Purpose. Failure resulting from a recurrent infection in total knee arthroplasty (TKA) is a challenging problem. Knee arthrodesis is one treatment option, however fusion is not always successful, as there is huge bone defect. The authors reports a new arthrodesis technique that uses a bundle of flexible intramedullary rods and an antibiotic-loaded cement spacer. Methods. There were 13 cases of arthrodesis due to recurrent periprosthetic joint infection, which were performed by the first author (WS Cho) at Asan Medical Center in Seoul from 2005 to 2014. All previous prosthetic components were removed and cement was thoroughly excised using a small osteotome. Two stage operation was done in most of cases. After thorough debridement, antibiotics loaded cement was inserted in first stage, flexible intramedullary rods were inserted retrogradely in the femoral side with the knee in flexion under fluoroscopy guidance. After filling the femoral intramedullary canal, the rods were then driven back securely into the tibial medullary canal. We aimed for as much rod length as possible to maximize stability. After 6 weeks of first stage operation, the rods of the femoral and tibial sides were arranged such that they overlapped and interdigitated to maximize mechanical strength, maintain the limb length and keep the rotational alignment. The interdigitating rod ends were tightly fixed using two (or three) cerclage wires. Antibiotic-loaded cement was filled into the knee joint space so that the cement is fit to the irregular contour of the femur and tibia, which was resulted from the severe bone loss. Postoperatively, patients were allowed to weight bear as tolerated. Results. The procedure was successful in every cases with no evidence of rod or cement failure at least 1 year follow up. Also there was no recurrence of infection. Conclusion. Although this simple method was not for bony union, the authors could achieve stable knee joint without recurrence of infection

Elongating rods have been used in the management of Osteogenesis Imperfecta (OI) for the last 50 years; complication rates have been high in many reviews of available techniques.

The functional outcomes and complications of a cohort of 22 Osteogenesis Imperfecta patients treated with 66 Sheffield Telescopic Intramedullary Rods at an average of 19 years post-initial surgery are analysed. The revision rate was 35% for any reason, 20% excluding revisions for rods separating due to growth. Re-operation other than revisions occurred in 10 rods (15%). Mobility was significantly better in the initial post-operative period (p=0.0015), this difference maintained in adulthood (p=0.0077). Back pain was the most frequent symptom. Symptoms related to the insertion technique across the knee and ankle were rare but those related to femoral trochanteric entry were common. Physeal damage following surgery was not experienced and all rods elongated.

All patients were satisfied with the outcome of their surgeries. SF-36 scores were significantly different for physical functioning domains, social functioning and vitality in comparison to normal population values, but comparable to other studies of OI.

The outcomes of this technique are satisfactory in adulthood; re-operation rates are high but related mainly to outgrowing the rods. Concerns regarding insertion with this fixed device at the knee and ankle are not founded, although proximal femoral fixation remains a problem.

Introduction and Purpose of Study. Osteogenesis imperfecta (OI) is a bone metabolic disorder that results in multiple fractures and deformities in children. The management of these patients should be in highly specialised units were multi-disciplinary management is mandatory. The aims of this study were twofold: 1. To determine the incidence and pattern of fractures in this population. 2. To determine the type, outcomes and complications of surgical treatment in the same population. Methods. A retrospective audit of patients treated for OI at a tertiary academic Hospital, from January 2002 to December 2011 was done. Results. Fifty three patients with OI were seen in the period under review. The patients came from six South African provinces including two other African countries. The male to female ratio was 1:1. The majority of patients were classified as type III and type IV, 19 (36%) and 14 (26%) respectively. Twelve patients (23%) had a first degree relative with OI. All patients received bisphosphonate therapy intravenously except two who were on oral medication. Seventeen patients (33%) had associated kyphoscoliosis – none were treated surgically. The most common long bone fractures were of the midshaft femur (61 fractures) and tibia (35 fractures). Seventeen patients (32%) received intramedullary rodding of either femur or tibia. Surgery had to be repeated due to rod migration in nine long bones (29%). The most common complication of surgery was rod migration and peri-implant fracture. Conclusion. Long bone fractures of the femur and tibia were most common cause of morbidity. Intramedullary rodding is a safe and effective means of long bone fracture management in patients with OI

