Computer-assisted total knee arthroplasty for arthritis with extra-articular deformity

Is mid-sulcus line a predictive guide for tibial mechanical axis during total knee arthroplasty?

BACKGROUND

Achieving appropriate alignment of components in total knee arthroplasty (TKA) is essential for optimal functional outcomes as well as implant longevity. Performing TKA in the absence of a computer-assisted navigation system (CANS) mandates the use of accurate anatomical landmarks for achieving appropriate alignment. In this study, we have evaluated the reliability of 'mid-sulcus line' as an anatomical landmark to guide tibial resection, with the intra-operative help of CANS.

METHOD

A total of 322 patients undergoing primary TKA (excluding previously operated limbs and limbs with extra-articular deformities of tibia or femur) using CANS were included in the study. After resecting ACL, the mid-suclus line was drawn with a cautery tip. We hypothesized that if tibial cut was made perpendicular to the mid-sulcus line, coronal alignment of the tibial component would be along the neutral mechanical axis. This was evaluated intra-operatively with the help of CANS.

RESULTS

Of 322 knees, identification of the 'mid-sulcus line' was possible in 312 knees. The mean angle between the tibial alignment defined by mid-sulcus line and the neutral mechanical axis was found to be 0.45° (range, 0-1.5°) (P < 0.05). In all of the 312 knees, the tibial alignment defined by mid-sulcus line was found to be within 3° of the neutral mechanical axis (confidence interval: 0.410°, 0.491°).

CONCLUSION

Mid-sulcus line can be used as an additional anatomical landmark to guide the tibial resection and thereby achieve appropriate coronal alignment in primary TKAs without any extra-articular deformity.

Femoral bowing affects varus femoral alignment but not patient satisfaction in mechanically aligned total knee arthroplasty

PURPOSE

This study evaluated whether patients with particular lower limb morphological factors have femoral and tibial component malpositioning during mechanically aligned total knee arthroplasty (TKA) and lower postoperative satisfaction.

METHODS

This study included 146 knees in 117 Asian patients undergoing TKA for medial osteoarthritis. Preoperative bony morphological factors such as the angle between the femoral mechanical and anatomical axes (MA-AA angle), angle between the anatomical axes of the proximal and distal femur (lateral bowing femoral angle, LBFA), mechanical lateral distal femoral angle, medial proximal tibial angle, and % anatomical axis of the tibia were evaluated, as well as preoperative and 1-year postoperative 2011 Knee Society scores (KSSs).

RESULTS

MA-AA angle and LBFA were significantly larger in knees with varus femoral component alignment versus neutral alignment. Preoperative MA-AA angle was underestimated in patients with larger MA-AA angle or LBFA, especially by inexperienced surgeons. Tibial morphological factors did not affect tibial component alignment. Changes in 2011 KSSs were similar among groups by lower limb alignment or femoral and tibial component alignment.

CONCLUSION

Femoral bowing affects varus femoral component alignment by obscuring preoperative planning, but it had little impact on patient satisfaction when mechanical alignment is targeted during TKA.

Accelerometer-Based Navigation versus Conventional Total Knee Arthroplasty for Posttraumatic Knee Osteoarthritis

BACKGROUND

Posttraumatic osteoarthritis (PTOA) frequently comprises femoral or tibial deformity, which makes it difficult to perform total knee arthroplasty (TKA). Accelerometer-based navigation (ABN) could be effective in restoring a neutral mechanical axis (MA) in TKA, but a limited number of studies have been reported in association with PTOA. Therefore, we aimed to compare the lower limb MA between ABN-assisted TKA (ABN-TKA) and conventional TKA in patients with PTOA.

METHODS

We conducted a retrospective analysis of 28 PTOA patients who underwent TKA using a conventional system (cTKA group, n = 16) and the ABN system (iTKA group, n = 12). Standing long-leg radiographs were assessed for MA and prosthesis alignment as primary outcomes. A postoperative MA deviating beyond ± 3° was defined as an outlier. Perioperative outcomes, Oxford Knee Score (OKS) at 2-year follow-up, and complications were also assessed.

RESULTS

The cTKA group and the iTKA group had a mean age of 63.07 years and 65.25 years, respectively. The iTKA group had significantly better MA accuracy when compared to the cTKA group (1.60° ± 2.09° vs. 3.59° ± 1.34°, p = 0.01). The iTKA group showed significantly less MA outlier than the cTKA group (78.6% vs. 25.0%, p = 0.02). The prosthesis alignment and OKS were comparable between the groups. There were 2 periprosthetic joint infections in the cTKA group and 1 periprosthetic fracture of the distal femur in the iTKA group.

