Introduction. Stryker
Total hip arthroplasty (THA) is an effective treatment for symptomatic hip osteoarthritis (OA). While computer-navigation technologies in total knee arthroplasty show survivorship advantages and are widely used, comparable applications within THA show far lower utilisation. Using national registry data, this study compared patient reported outcome measures (PROMs) in patients who underwent THA with and without
A cadaver study using six pairs of lower limbs was conducted to investigate the accuracy of
Introduction. Two aspects are very important for knee joint replacement – restoration of biomechanical limb axis and achieving ligaments balance.
Individuals learn to master new motor skills (such as learning a new surgical technique) by evaluating available feedback to alter future performance. Continuous concurrent augmented feedback is supplementary information presented to the learner throughout the performance of a task. An example of this type of feedback is the visual information provided by
Alignment of the femoral component during hip resurfacing has been implicated in the early failure of this device. Techniques to facilitate a more accurate placement of the femoral component may help prevent these early failures. We aim to establish whether the use of imageless
Purpose. This meta-analysis was designed to evaluate the effects of
Introduction. Restoration of normal hip biomechanics is vital for success of total hip arthroplasty (THA). This requires accurate placement of implants and restoration of limb length and offset. The purpose of this study was to assess the precision and accuracy of
Purpose. Patient-matched instrumentation is advocated as the latest development in arthroplasty surgery. Custom-made cutting blocks created from preoperative MRI scans have been proposed to achieve perfect alignment of the lower limb in total knee arthroplasty (TKA). The aim of this study was to determine the efficacy of patient-specific cutting blocks by comparing them to navigation, the current gold standard. Methods. 60 TKA patients were recruited to undergo their surgery guided by Smith & Nephew Visionaire Patient-Matched cutting blocks. Continuous
Patient-matched instrumentation is advocated as the latest development in arthroplasty surgery. Custom-made cutting blocks created from preoperative MRI scans have been proposed to achieve perfect alignment of the lower limb in total knee arthroplasty (TKA). The aim of this study was to determine the efficacy of patient-specific cutting blocks by comparing them to navigation, the current gold standard. 25 TKA patients were recruited to undergo their surgery guided by Smith & Nephew Visionaire Patient-Matched cutting blocks. Continuous
Arthrodesis is used most commonly as a salvage procedure for failed total knee arthroplasty (TKA). For successful arthrodesis, a stable fusion technique and acceptable limb mechanical alignment are needed. Although the use of intramedullary alignment rods might be helpful in terms of achieving an acceptable limb mechanical axis, fat embolism and intramedullary dissemination of an infection or reactivation of latent infection might occur in failed TKA cases. However, computer-assisted surgery allows precise cuts to be made without breaching medullary cavities. Here, the authors describe a case of knee arthrodesis performed by
Introduction:. Restoration of normal hip biomechanics is vital for success of total hip arthroplasty (THA). This requires accurate placement of implants and restoration of limb length and offset. The purpose of this study was to assess the accuracy of
Hip Resurfacing is now an established treatment option for young active patients with osteoarthritis. However, there is slow uptake of hip resurfacing by some surgeons, with concern regarding failure from femoral neck fracture, a small but significant risk. Femoral neck fracture may follow notching of the neck, which occurs upon preparing the femoral head after inserting the femoral head/neck guide-wire. The placement of the femoral head/neck guide-wire is a concern for even experienced surgeons routinely, and in difficult cases of femoral head/neck deformity this is especially so. For the first time a preliminary series of Durom hip resurfacings, based on the successful Metasul bearing, were implanted using a computer image guidance system. The aim of
Total hip arthroplasty (THA) is an effective treatment for symptomatic hip osteoarthritis (OA). Computer-navigation technologies in total knee arthroplasty show evidence-supported survivorship advantages and are used widely. The aim of this study was to determine the revision outcome of hip commercially available navigation technologies. Data from the Australian Orthopaedic Association National Joint Replacement Registry from January 2016 to December 2020 included all primary THA procedures performed for osteoarthritis (OA). Procedures using the Intellijoint HIP® navigation were identified and compared to procedures inserted using ‘other’
Background: The rates of primary and revision knee arthroplasty in the United States have been increasing. Simultaneously, several studies have reported increased complication rates when these procedures are performed at low-volume centers. One innovation designed to improve knee arthroplasty outcomes is
Background. The literature quotes up to 20% dissatisfaction rates for total knee replacements (TKR). Swedish registry and national joint registry of England and Wales confirm this with high volumes of patients included. This dissatisfaction rate is used as a basis for improving/changing/modernising knee implant designs by major companies across the world. Aim. We aimed to compare post TKR satisfaction rates for navigated and non navigated knees. Methods. This was a retrospective analysis of prospectively collected data. All patients undergo comprehensive preoperative evaluation and comprehensive consent process and same rehabilitation protocols are followed as standard practice. Two groups were established depending on whether surgery was performed with or without
The Gpsystem Medacta vision system is composed of an infrared camera that produces and receives infrared rays reflected by almost 3 reflectors mounted on different rigid body devices (F=femoral, T=tibial, G=guide), in order to determine its position with an error lower than 0.35mm. Data received from this vision system are than elaborated by the Cinetique Gpsystem Version 1.0 system in order to determine the correct cutting guide positioning both for the femur and the tibia. The cutting guide is moved on different planes by 5 electric engines applied on 5 no ending screws. The first step of this system is determining, with the F and the T rigid bodies, patient’s lower limb kinematic in order to evaluate its mechanical axis, its flexion-extension range of movement and its pathological deviations. The second step is evaluating anatomical landmarks to find out the correct degrees of tibial and femoral cuts: these landmarks are the medial and lateral tibial glena, the distal femoral condyles, the posterior femoral condyles, the anterior femoral cortex, the tibial tuberosity, the Whiteside line and the epycondilar axis (each anatomical landmark is identified by multiple points in order to decrease possible errors). The third step is applying the cutting guide and the Grigid body on the femoral clamp in order to estimate the correct level for the tibial cut than, once the tibial osteotomy is done the vision system controls its correct execution and the soft tissue balancing of the knee. The fourth step is calculating with the Gpsystem the correct orientation of the femoral cutting guide and checking its positioning and cutting execution. The last step is applying the test-prosthesis verifying the mechanical axis of the knee and than assembling the definitive prosthesis. Since now we have applied 10 Cinetique knee prosthesis with the Medacta
Accurate implant alignment, prolonged operative times, array pin site infection and intra-operative fracture risk with computer assisted knee arthroplasty is well documented. This study compares the accuracy and cost-effectiveness of the pre- operative MRI based Signature custom made guides (Biomet) to intra-operative
Purpose:. The use of
The presence of retained metalwork, previou fractures or osteotomies makes TKA surgery challenging. Obstructed intramedually canals can produce difficulty with the use of IM instrumentation whilst the altered alignment can result in problematic soft tissue balancing. We present a series of 35 patients with deformity who underwent a successful TKA. Between July 2003 and January 2006 35 patients were operated on between 3 centres. All had extraarticular deformities in either the femur or tibia due to previous fractures or exposure to surgery. All underwent TKA surgery using an image free
Introduction: The long-term results of total hip replacement can be improved by accurate placement of the implants, leading to restoration of hip biomechanics and prevention impingement from of implant malposition. Pelvic obliquity from patient positioning during surgery prevents accurate intra-operative assessment of component placement.