Aim. To determine the preferable treatment for congenital pseudarthrosis of the tibia, we retrospectively reviewed 19 patients (20 limbs) treated consecutively over a 22 year period (1988–2007). Fifteen were followed up to maturity. The patients were assessed for union, leg length discrepancy (LLD), ankle valgus, range of ankle movement and distal tibial physeal injury. Results. The median age at surgery was 3 years. At surgery nineteen of the tibiae had a dysplastic constriction with a fracture (Crawford II-C or Boyd II) lesion. To obtain union in the 20 tibiae, 29 procedures were done. Nine failed primarily and required a second procedure to obtain union. Older patients (≥ 5 years) had a significantly higher success rate. Excision, intramedullary rodding and bone graft (IMR) was done in 14 tibiae: 10 (71.4%) were successful. Six of 10 primary operations and all 4 secondary operations after a previous failed procedure were successful. Ipsilateral vascularized fibula transfer (IVFT) was successful in 5 tibiae (3 primary and 2 secondary). Ilizarov with bone transport only, failed in two patients. Ilizarov with excision, intramedullary rodding and bone graft with lengthening was successful in 2 of 5 cases (40%); two sustained fractures at the proximal lengthening site. A median leg length discrepancy (LLD) of 3 cms occurred post surgery which was treated with contralateral epiphysiodesis. At maturity 3 patients had a LLD of ≥ 2cms. Six limbs had ankle valgus and were treated with stapling and tibio-fibular syndesmosis. Decreased range of movement of the ankle (< 50%) occurred in 7 patients. Distal tibial physeal injury occurred in 4 patients and was associated with repeated rodding. Conclusion. We concluded that surgery should be delayed as long as possible. If there is adequate tibial purchase for the rod distally, IMR is the best option. If purchase is inadequate, Ilizarov with rodding will avoid ankle stiffness. Epiphysiodesis is preferable to lengthening because of the risk of fracture above the rod. IVFT is a good option as a secondary procedure. NO DISCLOSURES

It is generally accepted that children treated for congenital pseudarthrosis of the tibia (CPT) should be followed-up until skeletal maturity, before drawing conclusions about the efficacy of treatment. We undertook this study in order to evaluate the long-term results of treatment of CPT by excision of the pseudarthrosis, intramedullary rodding and onlay cortical bone grafting. Among a total of 46 children with CPT treated by a single surgeon during a 20-year period, 38 had been treated by this technique and 11 of these children have reached skeletal maturity. These eleven cases (nine boys and two girls) formed the basis for this study. The mean age at presentation was 3.1 years (range 0.4–7 years); the mean age at index surgery was 3.2 years (range 0.7–7 years). The mean age at follow-up was 18.4 years (range 16–21.6 years) with a mean interval between surgery and final follow-up of 15.2 years (range 12.8–17.4 years). In all 11 children bone graft was harvested from the contralateral tibial diaphysis. Rods passed from the heel were used in nine children and in two Sheffield telescopic rods were passed from the ankle into the tibia. The fibula was divided in three children to ensure that the tibial fragments were in good contact before placing the graft astride them; the fibula was not touched in the remaining eight instances. To ensure that the intramedullary rod supported the pseudarthrosis site till skeletal maturity, revision rodding was performed as needed when the tip of the rod receded into the distal third. A thermoplastic clamshell orthosis was used till skeletal maturity. At final follow-up the union at the pseudarthrosis site was deemed to be ‘sound’ only if two independent observers concurred that there was definite bony continuity of the cortices on both the anteroposterior and lateral radiographs. Deformities of the tibia and ankle and ranges of motion of the knee, ankle and subtalar joints were noted. The limb lengths were measured with scanograms. The morbidity at the bone graft donor site was recorded. The function of the ankle was assessed by applying the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hind foot Score. Primary union of the tibial pseudarthrosis was achieved in nine of 11 cases with a mean time to union of 6.1 months. Secondary union was achieved in the remaining two cases following further intervention. At final follow-up sound union of the tibial pseudarthrosis was noted in all eleven patients but persistent pseudarthrosis of the fibula was present in 10 of 11 cases. The lateral malleolus was proximally situated in six cases. Ten of eleven children underwent a total of 21 secondary operations on an average of 2.6 years (range 0.5–5.1 years) after initial union was achieved. Six re-fractures were encountered in five patients at a mean of 6.1 years after index surgery. All the re-fractures united following the single episode of intervention. The overall mean shortening at final follow-up was 2.6 cm. At final follow-up, five patients had ankle valgus greater than 10 degrees. All the 11 patients walked without pain. Only two patients had significant motion at the ankle. Despite the ankle stiffness in the remaining children the AOFAS ankle-hindfoot scores ranged between 70 and 98 (mean 83.3). Our long-term results are comparable to the results of other studies in terms of the rate of union, the re-fracture rate, limb length discrepancy, residual deformity and the frequency of surgery