CONCLUSIONS

For PTOA of the knee, both conventional TKA and ABN-TKA significantly improved the postoperative mechanical alignment and functional outcomes. The ABN-TKA seemed to offer higher accuracy and less MA outlier when compared to conventional TKA, and thus ABN could be a good alternative option.

Surgical principles for complex primary total knee arthroplasty in the presence of extra-articular deformity

Background

Accurate restoration of alignment is vital to the success of a total knee arthroplasty (TKA) procedure. Deformities, whether these are intra-articular and/or extra-articular AND/OR whether these are uniplanar/multiplanar/complex, can impose varying technical challenges in surgical planning and execution. Literature on performing TKA in presence of limb deformity is limited, especially for extra-articular deformities.

Objectives

The objectives of this narrative review are twofold. Firstly, we analyse the existing English literature for studies focussed on TKA and deformity correction and summarise the important points about deformity pathomechanics, clinical and radiological assessment, pre-operative planning and surgical techniques. The second objective is to provide the readers with a simplistic and wholistic management algorithm to assist surgeons in meticulous planning to tackle the technical challenges imposed by lower limb deformities while performing a TKA.

Discussion

Approach to each patient must be holistic and customised on an individual basis according to patient characteristics, deformity characteristics and surgeon experience. The three main options available are: (1) Primary TKA (symmetric cuts/asymmetric cuts with/without computer navigation assistance) (2) Single stage corrective osteotomy and TKA and (3) Two-staged deformity correction and TKA. A multi-disciplinary team approach is required and a knee surgeon well-versed in revision arthroplasty and a limb reconstruction surgeon specialising in deformity correction, should be involved from the outset. The use of computer navigation technology, particularly for deformity correction and TKA, has increased over the last couple of decades and is recommended by the authors for these challenging cases.

Seven phenotypes of varus osteoarthritic knees can be identified in the coronal plane

PURPOSE

Recommendations for resecting distal femur and proximal tibia in mechanical and anatomical alignment techniques are standardized. Kinematic alignment propagates individualizing resection planes. Whether significant variation exists, to warrant departure from standardized resection planes, has not been shown thus far in a large cohort of knees and with a wide range of varus deformity. The null hypothesis of this study was that there was no phenotypic variation in varus osteoarthritic knees. The aim of this paper was to determine whether distinct phenotypes could be identified, based on variations in coronal femoral and tibial morphology, which could aid in surgical planning and categorizing varus knees for future studies.

METHODS

2129 full-leg weightbearing radiographs were analyzed (1704 preoperative; 425 of contralateral arthritic knee). Measurements made were of HKA (hip-knee-ankle angle), VCA (valgus correction angle), mLDFA (lateral mechanical distal femoral angle), aLDFA (lateral anatomical distal femoral angle), MPTA (medial proximal tibial angle), MNSA (medial neck shaft angle), TAMA (angle between tibial mechanical and anatomical axes), and TPDR (percentage length of tibia proximal to extra-articular deformity).

RESULTS

Seven distinct types were identified covering 2021 knees, reducible to 4 broad phenotypes: 11% were Type 1 'Neutral' knees showing values close to reported normal knees (mean VCA 5.5°, mLDFA 87°, aLDFA 81°). 38% were Type 2 'Intra-articular varus' with medial intra-articular bone loss (mean mLDFA 90.9°, MPTA 85.4°, VCA of 5.7°). 41% were Type 3 'Extra-articular varus' with extra-articular deformity (EAD). Type 3a had proximal tibial EAD; Type 3b had tibial diaphyseal EAD; Type 3c had femoral EAD (mean VCA 8.7°, HKA 166°), and severe medial bone loss (mean mLDFA 92°, MPTA 83°). 9% were Type 4 'Valgoid type' with features of valgus knees: Type 4a had medial femoral bowing (mean VCA 2.9°); Type 4b had significant distal femoral valgus (mean mLDFA 85.3°, aLDFA 78.6°).

CONCLUSIONS

The null hypothesis that there was no phenotypic variation in varus osteoarthritic knees was rejected as considerable variation was found in coronal morphology of femur and tibia. Four broad phenotypic groups could be identified. Plane of the knee joint articular surface was quite variable. This has relevance to planning and performance of corrective osteotomies, unicompartmental and total knee arthroplasty.

LEVEL OF EVIDENCE

III, retrospective cohort study.

Registration of Proximal Tibial Centre May Need to be Selectively Lateralized to Avoid Coronal Malalignment in Digitally-Assisted Knee Arthroplasty

PURPOSE

Placement of prosthetic components and limb alignment can be adversely impacted by errors in identification of registration points in digitally assisted knee arthroplasty. The purpose of this study was to trigonometrically analyze the impact on the accuracy of coronal tibial component and limb alignment of discrepancy between the registered midpoint of the proximal bony tibia vis-à-vis the radiographic medio-lateral center of the lateralized final tibial implant in certain varus-deformed knees.