Introduction. Computer-assisted hip navigation offers the potential for more accurate placement of hip components, which is important in avoiding dislocation, impingement, and edge-loading. The purpose of this study was to determine if the use of computer-assisted hip navigation reduced the rate of dislocation in patients undergoing revision THA. Methods and Materials. We retrospectively reviewed 72 patients who underwent computer-navigated revision THA [Fig. 1] between January 2015 and December 2016. Demographic variables, indication for revision, type of procedure, and postoperative complications were collected for all patients. Clinical follow-up was performed at 3 months, 1 year, and 2 years. Dislocations were defined as any episode that required closed or open reduction or a revision arthroplasty. Data are presented as percentages and was analyzed using appropriate comparative statistical tests (z-tests and independent samples t- tests). Results. All 72 patients (48% female; 52% male) were included in the final analysis [Fig. 2]. Mean age of patients undergoing revision THA was 70.4 ± 11.2 years. Mean BMI was 26.4 ± 5.2 kg/m. 2. The most common indications for revision THA were instability (31%), aseptic loosening (29%), osteolysis/eccentric wear (18%), infection (11%), and miscellaneous (11%). During revision procedure, polyethylene component was most commonly changed (46%), followed by femoral head (39%), and acetabular component (15%). At 3 months, 1 year, and final follow-up, there were no dislocations among all study patients (0%). Compared to preoperative dislocation values, there was a significant reduction in the rate of dislocation with the use of computer-assisted hip navigation (31% vs. 0%; p<0.05). Discussion. Our study demonstrates a significant reduction in the rate of dislocation following revision THA with the use of
Aim: Accurate soft tissue balance in total knee arthroplasty (TKA) is not only technically challenging but also difficult to teach to trainees; we believe that
Introduction: While
The use of a navigation system in musculoskeletal tumour surgery enables the integration of pre-operative CT and MRI images to generate a precise three-dimensional anatomical model of the site and the extent of the tumour. We carried out six consecutive resections of musculoskeletal tumour in five patients using an existing commercial
Background. Bone preservation is desired for future revision in any knee arthroplasty. There is no study comparing the difference in the amount of bone resection when soft tissue balance is performed with or without
Correct component positioning in hip resurfacing is a key determinant for a successful outcome. The aim of the study was to compare the radiographic and perioperative clinical parameters between navigated and non-navigated resurfacing groups and to look at the effect of navigation on the learning curve. Pre and post operative radiographs were analyzed with respect to neck-shaft angle, implant-shaft angle, notching, lateral position, and cup inclination. The target implant position was to place the femoral component in relative valgus to the neck-shaft angle using the smallest component without notching the femoral neck. The target cup position was 40–45 degrees inclination. Statistical analysis was performed comparing the two groups with respect to implant position, complications and differences between experienced verses inexperienced surgeons. Data was recorded for 51 patients (24 navigated, 27 conventional). There was no significant difference in implant-shaft angle or presence of notching between the two groups. There were two cases of notching in the non-navigated cohort. Lateral positioning (central placement stem, centering component on shaft) was significantly more accurate for the navigated cases (P<
0. 001). There was no significant difference in cup inclination between the two groups. In the non-navigated group three patients were converted to a total hip replacement (one fracture, one impingement pain, one intra-operative notching) and there was 1 case of medial wall fracture of the acetabulum. There was a 14.8% complication rate for the non-navigated group with no complications in the navigated group. Complications experienced 2.6% vs. training 17.4%. Training navigated 0% vs Training non-navigated 30%; Experienced nav 0% vs. experienced non-navigated 5.5%. Positioning of the femoral component in the lateral plane and A-P head-neck ratios is significantly more accurate with the use of
Aim: The study was conducted to evaluate differences between simultaneous and sequential cementing of the tibial and femoral components in total knee joint replacement in relation to final component alignment. Our hypothesis was that cementing the components sequentially increases accuracy of the final position. Method: This was a prospective and randomised study, performed using a
Aims. Due to the complex anatomy of the pelvis, limb-sparing resections
of pelvic tumours achieving adequate surgical margins, can often
be difficult. The advent of
Purpose: The purpose of this study was to evaluate the accuracy and precision of 3 common methods used to produce posterior tibial slope during total knee arthroplasty. Method: The study population consisted of 110 total knee arthroplasties in 102 patients that underwent total knee arthroplasty. All procedures were performed using a standard medial parapatellar approach and all knees were replaced using the Scorpio Knee System (Stryker, Mahwah, NJ) of implants and instruments. Three treatment groups were identified retrospectively based on the method used to produce the posterior tibial slope. Group 1 used an extramedullary guide with a 0 degree cutting block tilted by placing 2 fingers between the tibia and the extramedullary guide proximally and three fingers between the tibia and guide distally to produce a 3 degree posterior slope (N=40). Group 2 used
The purpose of this study was to evaluate 3 methods used to produce posterior tibial slope. Methods. 110 total knee arthroplasties performed during a 4 year period were included(2005 to 2009). All operations were performed by 2 surgeons. Group 1 used an extramedullary guide with a 0 degree cutting block tilted by placing 2 fingers between the tibia and the extramedullary guide proximally and three fingers distally to produce a 3 degree posterior slope (N=40). Group 2 used
Computer navigated total knee arthroplasty (TKA) has several proposed benefits including reduced post operative blood loss. We compared the total blood volume loss in a cohort of morbidly obese (BMI>
40) patients undergoing computer navigated (n=30) or standard intramedullary techniques (n=30) with a cohort of matched patients with a BMI<
30 also undergoing navigated (n=31) or standard TKA (n=31). Total body blood loss was calculated from body weight, height and haemotocrit change, using a model which accurately assesses true blood loss as was maximum allowable blood loss. The groups were matched for age, gender, diagnosis and operative technique. The mean true blood volume loss was significantly (p<
0.001) less in the computer assisted group (1014±312mls) compared to the conventional group (1287±330mls). Patients with a BMI >
40 and a computer navigated procedure (1105 ±321mls) had a significantly lower (p<
0.001) blood volume loss compared to those who underwent a conventional TKA (1399±330mls). There was no significant difference in the transfusion rate or those reaching the maximum allowable blood loss between groups. This study confirms a significant reduction in total body blood loss between computer assisted and conventional TKA in morbidly obese patients. However
Posterior slope of the tibial component is an important factor in overall alignment of Total Knee Arthroplasty. The purpose of this study was to compare the accuracy and reproducibility of tibial bone cuts utilizing traditional extramedullary 0 degree and angled 5 degree cutting blocks, and
Introduction: This study aimed to determine the accuracy of
Extensive release of postero-lateral structures may be required to correct rigid and severe valgus deformities during total knee arthroplasty. Current techniques are technically difficult, may not accurately restore soft tissue balance, and are associated with postoperative complications. We evaluated the results of using
Total knee arthroplasty (TKA) is one of the commonest orthopaedic procedures. Traditionally the surgeon, based on experience, releases the medial structures in knees with varus deformity and lateral structures in knees with valgus deformity until subjectively they feel that they have achieved the intended alignment. The aim of this prospective study was to record the frequency of medial and lateral releases for computer navigated TKAs. Seven four consecutive patients operated on by a single surgeon were included in this study. All patients had TKA using either Stryker or Orthopilot
Introduction/Aims: Early results of a prospective randomised control trial suggested improved position of components implanted during primary hip replacement. The aim of this study is to definitively show the benefit of
The aim of our study was to compare the precision and effectiveness of a CT-free
Implant alignment in knee arthroplasty has been identified as critical factor for a successful outcome. Human error during the registration process for imageless
Introduction. It is widely accepted that
Purpose: The aim of our study was to compare the precision and effectiveness of a CT-free
Introduction. Surgical techniques for implant alignment in total knee arthroplasty (TKA) is a expanding field as manufacturers introduce patient-specific cutting blocks derived from 3D reconstructions of pre-operative imaging, commonly MRI or CT. The patient-specific OtisMed system uses a detailed MRI scan of the knee for 3D reconstruction to estimate the kinematic axis, dictating the cutting planes in the custom-fit cutting blocks machined for each patient. The resulting planned alignment can vary greatly from a neutral mechanical axis. The purpose of this study was to evaluate the early fixation of components in subjects randomized to receive shape match derived kinematic alignment or conventional alignment using
Introduction We present our earliest series of computer assisted minimally invasive fixation of intertrochanteric hip fractures using the dynamic hip screw. Methods The first five cases of computer assisted minimally invasive dynamic hip screw fixation of intertro-chanteric femur fracture are presented. We used the Medivision
We report our five-year functional results comparing navigated and conventional total knee replacement. To our knowlege this represents the first Level 1 study comparing function in navigated and conventional total knee replacement at five years. An origianl cohort of 71 patients undergoing Duracon (Stryker Orthopaedics, St. Leonards, Australia) total knee replacement without patellar resurfacing were prospectively randomised to undergo operation using
Purpose.