Objective. To explore whether good postoperative alignment could be obtained through simple individual valgus resection angle using common instruments in total knee arthroplasty with lateral bowing femur. Methods. Data of 46 TKAs with lateral bowing femur were collected prospectively, the center of the femoral intercondylar notch was the fixed drilling hole whether preoperative planning or intraoperative implementing. The intramedullary rod was put into the femur as deep as possible, until completely entrance or the distal point of the rod contact with the lateral cortical bone of the femur, which prevent the further entrance of the rod. Individual valgus resection angle ranging from 7°to 9°was performed according to preoperative planning, followed by meticulous assessment of matching between cutting surface and valgus resection angle. Postoperative hip-knee-ankle (HKA) angle?medial tibial plate angle and position of lower extremity alignment passing through the tibial plate were measured. Results. The preoperative measurement valgus resection angle include 14 cases of 8°, 13 cases of 9°, 5 cases of 10°, 2 case of 11°. The postoperative mean medial tibial plate angle was 89.5°±0.5°, mean HKA angle was 179.3°±0.8°. 27(79.4%), 23(67.6%) and 16 (47.1%) cases had restoration of mechanical axis to ±3°, ±2°and ±1°of neutral respectively, and there were 7 (15.2%) outlier (±3°). Excluding 3 cases of actual performed 9°valgus resection angle while preoperative measurement larger than 9°, both components were aligned within 3° of neutral in 88.2% of the knees. 27 (79.4%) cases had lower extremity alignment passing through the middle third of tibial plate, 7 (20.6%) cases pass through the medial third of the tibial plate. Conclusions. Excellent postoperative alignment could be obtained through simple individual valgus resection angle using common instruments in total knee arthroplasty with lateral bowing femur

Noting a decreasing number of transfemoral amputations following infection of Total Knee Arthroplasty (TKA) I studied a case of a patient which suffered an amputation following infection of TKA by MRSA. With assistance of all hospitals and the NHS it was able to classify all costs of this poor case. This study exposes a drama of a person which received a Total Knee Arthroplasty in the right knee at 66.0 years. 2 weeks after the implantation of TKA she presented a wound secretion, the microbiology shows: MRSA, Pseudomonas aeroguinos and Streptococcus. 4 surgical revisions followed without removing the TKA. 35 month later, with 68.9 years it was indispensable to remove the TKA in a 6th operation, implanting a spacer with Vancomycine. 1 month later removing of the spacer and implanting a second cemented TKA in the 7th surgery. With 70.2 years the removal of the second TKA was necessary because of infection with Pseudomonas aeroguinosa and Morganelli morganii. Now implantation of another spacer with Vancomycine. 1 month later with 70.3 years removal of the spacer molding an arthrodesis of the knee using an intramedullary femur to tibia rod. After that 4 revision surgeries with changing the intramedullary rod some wound revisions followed, ending in the 23rd operation with a transfemoral amputation with 71.1 years – 5 years after primary TKA. 3 month after transfemoral amputation the patient presented high temperature and a secretion of the scarf of the TT-stump; microbiology: MRSA. 2 more surgeries are necessary to stop the infection. This patient suffered over all 25 surgical procedures in 5.5 years. The hospitalization for acute infection of TKA led to 431 days in different hospitals in 33 months. Statement of charges from the hospitals € 74.046,92 in the last three years before amputation. Payments by the health insurance € 155.424,00 for all procedures. We will demonstrate the different costs of hospital procedures and distribution for the insurance for all performances