METHODS

We analyzed trigonometrically the angular difference θ in coronal alignment of tibial component and hip-knee-ankle angle resulting from lateral translation of the medio-lateral center of the final tibial implant, with respect to the initial registered midpoint of the proximal bony tibia. θ was calculated using the equation tan( θ ) = d/t, where d is the numerical distance between the registered point and the center of the final tibial tray position and t is the length of tibia distal to the resection.

RESULTS

One degree of varus malpositioning of the tibial component and the limb can occur for every 6.3 mm of lateral translation of the tibial implant with respect to the midpoint of the proximal bony tibia of average reported length (372 mm). The magnitude of this error is inversely proportional to tibial length and the patient's height.

CONCLUSIONS

Coronal malalignment of the tibial component and the limb is directly proportional to the amount of lateral translation of the tibial tray with respect to the registered midpoint of the proximal bony tibia and inversely proportional to the patient's height. This may occur in cases with tibial extra-articular deformity, those undergoing reduction osteotomy, downsizing of the tray, or inadvertently during tibial preparation. The error can be avoided by initial registration of the tibial midpoint more laterally by templating, re-registering the new center of the resected tibial surface or osteotomy for extra-articular deformity.

Extra-articular tibial deformity management in total knee replacement

BACKGROUND

Presence of an extra-articular deformity in the femur or tibia poses a challenge to the surgeon undertaking knee replacement procedure. The conundrum is whether to correct the deformity beforehand, or accept the deformity and compensate for this through placement of the implant.

MATERIAL AND METHODS

This is a retro-spective study comprising six patients who had a knee replacement in the presence of an extra-articular deformity of the tibia treated at our centre. All six had the knee replacement without correction of deformity. The data evaluated included clinical outcome, mechanical axis correction, type of implant, and the use of any software / computer guidance.

The deformity was managed through planning of tibial resection without the need for pre-operative deformity correction.

RESULTS

Mean age was 66.5 years. Mean coronal plane deformity in the tibia was 8.6 degrees. The hip- knee-ankle improved from a mean 12.6 degrees to 4 degrees. Mean Oxford knee score improved from a mean of 19 to 33.6.

CONCLUSION

Planning the tibial resection on the basis of mechanical axis of tibia allows correction of alignment without the need for preoperative correction.

Correction of the deformity may not be needed if the maximum tibial resection is less than 15 mm.

Handheld computer-navigated constrained total knee arthroplasty for complex extra-articular deformities

INTRODUCTION

The present study aimed to assess the postoperative alignment and clinical outcomes of patients with complex extra-articular deformities (EADs) undergoing computer-assisted surgery (CAS) for constrained total knee arthroplasty (TKA) with modular stem extensions.

MATERIALS AND METHODS

From May 2015 to July 2018, ten patients with EADs scheduled for constrained TKA were enrolled retrospectively. The preoperative average deviation from neutral (= 180°) mechanical axis was 15.3° (range of coronal alignment: 150.9° varus-202.9° valgus). Alignment was assessed using an accelerometer-based handheld CAS system. On long-leg films, the positions of the components and possible stems were analysed and templated preoperatively. The average follow-up was 3.3 years (range: 2.0-4.6 years).

RESULTS

The postoperative mechanical axis was within ± 3.0° from neutral in nine patients. In all patients, the Knee Society score (KSS) and range of motion improved significantly. A constrained condylar and a rotating hinge prosthesis were used in five patients each. In eight patients, the 100-mm cementless stem that was preferred by the authors was found to be unusable for the femur or the tibia in the planning stage. For the femur, a cementless 100-mm stem was used in three, and a cemented 30-mm stem in five patients; a femoral stem was not usable in two patients. For the tibia, a cementless 100-mm stem was used in six, and a cemented 30-mm stem in two patients; a monoblock rotating hinge tibia was used in two patients.

CONCLUSIONS

Complex EADs were excellently managed during constrained TKA implantation using the handheld CAS system. Templating allowed the possible stem lengths to be identified and prevented anatomical conflict with the CAS-configured mechanical alignment. Limb alignment and function improved significantly after surgery. No intra- or postoperative complications occurred.

LEVEL OF EVIDENCE

Level IV, retrospective study.