Introduction. Blood loss after TKA varied, but not uncommon with up to 1500 ml or a decrease in hemoglobin of 3–4 g/dL. In addition to improving prosthetic alignment, computer-assisted TKAs also contribute to reduced operative blood loss and systemic emboli. These observations imply that navigation TKAs may cause less microvascular endothelial damage than conventional TKAs. Cell adhesion molecules (CAMs) have been employed as markers for endothelial or vascular damage. We hypothesized serum levels of CAMs in patients receiving navigation TKAs may be different from those receiving conventional TKAs. Material and Methods. A prospective comparative study, enrolling 87 patients with osteoarthritic knees was conducted. There were 54 navigation TKAs and 33 conventional TKAs. Levels of cell adhesion molecules (CAM) in sera and hemovac drainage were measured by ELISA before and 24 hours after the surgery. Hb and Ht were checked pre- and post-operatively. The blood loss was calculated though the formula by Nadler and Sehat et al. Results. There were no significant differences in gender, affected side, age or BMI between the two group. The calculated volume of blood loss in the
We previously compared component alignment in total knee replacement using a computer-navigated technique with a conventional jig based method. Improved alignment was seen in the computer-navigated group (Beaver et al. JBJS 2004 (86B); 3: 372–7.). We also reported two-year results showing no difference in clinical outcome between the two groups (Beaver et al. JBJS 2007 (89B); 4: 477–80). We now report our five-year functional results comparing navigated and conventional total knee replacement. To our knowlege this represents the first Level 1 study comparing function in navigated and conventional total knee replacement at five years. An original cohort of 71 patients undergoing Duracon (Stryker Orthopaedics, St. Leonards, Australia) total knee replacement without patellar resurfacing were prospectively randomised to undergo operation using
Purpose. The purpose of this study was to analyze rotational kinematic patterns in knees treated with either cruciate-retaining (CR) or posterior-stabilized (PS) total knee arthroplasty (TKA), using an intra-operative navigation technique, and to clarify the factors that affect of the rotational kinematics and the difference rotational kinematics patterns between CR- and PS- TKA. Methods. A total of 35 knees (35 patients) were included in this study, deformed valgus, sever flexion contractures, and highly unstable knees were excluded. These knees were allocated to CR (NexGen CR-Flex) or PS (NexGen PS-Flex) implants and underwent TKA with a
Introduction. Computer assisted surgery (CAS) systems have been shown to improve alignment accuracy in total knee arthroplasty (TKA), yet concerns regarding increased costs, operative times, pin sites, and the learning curve associated with CAS techniques have limited its widespread acceptance. The purpose of this study was to compare the alignment accuracy of an accelerometer-based, portable navigation device (KneeAlignÒ 2) to a large console, imageless CAS system (AchieveCAS). Our hypothesis is that no significant difference in alignment accuracy will be appreciated between the portable, accelerometer-based system, and the large-console, imageless navigation system. Methods. 62 consecutive patients, and a total of 80 knees, received a posterior cruciate substituting TKA using the Achieve CAS
Introduction: We previously compared component alignment in total knee replacement using a computer-navigated technique with a conventional jig based method. Improved alignment was seen in the computer-navigated group (Beaver et al. JBJS 2004 (86B); 3: 372–7.). We also reported two-year results showing no difference in clinical outcome between the two groups (Beaver et al. JBJS 2007 (89B); 4: 477–80). We now report our five-year functional results comparing navigated and conventional total knee replacement. To our knowlege this represents the first Level 1 study comparing function in navigated and conventional total knee replacement at five years. Methods: An original cohort of 71 patients undergoing Duracon (Stryker Orthopaedics, St. Leonards, Australia) total knee replacement without patellar resurfacing were prospectively randomised to undergo operation using
Recent studies suggest the use of
Arthritic knees, for the purpose of surgical correction during arthroplasty, are generally thought to be either varus knees or valgus knees and soft tissue releases are done in accordance with the same concept. This view is dependent on the clinical deformity in extended knee and the plain AP radiograph of the extended knee. This concept is now challenged by the observations from our study of the arthritic knee kinematics using
Aims: Malposition of the acetabular cup after THR leads to dislocations and impingement, reduces ROM and increases pressure and wear inside the cup. The use of the OrthoPilot? kinematic
We designed this study to determine the clinical evidence to support use of the five degree tibial extra-medullary cutting block over the zero degree cutting block. We identified three groups of patients from the databases and clinical notes at St Michaels Hospital, Toronto. Group one were primary total knees performed using the five degree cutting block, group two were primary total knees performed using the zero degree cutting block and the third group were computer navigated primary total knees. Patients in all three groups were age and sex matched. The senior author advocating use of the five degree block aimed to obtain a five degree posterior slope. The senior author who advocated the use of
Introduction. Leg length and offset are important considerations in total hip arthroplasty (THA). Navigation systems are capable of providing intra-operative measurements, which help guide the surgeon in leg length and offset adjustment. Objective. This controlled study investigates whether the use of
Our aim was to assess the intra- and inter-observer reliability in the establishment of the anterior pelvic plane used in imageless computer-assisted navigation. From this we determined the subsequent effects on version and inclination of the acetabular component. A cadaver model was developed with a specifically-designed rod which held the component tracker at a fixed orientation to the pelvis, leaving the anterior pelvic plane as the only variable. Eight surgeons determined the anterior pelvic plane by palpating and registering the bony landmarks as reference points. The exact anterior pelvic plane was then established by using anatomically-placed bone screws as reference points. The difference between the surgeons was found to be highly significant (p <
0.001). The variation was significantly larger for anteversion (
Background: Leg length equality and femoral offset restoration are important parameters related to success of total hip arthroplasty (THA). However, it is not uncommon for errors to occur during surgery which can lead to less optimal functional result and potential source for litigation. Several techniques that are commonly used to assess leg length and femoral offset during THA include pre-operative templating, intra-operative measurements with a ruler using bony landmarks, assessing soft tissue tension and using measurement device with a reference pin in the iliac crest. We have previously reported on our precision to reconstruct the diseased hip with THA done without navigation. Post-operative radiographic analysis demonstrated that leg length was restored to within +/− 4mm of the contralateral side in only 60% of the patients with 4 patients needing a shoe lift. With regards to femoral offset reconstruction, it was increased by a mean of 5.1 mm and restored to within +/− 4mm of the normal contralateral side in only 25% of patients.