Aim. The aim of this study is to evaluate the effect of three-dimensional (3D) simulation with 3D planning software ZedKnee® (ZK) in total knee arthroplasty (TKA). Materials and methods. The participants in this study were all TKA patients whose operations were simulated by using ZK. The alignment of all components was evaluated with the ZK valuation software in postoperative computer tomography. Thirty patients (43 knees) met the inclusion criteria. 6 patients were male and 24 patients were female. The mean age of the 30 patients was 72 years old. Diagnoses for surgery were: osteoarthritis- 40 knees, rheumatoid arthritis- 2 knees and osteonecrosis- 1 knee. TKA was performed using the measured resection technique. The distal femur axis where the intramedullary rod would be inserted was drawn manually on the 3D image. Then, the angle between the distal femoral axis and the mechanical axis was measured. The rotational angles of the femoral components were determined from the automatically calculated angle between the posterior condylar axis and the surgical epicondylar axis (SEA) by using ZK. The ZK data used during the operation was the posterior condylar angle, the angle between the distal femoral axis and the mechanical axis and implant size. Results. The angle in coronal plane between the 3D mechanical axis and the distal femoral axis in preoperative planning ranged between 3 degrees and 11 degrees, mean 6.7 (SD 2.2) degrees. The postoperative femoral component alignment was on average 0.7 (SD 1.3) degrees in varus. Outlier of more than 3 degrees in coronal alignment was recognized in 3 cases (7%). The mean posterior condylar angle in preoperative planning was 3.8 (SD 1) degrees. The postoperative femoral component alignment was on average 1.5 (SD 1.6) degrees in external rotation to surgical epicondylar axis. Outlier of more than 3 degrees in rotational alignment was recognized in 6 cases (14%). The concordance rate between the preoperative planning size and the intraoperative selective size was 91%. Discussion. Some errors may be observed in the preoperative TKA X-ray planning, because of the rotational position of the femur while having the X-ray taken or angle of the X-ray beam. Kanekasu et al reported the measurement of the condylar twist angle during the X-ray and it was relatively correct compared with the measurement during CT. Max 1.9 degrees error occurred in the measurements using X-rays. It appeared that preoperative planning using CTs was more accurate than using X-rays. Conclusion. Femoral components with 3D simulation using ZK were fixed perpendicularly against the mechanical axis and parallel to the surgical epicondylar axis with high accuracy. We considered that the ZK 3D simulation in TKA is useful for the accurate alignment of femoral components

