion: There is experimental evidence that would tend to prove that the risk of infection is lower after nailing with reaming, but it is insufficient to explain the mechanism of this lower rate. Inversely, although the clinical observation series tend to confirm these results, the two methodologically valid prospective comparative randomised studies did not find any difference. To date, there is no objective evidence ruling out the usefulness of nailing with reaming because of higher infection risk in open leg fractures.

Purpose: The biepicondylar axis of the femur is considered by many authors as a reliable reference axis for flexion-extension of the knee and to establish desirable orientation of the femoral component of a total knee arthroplasty. We studied the reproducibility of axis measurments made using an automatic digital acquisition system (OrthoPilot®, Aesculap, Chaumont, France). The system localises anatomic points in space from information obtained with a palpation probe carrying an infrared diode.

Material and methods: A consecutive series of 20 total knee arthroplasties (Search®, Aesculap, Chaumont, France) implanted by two senior surgeons on the same surgical team were studied. The mechanical axis of the femur was calculated prior to the study using kinematic acquisition of the position of the centres of rotation of the hip and the knee. The frontal reference plane was then defined from the most posterior point on the femoral condyles palpated with the probe as the plane containing the mechanical axis of the femur and parallel to the posterior bicondylar line. The apex of the two femoral epicondyles was obtained by direct palpation with the probe. A second plane passing through the apex of the epicondyles and parallel to the mechanical axis of the femur was thus defined. Three acquisitions were made for the same patient by each of the two surgeons without changing the posterior bicondylar reference plane. The angle between the frontal plane of reference and the biepicondylar plane was calculated directly by the software for each acquisition. The variability of the three measurements taken by each operator and between the two operators was studied with the Wilcoxon test for paired series and with Spearman’s coefficient of correlation.

Results: Mean intraobserver variability for the orientation of the biepicondylar axis was 4° for the two operators, with a maximum of 11° for the first operator and 9° for the second, the directions being random. The mean interobserver variability for this orientation was 4° with a maximum of 14°, again at random. All differences were statistically significant.

Discussion, conclusion: Measurements of the biepicondylar axis exhibit high intra- and interobserver variability, probably due to the anatomic conditions; the apex of the epicondyles is a blunt surface difficult to identify with precision. Use of this axis to determine the rotation of the femoral component of a total knee arthroplasty is thus an element of wide variability with measurement inaccuracy of a mean ± 5° but with a maximum that can reach 10°. The question remains to determine whether this uncertainty is tolerable or whether more precision is required.