We previously compared the component alignment in total knee replacement using a computer-navigated technique with a conventional jig-based method. We randomly allocated 71 patients to undergo either computer-navigated or conventional replacement. An improved alignment was seen in the computer-navigated group. The patients were then followed up post-operatively for two years, using the Knee Society score, the Short Form-36 health survey, the Western Ontario and McMaster Universities osteoarthritis index, the Bartlett Patellar pain questionnaire and the Oxford knee score, to assess functional outcome. At two years post-operatively 60 patients were available for assessment, 30 in each group and 62 patients completed a postal survey. No patient in either group had undergone revision. All variables were analysed for differences between the groups either by Student’s The clinical outcome of the patients with a computer-navigated knee replacement appears to be no different to that of a more conventional jig-based technique at two years post-operatively, despite the better alignment achieved with computer-navigated surgery.
Introduction. Patellar tracking in total knee replacements has been extensively studied, but little is known about patellar tracking in isolated patellofemoral replacements. We compared patellar tracking and the position of the patellar groove in the natural knee, followed by implantation of the femoral component of a PFR (patella unresurfaced) and after implantation of the femoral & patellar component of the PFR. Methods.
We have investigated the accuracy of placement of the femoral component using imageless navigation in 100 consecutive Birmingham Hip Resurfacings. Pre-operative templating determined the native neck-shaft angle and planned stem-shaft angle of the implant. The latter were verified post-operatively using digital anteroposterior unilateral radiographs of the hip. The mean neck-shaft angle determined before operation was 132.7° (118° to 160°). The mean planned stem-shaft angle was a relative valgus alignment of 9.7° ( Navigation in hip resurfacing may afford the surgeon a reliable and accurate method of placement of the femoral component.
Stereotactic principles used primarily for brain surgery have been developed further and introduced into spine surgery at the beginning of the 1990’s. The system solutions available consist of three components: the surgical object (vertebra), the virtual object (CT-image data of the vertebra), and the navigatorallowing the surgeon to localise the position of the instrument inside the surgical object in real-time. Optoelectronic systems using infrared light emitting diodes and magnetic field based navigators are in use. Lumbar pedicle screw insertion was the first clinical application for this technique. Screws can be positioned safely following a preplanned optimal trajectory or according to the anatomic situation utilising the real-time module intraoperatively. The effectiveness of this new technique has been shown in prospective studies (Schwarzenbach et al 1997, Laine et al 1997, 1999). In a a prospective randomised clinical trial one-hundred consecutive patients were randomly allocated for either conventional (Group 1) or computer assisted (Group 2) pedicle screw insertion. From the computer assisted group nine patients were dropped out. There was no statistical difference between the groups. CT-based optoelectronic navigation was used for screw insertion in Group 2. The screw position in the pedicle was assessed postoperatively by an independent observer with CT. The pedicle perforation rate was 13.4% (37/277 screws) in the conventional group and 4.6% (10/219 screws) in the computer assisted group (P=0.006). The majority of perforations was less than 4 mm. A pedicle perforation of 4 to 6 mm was found in 1.4% (4/277) of the screws in Group 1, and none in Group 2. Intraoperatively, eleven screws were repositioned in Group 1 and none in Group 2. There were no postoperative complications related to screw placement. We conclude that higher accuracy of pedicle screw insertion with
Introduction:
We compared lower limb coronal alignment measurements
obtained pre- and post-operatively with long-leg radiographs and
computer navigation in patients undergoing primary total knee replacement
(TKR). A series of 185 patients had their pre- and post-implant
radiological and computer-navigation system measurements of coronal alignment
compared using the Bland-Altman method. The study included 81 men
and 104 women with a mean age of 68.5 years (32 to 87) and a mean
body mass index of 31.7 kg/m2 (19 to 49). Pre-implant
Bland–Altman limits of agreement were -9.4° to 8.6° with a repeatability
coefficient of 9.0°. The Bland–Altman plot showed a tendency for the
radiological measurement to indicate a higher level of pre-operative
deformity than the corresponding navigation measurement. Post-implant
limits of agreement were -5.0° to 5.4° with a repeatability coefficient
of 5.2°. The tendency for valgus knees to have greater deformity
on the radiograph was still seen, but was weaker for varus knees. The alignment seen or measured intra-operatively during TKR is
not necessarily the same as the deformity seen on a standing long-leg
radiograph either pre- or post-operatively. Further investigation
into the effect of weight-bearing and surgical exposure of the joint
on the mechanical femorotibial angle is required to enable the most appropriate
intra-operative alignment to be selected.
Tibial cut is a crucial step in ensuring adequate and appropriate proximal tibial resection for mechanical orientation and axis in total knee replacement. We evolved the concept and technique of Condylar Differential for planned tibial cuts in conventional total knee replacement, which accounts for individual variations and reflects individual mechanical orientation and alignment. We used Condylar Differential in 37 consecutive total knee replacements including valgus knees and severe advanced osteoarthritis. First a vertical line is drawn on digital weight bearing anteroposterior radiograph for mechanical axis of tibia. Then a horizontal line is drawn across and perpendicular to the mechanical axis. The distances between the horizontal line and the lowest reproducible points of articular surfaces of medial and lateral tibial condyles respectively are measured. The difference between two measurements obviously represents Condylar Differential. Condylar Differential, adjusted to the nearest millimetre, is maintained in executing tibial cuts, successively if necessary. Condylar Differential measurement showed a very wide variation, ranging from 8–6 (2 mm) to 10-0 (10 mm). We found that prior measurement of Condylar Differential is a simple, consistent and effective estimate and individualises the tibial cut for optimal templating of tibia. We encountered no problems, adopting this technique, in our series. Condylar Differential contributes to optimal individualised tibial cut in conventional total knee replacement and is a useful alternative to computer navigated option with comparable accuracy in this respect. While we used the technique in digitised radiographs, this technique can also be applied to plain films, allowing for magnification.
The computed neck-shaft angle and the size of the femoral component were recorded in 100 consecutive hip resurfacings using imageless computer-navigation and compared with the angle measured before operation and with actual component implanted. The reliability of the registration was further analysed using ten cadaver femora. The mean absolute difference between the measured and navigated neck-shaft angle was 16.3° (0° to 52°). Navigation underestimated the measured neck-shaft angle in 38 patients and the correct implant size in 11. Registration of the cadaver femora tended to overestimate the correct implant size and provided a low level of repeatability in computing the neck-shaft angle. Prudent pre-operative planning is advisable for use in conjunction with imageless navigation since misleading information may be registered intraoperatively, which could lead to inappropriate sizing and positioning of the femoral component in hip resurfacing.