INTRODUCTION. To obtain appropriate joint gap and soft tissue balance, and to correct the lower limb alignment are important factor to achieve success of total knee arthroplasty (TKA). A variety of computer-assisted navigation systems have been developed to implant the component accurately during TKA. Although, the effects of the navigation system on the joint gap and soft tissue balance are unclear. The purpose of the present study was to investigate the influence of accelerometer-based portable navigation system on the intraoperative joint gap and soft tissue balance. METHODS. Between March 2014 and March 2015, 36 consecutive primary TKAs were performed using a mobile-bearing posterior stabilized (PS) TKA (Vanguard RP; Biomet) for varus osteoarthritis. Of the 36 knees, 26 knees using the accelerometer-based portable computer navigation system (KneeAlign2; OrthAlign) (N group), and 10 knees using conventional alignment guide (femur side; intramedullary rod, tibia side; extramedullary guide) (C group). The intraoperative joint gap and soft tissue balance were measured using tensor device throughout a full range of motion (0°, 30°, 45°, 60°, 90°, 120°and full flexion) at 120N of distraction force. The postoperative component coronal alignment was measured with standing anteroposterior hip-to-ankle radiographs. RESULTS. The mean joint gaps at each flexion angle were maintained constant in N group, and there was a tendency of the joint gap at midflexion ranges to increase in C group. The joint gaps at 30°and 45°of flexion angle in C group were significantly larger than that of in N group. The mean soft tissue balance at 0°of flexion was significantly varus in N group than that of in C group. Postoperatively, in N group, the mean femoral component alignment was valgus 0.1°± 1.3°(range, varus 2°- valgus 3°), the mean tibial component alignment was valgus 1.1°± 1.7°(range, varus 1°- valgus 3°) to the coronal mechanical axis. In C group, the mean femoral component alignment was varus 2.3°± 1.9°(range, varus 6°- valgus 1°), the mean tibial component alignment was valgus 2.0°± 1.3°(range, 0°- valgus 5°) to the coronal mechanical axis. There was statistically significant difference in femoral component alignment, there was no statistically significant difference in tibial component alignment. DISCUSSION AND CONCLUSION. The present study demonstrated that navigation-assisted TKA was prevented the joint gaps from increasing at 30°and 45°of flexion. However, it was difficult to achieve soft tissue balance at extension. In conventional TKA, the femoral component alignment was usually varus. In contrast, accelerometer-based portable navigation system is superior to implant the femoral component accurately. However, there were several cases that femoral component alignment is valgus because of a variation in the accuracy of this navigation system. Surgeons should be aware of difficulty to accomplish all of appropriate joint gap and soft tissue balance, and lower limb alignment in navigation-assisted TKA

Revision knee prostheses are often augmented with intramedullary stems to provide stability following bone loss. However, there are concerns with the use of such stems, including loosening caused by strain-shielding, end-of-stem pain, and removal of healthy bone surrounding the medullary canal. Extracortical fixation plates may present an alternative. The aim of the study was to quantitatively evaluate and compare strain-shielding in the tibia following implantation of a knee replacement component augmented with either a conventional intramedullary stem (design1), or extracortical plates (design2) on the medial and lateral surfaces. Eight composite synthetic tibiae were implanted with one of the two designs, painted with a speckle pattern, loaded in axial compression (peak 2.5 kN) using a materials test machine, and imaged with a 5-megapixel digital image correlation (DIC) system throughout loading. Bone loss was simulated in all models by removing a volume of metaphyseal bone. For four tibiae, the tibial tray was augmented with a cemented stem (∼150 mm). The others were augmented by extracortical plates (maximum 90 mm long) along the medial and lateral surfaces (Fig. 1). Strains were computed using an ARAMIS 5M software system between loaded and unloaded states in the longitudinal direction, for the medial, posterior and lateral surfaces of the tibiae. Strains were checked locally by use of strain gauge rosettes at three levels on medial, lateral and posterior aspects. The bone strains measured on the posterior surfaces were reported in three regions; proximal (0–70 mm, where the medial extracortical plate lies), middle (70–130 mm, the stem is present but not the extracortical plates), and distal (130–200 mm, beyond the stem). Mean longitudinal strains for both implant types were comparable in the distal region, and were greater than in the other regions (Fig 2). The mean strains differed considerably in the middle region: 565–715 μstrain with stemmed components 1050–1155 μstrain with plated components. Strains followed a similar pattern in the proximal region, particularly very close (20 mm) to the tibial tray component, where the stemmed component bones (775 ± 160 μstrain) displayed less surface strain than the plated component bones (1210 ± 180 μstrain). Strain-shielding was observed for both designs. The side plates were shorter than the intramedullary rods, so the region of the bone distal to the plates was not strain-shielded, while the same region was strain-shielded when a stemmed component was implanted. It was also shown that in the region of bone just distal of the tibial tray component, design1 shielded the bone from strain 56% more on average than design2. From these results, it can be speculated that the use of extracortical plate rather than intramedullary stems may lead to improved long-term results of revision TKA, assuming the plates and screws provide adequate stability. The extramedullary fixation system preserves more bone than IM fixation, and has the advantage of allowing use of primary TKA components, cemented over the subframe. Similar components have been developed for the femur

Background:. Varus or Valgus malpositioning of tibial prosthetic components in total knee replacement (TKR) surgery may lead to early failure due to increased polyethelene wear, soft tissue imbalancing, aseptic loosening and eventually revision surgery. Therefore, the clinical success of total knee arthroplasty (TKA) correlates with good component alignment. Conventional methods of coronal tibial alignment result in an acceptable range of prosthetic alignment in relation to the anatomical axis (tibial tangent angle). The measurement ranges from 90° ± 3°, but literature quotes that there is up to 27% of cases with coronal tibial alignment deviation of greater than 3°. Many studies show that the use of conventional intramedullary rod alignment versus extramedullary rod alignment gives similar results. The tibial alignment and overall prosthetic alignment in TKA has improved remarkably by using computerized navigation assisted surgery (CAS), with tibial tangent angle of 90° ± 3 in up to 97% of cases. However, the success of accurate tibial and femoral alignment depends on the surgeon and the data fed to the computer. Also long term results on survival rates of TKR using CAS is still pending. It is clear that assessing tibial alignment (ie. anatomical axis) with whatever method used faces challenges which will affect the tibial bony cuts and the final tibial tangent angle. To achieve a 90° tibial cut in relation to the anatomical axis we made use of fluoroscopy intra-operatively to assess the anatomical axis of the tibia and the correct alignment of the tibial cutting block. Methods:. TKR's were performed on 36 consecutive patients over a 4 month period. The aim was to assess the coronal tibial alignment of the tibial component intra-operatively using fuloroscopy. A conventional manual extramedullary alignment rod with its tibial cutting block was used and the final positioning was confirmed with an image intensifier. The tibial cutting block must be at 90° to the anatomical axis of the tibia. The rest of the TKR procedures were performed as routinely described. Post-operative radiographs were taken on the same day as the surgery and again at six week follow up visit when the tibial tangent angle was measured. Results:. The coronal tibial angulation was consistent at 0° in 32 knees with a 1°–2° deviation in 4 knees. Conclusion:. We conclude that the use of fluoroscopy intra-operatively can improve the tibial component alignment and thus decrease the cumulative errors which have significant and dramatic effects on the function and the longevity of the total knee prosthesis

We prospectively studied 25 cases of chom (15 femora and 10 tibia). There were 24 males and one female, with the mean age being 33 years (range, 21–58 years). All patients had radiological evidence of chronic osteomyelitis with osteolysis, cortical thinning, sequestration, involucrum, and both medullary and soft tissue swelling. All patients had culture-documented chronic osteomyelitis. The clinical records, radiographs, bone repair, sedimentation rate, and functional outcome using the Enneking/Musculoskeletal Tumor Society System were evaluated.5 ACIIN was used in all cases after adequate debridement. Patients were classified according to the amount of bone defect present after debridement. Infection control was judged on the basis of discharge through the wound and laboratory parameters. All patients were followed-up, with an average follow-up time of 32 months (range, 18–40 months). The mean duration of retention of the intramedullary rod was 8 weeks (range, 6–12 weeks). The mean preoperative sedimentation rate was 43 mm (range 22 to 105). The local antibiotic used was gentamycin (18 patients) and gentamycin plus vancomycin (7 patient). The mean follow-up was 32 months (range 18 to 40). The mean sedimentation rate at most recent followup was 10 mm. The defect size at most recent followup was 2.1cc, thus making the bone repair 89%. The mean functional score at follow-up was 27 out of 30 points. The one patient with a mixed infection ended up with a functional score of 20. This patient scored 3 points for pain, 3 points for function, 2 points for emotional acceptance and 2 points for gait. There were no fractures, infection relapses, or additional surgery to date. ACIINs are useful for infection control in cases of chom of long bones