Mechanics and kinematics of the knee following total knee replacement are related to the mechanics and kinematics of the normal knee. Restoration of neutral alignment is an important factor affecting the long-term results of total knee replacement. Tibial cut is a vital and crucial step in ensuring adequate and appropriate proximal tibial resection, which is essential for mechanical orientation and axis in total knee replacement. Tibial cut must be individually reliable, reproducible, consistent and an accurate predictor of individual anatomical measurements. Conventional tibial cuts of tibia with fixed measurements cannot account for individual variations. While computer navigated total knee replacement serves as a medium to achieve this objective, the technology is not universally applicable for differing reasons. Therefore we evolved the concept and technique of Condylar Differential for planned tibial cuts in conventional total knee replacement, which accounts for individual variations and reflects the individual mechanical orientation and alignment. We used the Condylar Differential in 37 consecutive total knee replacements. We also applied the technique in valgus knees and severe advanced osteoarthritis. First a vertical line is drawn on the digital weight bearing anteroposterior radiograph for mechanical axis of tibia. Then a horizontal line is drawn across and perpendicular to the mechanical axis of tibia. The distances between the horizontal line and the lowest reproducible points of the articular surfaces of the medial and lateral tibial condyles respectively are measured. The difference between the two measurements obviously represents the Condylar Differential. Condylar Differential, adjusted to the nearest millimeter, is maintained in executing the tibial cuts, if necessary successive cuts.Background
Methods
We have developed a CT-based navigation system using infrared light-emitting diode markers and an optical camera. We used this system to perform cementless total hip replacement using a ceramic-on-ceramic bearing couple in 53 patients (60 hips) between 1998 and 2001. We reviewed 52 patients (59 hips) at a mean of six years (5 to 8) postoperatively. The mid-term results of total hip replacement using navigation were compared with those of 91 patients (111 hips) who underwent this procedure using the same implants, during the same period, without navigation. There were no significant differences in age, gender, diagnosis, height, weight, body mass index, or pre-operative clinical score between the two groups. The operation time was significantly longer where navigation was used, but there was no significant difference in blood loss or navigation-related complications. With navigation, the acetabular components were placed within the safe zone defined by Lewinnek, while without, 31 of the 111 components were placed outside this zone. There was no significant difference in the Merle d’Aubigne and Postel hip score at the final follow-up. However, hips treated without navigation had a higher rate of dislocation. Revision was performed in two cases undertaken without navigation, one for aseptic acetabular loosening and one for fracture of a ceramic liner, both of which showed evidence of neck impingement on the liner. A further five cases undertaken without navigation showed erosion of the posterior aspect of the neck of the femoral component on the lateral radiographs. These seven impingement-related mechanical problems correlated with malorientation of the acetabular component. There were no such mechanical problems in the navigated group. We conclude that CT-based navigation increased the precision of orientation of the acetabular component and control of limb length in total hip replacement, without navigation-related complications. It also reduced the rate of dislocation and mechanical problems related to impingement.
We hypothesised that the use of computer navigation-assisted
surgery for pelvic and sacral tumours would reduce the risk of an
intralesional margin. We reviewed 31 patients (18 men and 13 women)
with a mean age of 52.9 years (13.5 to 77.2) in whom computer navigation-assisted
surgery had been carried out for a bone tumour of the pelvis or
sacrum. There were 23 primary malignant bone tumours, four metastatic
tumours and four locally advanced primary tumours of the rectum.
The registration error when using
Total knee arthroplasty (TKA) has become one of the most successful procedures in orthopedics, and its survival rates are reportedly greater than 90% after 15 years. Malpositioning of the component, however, can lead to various failures, such as aseptic loosening, instability, polyethylene wear, and patellar dislocation. Navigation systems for TKA have been developed to improve postoperative alignment. Many clinical and experimental studies of these navigation systems have shown that the accuracy of implanted components has improved. We have compared the alignment of 150 total knee replacements implanted using a computed tomography-based navigation system and using the conventional alignment guide system when performed by a single surgeon. The knees were evaluated using full-length weight-bearing anteroposterior radiographs and computed tomography scans. For the navigated group, the average hip-knee-ankle angle, the femoral component angle to the femoral mechanical axis, and the tibial component angle to the mechanical tibial axis were 179.5, 89.4 and 89.7 degrees. The rotational femoral and tibial component angles to the planning axis were 0.6 and 0.3 degrees. The ideal angles of all alignments in the navigated group were obtained at significantly higher rates than in the conventional group. Our results demonstrated significant improvements in component positioning with CT-based navigation system, especially with respect to rotational alignment. Recently, we established a new method for 3D reconstruction from postoperative CT images in order to accurately measure the alignment of the component relative to any designed plane. The results showed that the discrepancy between the two-dimensional and three-dimensional evaluations was 0.3 ± 1.8 (−2.7–3.4) degrees. The coronal femoral angle for 36 knees (97.3%) and the coronal tibial angle for all the 37 knees (100%) were obtained within 3 degrees from the optimal angle. It is possible to measure the postoperative alignment for TKA more accurately on the basis of the defining plane. Three-dimensional analysis is necessary to evaluate the accuracy of the navigation system. We conclude that navigation system is a very useful tool for achieving proper postoperative alignment. Controversy still exists regarding accuracy in rotational alignment with image-free navigation, but our results showed that CT-based system significantly improved accuracy of rotational alignment. We should keep using and improving the systems to establish more simplified and accurate systems.
Computer aided joint replacement surgery is being used increasingly. It is more commonly used at present in the knee replacement surgery as compared to hip replacement arthroplasty. It is still under developmental phase. The published literature shows there is increased accuracy of the component placement of acetabular cup and femoral stem. We describe the technique for the Stryker navigation system as used in total hip arthroplasty. The technique used by us presently is an active tracker system. This is a both way communication system of infrared waves between the trackers and the sensors. The trackers are fixed to the bones, then the registration of patient specific anatomy is done and hip arthroplasty is performed with aid of the
The KneeAlign2 (OrthAlign, Inc., Aliso Viejo, CA) is a portable accelerometer-based navigation device for use in performing the distal femoral resection in total knee arthroplasty (TKA). This device works as a computer-assisted surgical system. It does not require the use of a large console for registration and alignment feedback.(image1,2) The aim of this study was to investigate the accuracy in positioning the femoral component and the presense of a learning curve in conducting TKA using this device.Introduction
Purpose
The surgical management of musculoskeletal tumours is a challenging problem, particularly in pelvic and diaphyseal tumour resection where accurate determination of bony transection points is extremely important to optimise oncologic, functional and reconstructive options. The use of
The surgical management of musculoskeletal tumours is a challenging problem, particularly in pelvic and diaphyseal tumour resection where accurate determination of bony transection points is extremely important to optimise oncologic, functional and reconstructive options. The use of
Background. The surgical management of musculoskeletal tumours is a challenging problem, particularly in pelvic and diaphyseal tumour resection where accurate determination of bony transection points is extremely important to optimise oncologic, functional and reconstructive options. The use of
Introduction: Obesity [Body Mass Index (BMI) >
30] is seen in a growing percentage of patients seeking joint replacement surgery. Recent studies have shown no clear influence of obesity on the five-year, clinical outcome of total knee replacement; except for the morbidly obese (BMI >
40).