Introduction. A longer operative time will lead to the development of any postoperative complications in total knee arthroplasty (TKA). According to previous reports, a significant increase in TKA procedure time done by novice surgeons was observed compared to high-volume surgeons. Our purpose was to investigate and to clarify the important maneuver necessary for novice surgeons to minimize a surgical time in TKA. Methods. A total of 300 knees in 248 patients, averaged 74.6 ± 8.7 years, were enrolled. All primary TKAs were done using same instruments (Balanced Knee System®, PS design, Ortho Development, Draper, UT) and same measured resection technique at 14 facilities by 25 orthopedic surgeons. Surgeons were divided into three surgeon groups (4 experts, 9 medium volume surgeons, 12 novices). All methods were approved by our institution's ethics committee. We divided the operative technique into 5 steps to make comparisons of step-by-step surgical time among surgeon groups of different levels. We defined Phase 1 as performing surgical exposure from skin incision to insertion of the intramedullary rod into the femur. Thereafter, the distal and AP surface of the femur, proximal tibia, the chamfer and PS box of the femur, and patella were resected in Phase 2. In Phase 3, a setup the trial component and a keel of the tibia were done after a confirmation of appropriate ligament balance using the spacer block. Then, a bone surface was irrigated with 2000ml of saline after the removal of the trial component. Subsequently, permanent components were fixed with use of bone cement in Phase 4. Finally, the final irrigation using 2000ml saline and wound closure were done in Phase 5. Every phase of the surgical time was recorded in each TKA. As a statistical analysis, operation data including length of skin incision, component size, operation time in each phase, and ratio of surgical time in each phase to whole surgical time, were compared using non-repeated measures of ANOVA and a post hoc Bonferroni correction. The threshold for statistical significance was set at a p value of less than 0.05. Results. A total of 62 TKAs were done by novice surgeons. On the other hand, medium volume surgeons and experts performed 119 and 119 TKAs, respectively. Gradually, differences among three groups became large phase by phase. Significant differences were detected among groups in each phase (Fig.1). Novice surgeons and medium volume surgeons took much time even in a basic technique including the exposure and wound closure (Fig.2). Regarding the ratio, no significant differences were detected among groups in Phase 2, 3, and 5. Experts and medium volume surgeons seemed to take caution in fixation of the permanent component. Interestingly, the ratio was still notably different among groups in Phase 1 (Fig.3). Conclusions. Significant differences among groups were seen in bone resection and implant fixation as well as in a basic technique including exposure and wound closure. Ratio was also notably different among groups in surgical exposure. Therefore, a basic technique would be important to reduce surgical time in novice surgeons in primary TKA

Introduction. The efficacy and accuracy of computer navigation systems in total knee arthroplasty (TKA) have been proven in recent years. However, potential disadvantages associated with navigation systems, such as increased surgical time and registration errors, have been reported. Currently, we use a navigation system only for the femoral side. We use the conventional extramedullary guide system for the tibial side (hybrid navigation method) because we have increased the accuracy of tibial positioning in the coronal plane with the conventional system by considering the following key points. (1) Set the extramedullary alignment guide to avoid the rotational mismatch between the proximal part of the tibia and the ankle joint. (2) Insert the tibial component along the AP axis of the resected surface. (3) Remove the protruding bone at the antero-lateral edge of the tibia to obtain the flat, resected surface of the tibia. The purpose of this study was to determine the accuracy of the hybrid navigation method. Methods. We compared the postoperative alignment of 60 TKAs implanted using the conventional alignment guide system with 30 TKAs implanted using the hybrid image-free navigation method. The average age was 74.2 (range, 50 to 85) years in the conventional group and 73.6 (range, 51 to 84) years in the hybrid group. The intramedullary alignment guide was used for the femur in the conventional group. The knees were evaluated using full-length, weight-bearing anteroposterior radiographs. Results. For the conventional group, the mean coronal tibial component angle was 89.9 ± 1.09 degrees (range, 88.0 to 92.0 degrees) (Fig. 1b). The ideal angle within 3 degrees for the tibial component was obtained in 100% of the cases. The mean posterior inclination angle was 83.7 degrees. The mean coronal femoral angle was 90.5 ± 2.06 degrees (range, 84.0 to 96.0 degrees) (Fig. 1a). The ideal angle within 3 degrees for the femoral component was obtained in 85.0% of the cases. For the hybrid navigation group, the mean coronal tibial component angle was 89.6 ± 0.73 degrees (range, 88.0 to 91.0 degrees) (Fig. 2b). The ideal angle within 3 degrees for the tibial component was obtained in 100% of the cases. The mean coronal femoral component angle was 89.4 degrees (range, 86.0 to 92.0 degrees) (Fig. 2a). The ideal coronal angle within 3 degrees for the femoral component was obtained in 96.7% of the cases. Discussion and Conclusion. Our results demonstrated the accuracy of coronal tibial component positioning with the conventional extramedullary alignment guide system by considering the key points described above. However, the accuracy of femoral component positioning with the conventional intramedullary rod is limited. Therefore, the hybrid navigation method could be an alternative to reduce surgical time while maintaining the accuracy of the tibial component positioning. In conclusion, we recommend the hybrid navigation method in total knee arthroplasty