Resection of sacral chordoma remains challenging because complex anatomy and important nerves in the sacrum make it difficult to achieve wide surgical margins. Computer-assisted navigation has shown promise in aiding in optimal preoperative planning and in providing accurate and precise tumour resection during surgery. To evaluate the benefit of using computer-assisted navigation in precise resection of sacral chordoma.Background
Purpose
Background. Limb length discrepancy after total hip replacement is one of the possible complications of suboptimal positioning of the implant and cause of patients dissatisfaction.
Differences of dynamic (extension vs. flexion) coronal alignment in osteoarthritic (OA) knees undergoing primary total knee arthroplasty (TKA) remain poorly studied. Prospectively collected measurements of dynamic coronal alignment using an imageless computer-navigation system (Stryker©) during primary TKA were analysed. Coronal alignment was represented by the hip-knee-ankle angle and determined at maximal extension and 90° flexion before making any bony cuts or ligamentous releases. Measurements were subgrouped according to coronal alignment in extension as varus (≤-3°), neutral (>−3°, <+3°) or valgus (≥+3°).Background
Methods
Restoration of the native joint line in total knee arthroplasty is important in restoring ligamentous balance and normal knee kinematics. Failure to achieve this could lead to reduced range of motion, patellofemoral maltracking and suboptimal outcomes. The purpose of this study was to analyse the clinical and functional outcome of patients who demonstrated joint line changes after computer-assisted (CAS) total knee arthroplasty (TKA). A prospective study was conducted for 168 patients (168 knees) who underwent CAS TKA by two surgeons at a single institution with an average follow-up of two years. The final change in joint line was calculated from the verified tibial resection, distal and posterior femoral cuts. Group A patients had joint line changes of less than 4mm and Group B patients had joint line changes of more than 4mm. Postoperative Oxford scores, Knee scores, Function scores and SF-36 scores were obtained at six months, one year and two years post-TKA. The final range of motion and the mechanical alignment were documented. There was significant linear correlation between joint line changes and Oxford scores (p = 0.05) and Function scores (p = 0.05) at six months and Oxford scores alone at two years with increasing joint line changes having poorer outcome scores. Group A compared to Group B patients have better outcomes in terms of Oxford scores (mean 20 vs 27, p = 0.0003), Function scores (mean 69 vs 59, p = 0.03), SF-1 (mean 63 vs 50, p = 0.03), SF-2 (mean 66 vs 43, p = 0.05), SF-5 (mean 75 vs 63, p = 0.04), SF-6 (mean 84 vs 59, p = 0.003), SF-7 (mean 96 vs 83, p = 0.02), SF-8 (mean 84 vs 73, p = 0.006) and total SF-36 scores (mean 603 vs 487, P = 0.003), at six months, and Oxford scores (mean 18 vs 23, p = 0.0007) at two years. In this study, CAS is a useful intra-operative tool for assessing the final joint line in TKA. Outliers in joint line changes of ≥ 4 mm are associated with poorer clinical outcome scores.
Opening-wedge High Tibial Osteotomy (HTO) has been shown to be an effective procedure to treat mild to moderate osteoarthritis of the medial compartment of the knee in active individuals. It has also become a mandatory surgical adjunct to articular cartilage restoration when there is preoperative mal-alignment. However, its efficacy is directly correlated with the accuracy of the correction, which must be within 3° of the preoperative target. Achieving this goal is a significant challenge with conventional techniques. Therefore, computer-assisted navigation protocols have been developed; however, they do not adequately address the technical difficulties associated with this procedure. We present an integrated solution dedicated to the opening-wedge HTO. Advantages to the technique we propose include: 1) a minimum number of implanted bone trackers, 2) depth control of the saw, 3) improved 3-D accuracy in the location of the lateral tibial hinge, and 4) micrometric adjustment of the degree of correction. The proof of concept has been completed on all six specimens. The following key points have been validated: a) Compatibility with a minimally-invasive (5–6 cm) surgical incision b) The compact navigation station can be placed close to the operative field and manipulated through a sterile draping device c) Only two trackers are necessary to acquire the required landmarks and to provide 3-D control of the correction. These can be inserted within the surgical wound without any secondary incisions d) The optimised guide accurately controlled the external tibial hinge in all six cases e) The implant cavity could be milled effectively f) The distractor used to complete the desired realignment maintained stability of the distraction until final fixation with the PEEK implant g) The PEEK implant could be fixed to the tibia with excellent stability in a low-profile fashion. The solution presented here has the potential to help surgeons perform a medial opening-wedge HTO more safely and accurately. This will likely result in an increase in the number of HTOs performed for both isolated medial compartment osteoarthritis as well as for lower extremity realignment in association with cartilage restorative procedures.
Introduction: The knee joint replacement arthroplasty is a very successful procedure. Traditionally we aim to perform the arthroplasty and recreate the patients’ biomechanical axis and correct the coronal plain alignment deformity. Unfortunately till recently there was no fine way of controlling the exact alignment and depending on surgeon to surgeon, a valgus (to anatomical axis) of 3 to 7 degrees is aimed for using mechanical intra or extramedullary jigs. On proper measurements only 70–80% of knees achieve the aimed result at best as can be seen in the literature. With the advent of
Femoral intramedullary canal referencing is utilized by most of the total knee arthroplasty (TKA) systems. Violation of the canal is performed in order to engage rod instruments in the femoral diaphysis and to refer of the anatomical axis of the femur. Fat embolism, activation of the coagulation cascade, and bleeding may occur from the reamed femoral canal. The purpose of our study was to validate a new set of _minimally-invasive friendly_ instruments which allow to prepare the femur without violating the intramedullary canal. Twenty-five consecutive patients undergoing primary TKA through a mini-subvastus approach were enrolled in the study after informed consent had been obtained. Results of this cohort (group 1) were compared to another contemporary group (group 2) of 25 TKAs operated by the same surgeon using intramedullary instruments. The two groups were matched for gender, deformity, degree of arthritis, and surgical approach. Reliability of the new extramedullary set of instruments was first tested in ten cadaveric limbs. Preoperative long weight-bearing AP and lateral view of the knee were obtained taking care of neutral limb positioning. Template of the mechanical and anatomical axis were performed. Distal femoral resection was planned according to the template, and considering a bone cut perpendicular to the mechanical axis of the femur. Measurement from the template were reproduced on the distal femoral cutting jig. Flexion-extension control of the distal femoral resection was obtained using the anterior meta-diaphyseal cortex reference. Depth of resection, and varus-valgus angulation were selected according to the previous measurements and referring over the most prominent distal femoral condyle. A double check was performed using an extra-medullary rod referring two and a half finger-breaths medially to the antero-superior iliac spine. Postoperative blood loss, pain, swelling, functional recovery, and complications were recorded. Radiographic alignment was measured with long film. Mechanical axis was within 0±2° in 88% of group 1 and 84% of group 2 (p>
0.05). There were no difference between the two groups regarding the operative time. In group 1, postoperative blood loss (740 vs 820 mL) was reduced but this difference did not reach the statistical significance (p=0.07). No difference was found in terms of postoperative pain, knee swelling, and functional recovery. Extramedullary reference with careful preoperative templating can be safely utilized during total knee arthroplasty. Avoiding the violation of the femoral canal may enhance the benefits of a less invasive approach.