Purpose. Arthritis is the most common chronic illness in the United States. TKR provides reliable pain relief and improved function for patients with advanced knee arthritis. Total joint replacement now represents the greatest expense in the national healthcare budget. Surgical costs are driven by two key components: fixed and variable costs. Patient Specific Instruments™ (PSI, Zimmer, Warsaw, IN, USA) has the potential to reduce both fixed and variable costs by shortening operative time and reducing surgical instrumentation. However, PSI requires the added costs of pre-operative MRI scanning and fabrication of custom pin guides. Previous studies have shown reduction in operating room times and required instrumentation, but question the cost-effectiveness of the technology. Also, these studies failed to show improvement in coronal alignment, but call for additional studies to determine any improvement in clinical function and patient satisfaction. Our pilot study aims to compare the incremental PSI costs to fixed and variable OR cost savings, and compare meaningful patient and clinical outcomes between PSI and standard TKR surgeries. Methods. This IRB approved, prospective, randomized pilot trial involves 20 TKR patients. Inclusion criteria includes: diagnosis of osteoarthritis, ability to undergo MRI, and consent for primary TKR. Following informed consent, patients are randomized to PSI or standard TKR. Patients randomized to PSI undergo pre-operative non-contrast MRI of the affected knee at least 4 weeks prior to surgery. Custom pin guides are prototyped from 3D pre-operative planning software customizable to individual surgeon and patient. All surgeries will be completed by a single surgeon (DA), using a medial parapatellar arthrotomy and Zimmer Nexgen™ implants. Surgical technique for PSI patients utilizes custom pin guides to determine placement of the femoral and tibial cutting guides, whereas an intramedullary femoral rod and extramedullary tibial guide are used in standard TKR patients. Our pilot study will compare numerous intra-operative and post-operative variables between the two patient cohorts. Intra-operative variables include: bony cutting time, tourniquet time, total OR time, surgical instrumentation, and bony resection height. Post-operative variables include: instrument processing and sterilization, blood transfusion, pain medication usage, length of stay, complications (including hospital readmission), and patient reported outcomes (SF-36, WOMAC, and satisfaction) at 4 weeks, 6 months, and 1 year. Additional economic sensitivity analyses using hospital and national cost-to-charge figures will quantify the potential added revenue or costs of implementing the PSI system. Discussion. This pilot study will illustrate the potential benefits of the PSI technology. To our knowledge no clinical trials have been published on the PSI system. Former studies have neglected to include meaningful clinical and patient outcomes, which could potentially add to the cost savings of the technology through reduced blood transfusions, length of stay, and hospital readmission. Additionally, improved rotational alignment may produce superior patient function and satisfaction. Studies recently published on alternative patient-specific TKR systems question the cost-effectiveness and technical improvement of patient-specific instrumentation. Although our sample size may fail to produce statistical significance, the consummate measurement of all the proposed hospital, surgical, and patient factors will inform future randomized multicenter trials