Aim: To test the accuracy of implant positioning in using
Aim: To test the accuracy of implant positioning in using
Over the last two decades, anatomic anterior cruciate ligament (ACL) reconstructions have gained popularity, while the use of extraarticular reconstructions has decreased. However, the biomechanical rationale behind the lateral extraarticular sling has not been adequately studied. By understanding its effect on knee stability, it may be possible to identify specific situations in which lateral extraarticular tenodesis may be advantageous. The primary objective of this study was to quantify the ability of a lateral extraarticular sling to restore native kinematics to the ACL deficient knee, with and without combined intraarticular anatomic ACL reconstruction. Additionally, we aimed to characterise the isometry of four possible femoral tunnel positions for the lateral extraarticular sling. Eight fresh frozen hip-to-toe cadavers were used in this study. Navigated Lachman and mechanised pivot shift examinations were performed on ACL itact and deficient knees. Three reconstruction strategies were evaluated: Single bundle anatomic intraarticular ACL reconstruction, Lateral extraarticular sling, Combined intraarticular ACL reconstruction and lateral extraarticular sling. After all stability tests were completed, we quantified the isometry of four possible femoral tunnel positions for the lateral extraarticular sling using the Surgetics navigation system. A single tibial tunnel position was identified and digitised over Gerdy's tubercle. Four possible graft positions were identified on the lateral femoral condyle: the top of the lateral collateral ligament (LCL); the top of the septum; the ideal tunnel position, as defined by the navigation system's own algorithm; and the actual tunnel position used during testing, described in the literature as the intersection of the linear projections of the LCL and the septum over the lateral femoral condyle. For each of the four tunnel positions, the knee was cycled from 0 to 90® of flexion and fiber length was recorded at 30® intervals, therefore quantiying the magnitude of anisometry for each tunnel position. Stability testing: Sectioning of the ACL resulted in an increase in Lachman (15mm, p = 0.01) and mechanised pivot shift examination (6.75mm, p = 0.04) in all specimens compared with the intact knee. Anatomic intraarticular ACL reconstruction restored the Lachman (6.7mm, p = 3.76) and pivot shift (−3.5mm, p = 0.85) to the intact state. With lateral extraarticular sling alone, there was a trend towards increased anterior translation with the Lachman test (9.2mm, p = 0.50). This reconstruction restored the pivot shift to the intact state. (1.25mm, p = 0.73). Combined intraarticular and extraarticular reconstruction restored the Lachman (6.2mm, p = 2.11) and pivot shift (−3.75mm, p = 0.41) to the intact state. There was no significant difference between intraarticular alone and combined intraarticular and extraarticular reconstruction. (p = 1.88) Isometry: The ideal tunnel position calculated by the navigation system was identified over the lateral femoral condyle, beneath the mid-portion of the LCL. The anisometry for the ideal tunnel position was significantly lower (5.9mm; SD = 1.8mm; P<0.05) than the anisometry of the actual graft position (14.9mm; SD = 4mm), the top of the LCL (13.9mm; SD = 4.3mm) and the top of the septum (12mm; SD = 2.4mm). In the isolated acute ACL deficient knee, the addition of a lateral extraarticular sling to anatomic intraarticular ACL reconstruction provides little biomechanical advantage and is not routinely recommended. Isolated lateral extraarticular sling does control the pivot shift, and may be an option in the revision setting or in the lower demand patient with functional instability. Additionally, the location of the femoral tunnel traditionally used results in a significantly more anisometric graft than the navigation's system mathematical ideal location. However, the location of this ideal tunnel placement lies beneath mid-portion of the fibers of the LCL, which would not be clinically feasible.
Tibial and femoral loosening are major causes for implant failure in total knee arthroplasty. Jefferey (1991) reported a significantly lower rate of loosening when varus or valgus was within 3 degrees of mechanical axis in an eight year follow up. Coulle (Dec1999) reported 48% unacceptable alignment in non-navigated knees and Reed (Aug 2002) reported 35% alignments deviating more than 3 degrees from mechanical axis when navigation was not used. We report our series of 286 navigated knee replacements using the Aesculap Search system (21 cases) and the Aesculap e-motion versions 4.2, 4.3 and 4.4 (265 cases) between April 2003 and December 2012 by the author (A.D) and analysed the correction achieved against the zero mechanical axis. Postoperative measurement of the angles on long length films was done in 23 cases. This matched with the intraoperative corrections achieved as studied using per-operative computer data stored for every case. We continued to use the data stored in the AESCULAP System to correlate the findings in the rest of the cases. The average mechanical axis achieved was 1.3 degrees. All cases had mechanical axes within 3 degrees. We were thus able to achieve a high level of correction of the mechanical axes predictable to achieve better clinical outcomes.
Hypothesis. Custom cutting blocks can produce similar alignment compared to computer navigated and conventional total knee arthroplasty (TKA) techniques. Method. We conducted a retrospective review of 37 patients who underwent TKA by a single surgeon in a teaching hospital setting. Groups were conventional method (10),
Several authors have reported that Computer-Assisted Surgery (CAS) can improve limb and prosthesis alignment and ligament balancing in total knee arthroplasty (TKA) and permit the use of a less invasive surgical procedure. This can have a positive impact on the time of recovery of patients. In order to evaluate the real impact on the final outcome of CAS in TKA, we conducted a prospective control study comparing the outcome of computer-assisted and conventional TKAs. We analyzed 60 primary TKAs, randomly divided into two cohorts -group 1 = STD (standard instrumentation) and group 2 = CAS -over three consecutive years. Both cohorts included 30 cases, all affected by primary knee osteoarthritis. The same model of prosthesis was implanted in all cases, by one surgeon, using the same surgical technique. Two patients were bilateral: in both cases one side was treated with standard instrumentation and the other with CAS. We conducted a clinical evaluation at the pre-operative moment and at the consecutive Follow-Up (FU), using the American Knee Society Score (AKSS). We scored patient satisfaction using the Oxford and the Ranawat Center questionnaire. We also recorded the main intra-operative data, such as total blood loss, surgical time, tourniquet time, Range of Motion (ROM). Finally, we performed a radiological study analyzing the pre-operative and consecutive FU radiographs to obtain a quantitative evaluation of limb and prosthesis alignment. The intra-operative blood loss was higher in patients of group STD, with an average difference of 127 ml, statistically significant (p = 0.0283). Component position was acceptable for all implants, but the mechanical axe error of the CAS group was (1.00 +/−0.20) degrees, significantly less than that of the STD group (2.10 +/−0.50) degrees. The mean coronal femoral alignment was 90.00 degrees (range, 89 −92 degrees) in the CAS group, and 91.00 degrees (range, 88 −93 degrees) in the STD group. The operating time of the CAS group was longer than that of the STD group, with an average time difference of 26 minutes, statistically significant [ P = 0.005]. The AKSS and the Oxford and the Ranawat Center questionnaire analysis revealed a faster rehabilitation and an earlier return to daily life activities in the CAS group, independent of the preoperative level of disability. We conclude that the use of navigation in TKA increases accuracy in limb and implant alignment and improves the rehabilitation phase. By achieving more reliable artificial joint implantation, CAS can improve prosthesis duration and joint function. It, however, needs more operating time.
Efforts continue to reduce blood loss in total knee arthroplasty (TKA). Computer assisted surgery (CAS) has been shown to reduce outliers in component position and improve functional outcomes in TKA, yet few studies have reported specifically on blood loss. The primary study objective was to determine whether a modern abbreviated CAS protocol would reduce blood loss in TKA compared to conventional instrumentation. A secondary objective was to assess the effect of CAS on cost and surgical efficiency. A retrospective cohort study of 100 consecutive patients was performed comparing an abbreviated and modern CAS protocol versus conventional IM instrumentation. All TKAs utilized an identical surgical technique without any hemostatic agent. Blood loss was determined using drain output, change in hemoglobin, and calculated blood loss. Tourniquet times were recorded as an indicator of procedural efficiency. A cost analysis compared the CAS protocol to the cost associated with tranexamic acid (TXA) to reduce blood loss and long-leg alignment radiographs to optimize component position.Introduction:
Methods:
Introduction. Total hip arthroplasty has become an increasingly common procedure. Improper cup position contributes to bearing surface wear, pelvic osteolysis, dislocations, and revision surgery. The incidence of cup malposition outside of the safe zone (40° ± 10° abduction and 15° ± 10° anteversion) using traditional techniques has been reported to be as high as 50%. Our hypothesis is that
Background: Computer Assisted Orthopaedic Surgery continues to evolve. Electromagnetic
The Vector Vision CT free navigation system of Brain-Lab (Heimstetten, Germany) for total knee arthroplasty incorporates a ligament balancing feature which allows recording of flexion extension gaps and clinical alignment [3]. Since routine spacer blocks do not necessarily load the joint space symmetrically, if either the bone cuts are asymmetric or the ligaments are not evenly balanced, a tensioning device that applies a constant load to the medial and lateral joint space separately and which can collapse or expand on each side independently should be able to provide a better evaluation of ligament tension and allow the computer software to better plan the appropriate bone cuts or ligament release. The tensioning device comprises 2 linked plates contacting the femur and tibia separated by two independent springs in the medial and lateral compartments. It can be positioned precisely in the joint with the navigation system and, with respect to spacer blocks, this device was designed in order to allow a dynamic evaluation of joint stiffness during all range of motion and, thanks to it’s reduced dimensions, with patella in situ. The springs apply a consistent known force on the compartments, while at the same time the gap produced by the applied forces is measured by the navigation. This study integrates previous article [1] on the validation of the tensioning device and reports the first phase of the clinical validation of the tensioning device, including first qualitative comparison with standard navigated technique and consideration on the use of the device. A spring loaded mechanical device was designed with a constant 6kg load in the springs for each compartment. For the clinical evaluation, the device was inserted into flexion and extension spaces after the tibial cut was performed in routine computer assisted total knee arthroplasty. The gap produced by the applied forces is measured, by the navigation system, as the distance between tibial cut and most distal points on condyles in extension or most posterior points on condyles in flexion. Under the same conditions a set of solid spacer blocks were inserted to obtain a gap able to balance the knee according to surgeon’s sensitivity. This gap was used as reference and compared with the gap obtained with the spring device. The clinical evaluation was performed in order to determine whether there was a difference between the gaps as indicated by both the tensioning device and the spacer blocks. Five experienced orthopaedic surgeons were involved in a randomized study producing 58 complete data sets. Eight measurements (medial and lateral gap, in flexion and extension for tensioning device and spacer blocks) were taken intra-operatively using the ligament balancing features of the VectorVision system. Because many of the measurements were not normally distributed, nonparametric statistical tests (Mann-Whitney and Wilcoxon) were chosen to look for statistical differences, looking for differences in medians and ranking of data instead of differences in averages and distributions. Repeatability of measurements performed with the spring device was defined as the occurrence of same values obtained with the device and by surgeons with spacer blocks. Since the uncertainty in the measurements, due to optical navigation system is near, differences within a range of ±1mm were considered the same value, moreover data within a range of ±2mm were considered a positive result. This data was analyzed with Minitab software version 13.31. Results are reported in Tab.1. Results: extension Flexion compartment Medial lateral medial lateral average difference 0.2 (±2.5 mm) 0.0 (±3.6 mm) 1.3 (±2.1 mm) 1.4 (±2.5 mm) number of cases 57 100 57 100 57 100 57 100 median ±1mm 30 52.6 24 42.1 34 59.6 23 40.4 median ±2mm 43 75.4 36 63.2 47 82.5 36 63.2 Table.1. Average difference between gaps obtained with tensioning device and spacer blocks, and related occurrences in medial\lateral compartments inflexion and extension. Difference between the tensioning device and the spacer blocks in flexion is 0.2mm medially and 0.0mm laterally, while in flexion it is 1.3mm medially and 1.6mm laterally, moreover the alignments of resulting femoral cuts obtained with spring device can be considered the same of the alignments obtained with spacer blocks (difference is <
1°). Data, summarized in Tab.1, highlight that knee has a different behaviour in flexion and extension. Applying the same force with the tensioning device the resulting gap in extension (10mm medial, 10.5mm lateral) is lower than the one flexion (10.5mm medial, 12.5 lateral). The percentage of values around the average in the range of 1mm is 52.6% – 59.6% medially and 40.4% – 42.1% laterally, showing a higher variability on lateral compartment, while the percentage of values in a range of 2mm is75.4% – 82.5% medially and 63.2% laterally, confirming the variability. Determining the soft tissue balance in total knee replacement is important to proper reconstruction. Traditional spacer blocks are unable to load the medial and lateral joint space independently which may compromise the surgical plan. A tensioning device which loads the-joint space independently with a constant load should theoretically allow proper planning of the bone resections and ligament releases during reconstructive surgery. The spring loaded tensor device coupled with image navigation and compared to independent spacer blocks performed by different surgeons revealed that there is no statistical difference between the gaps obtained with spacer blocks and tensioning device in extension, while in flexion there is an average difference 1.4mm, it revealed also that there was greater surgeon variability in the use of spacer blocks compared to the tensioning device. Furthermore, the device produced results that were similar to the results obtained by the spacer blocks especially when surgeon’s variation in technique was taken into account. The use of a joint tensioning device, coupled with computer assisted surgery, allows planning appropriate bone resection and ligament releases to produce matched medial and lateral joint spaces in flexion and extension. There were no reports, either inter-operatively or post-operatively, of any complications or adverse events nor any malfunctions of the device. On a number of occasions it was felt necessary to perform additional bone resections to allow the insertion of the spring device. However this should be considered as a normal part of TKA and of the inter-operative decision making process. This data also revealed, as would be expected clinically that the joint space is less in extension than in flexion after the tibial cut is performed [3]; surgeons with the help of spacer blocks apply less force in flexion in order to obtain the same gap during range of motion, the spring device, applying always the same force, is opening the joint more in flexion. Furthermore, when evaluating the lateral joint space, the tensioning device has a greater variability than the spacer blocks [4]. In this series of patients, a spring loaded tension device decreased surgeon variability in the assessment of ligament tension and, when coupled with
Despite the well-documented improvement in coronal alignment achieved by