Can accuracy with the iASSIST navigation be confirmed by assessment? A multi-center prospective randomized controlled trial with independent three-dimensional image assessment

BACKGROUND

iASSIST is one of the novel accelerometer-based navigation systems for total knee arthroplasty (TKA). Although the accuracy of iASSIST compared with conventional instruments has been reported, such evaluations were performed on two-dimensional (2D) images (X-rays). This multi-center prospective randomized controlled trial aimed to assess component positioning between TKA with and without iASSIST by 3D image assessment, and to clarify whether the iASSIST provides any benefit with regard to alignment accuracy.

METHODS

Eighty-three knees with primary knee osteoarthritis were enrolled in this study. iASSIST was used for distal femoral and proximal tibial resection in 42 knees (iA group) and a conventional guide was used in 41 knees (CONV group). At 6 months postoperatively, component alignment was evaluated with 3D images by the independent orthopaedic surgeons, and surgical parameters, range of motion and clinical outcomes were examined.

RESULTS

The rate of knees who have the alignment within 3° of neutral compared with the iA group and CONV group were 92.9% (39/42) vs. 87.8% (36/41) for femur and 76.2% (32/42) vs. 56.1% (23/41) for tibia in the coronal plane, respectively, whereas in the sagittal plane, the rate was 85.7% (36/42) vs. 58.5% (24/41) for femur and 83.3% (35/42) vs. 78.0% (32/41) for tibia, respectively. Compared with the CONV group, the iA group had a significantly improved femoral alignment in the sagittal plane (P = 0.006). There were no clinical or patient-reported differences at 6 months postoperatively.

CONCLUSIONS

The iASSIST provides technically high accuracy in femoral resection at TKA compared with a conventional procedure.

Total knee arthroplasty in femoral bowing: does patient specific instrumentation have something to add? A randomized controlled trial

BACKGROUND

Patient-specific instrumentation (PSI) proponents have suggested the benefits of improved component alignment and reduced outliers. In this randomized controlled trial, we attempted to assess the advantage of using PSI over conventional intermedullary (IM) guides for primary total knee arthroplasty (TKA) with bilateral severe femoral bowing (> 5°). A parallel trial design was used with 1:1 allocation. We hypothesize that PSI would support more accurate alignment of components and the lower-limb axis during TKA with severe femoral bowing in comparison with conventional IM guides.

METHODS

Among 336 patients undergoing bilateral TKAs due to knee osteoarthritis, 29 patients with bilateral lateral femoral bowing of more than 5° were included in this study. Every patient was assigned randomly to PSI on one side and to conventional instrumentation lateralization of the entry point of the femoral IM guide was applied on the other with a goal of neutral mechanical alignment. The assessment of coronal alignment was completed by measuring the hip-knee-ankle (HKA) angle on preoperative and postoperative long film standing radiographs. Coronal and sagittal orientations of femoral and tibial components were assessed on weight-bearing radiographs. The rotational alignment of the femoral component was evaluated using computed tomography.

RESULTS

The postoperative mean ± standard deviation (SD) HKA angle was varus 4.0° (± 2.7°) for conventional technique and varus 4.1° (± 3.1°) for PSI, with no differences between the two groups (p = 0.459). The component orientation showed no significant differences except with respect to the sagittal alignment of the femoral component (p = 0.001), with a PSI mean ± SD flexion of 5.8° (± 3.7°) and a conventional method mean ± SD flexion of 3.2° (± 2.5°), due to the intentional 3° flexion incorporated in the sagittal plane to prevent femoral notching in PSI planning. Computed tomography assessment for rotational alignment of the femoral components showed no difference between the two groups concerning the transepicondylar axis (p = 0.485) with a PSI mean ± SD external rotation of 1.5° (± 1.3°) and conventional mean ± SD external rotation of 1.5° (± 1.6°).

CONCLUSION

PSI showed no advantage over lateralization of the femoral entry for IM guidance.

LEVEL OF EVIDENCE

1 TRIAL REGISTRATION: Registered on US national library of medicine ClinicalTrials.gov ( NCT02993016 ) on December 12^th 2016.

One-Stage Total Knee Arthroplasty Plus Corrective Osteotomy for Osteoarthritis Associated With Severe Extra-articular Deformity

The mainstay for treatment of articular deformity caused by advanced tricompartmental osteoarthritis of the knee is total knee arthroplasty. When this is also associated with an extra-articular deformity, this also must be compensated or corrected. In this scenario, it is essential to achieve an optimal mechanical situation by restoring the anatomical and mechanical limb axes and an adequate soft-tissue balance. These premises are necessary to relieve pain and achieve satisfactory functionality and implant survival over time. A reconstructive single-stage technique is proposed for patients with knee osteoarthritis amenable to arthroplasty and a severe extra-articular deformity, aiming at addressing both problems simultaneously.

Total Knee Arthroplasty in Patients With Extra-Articular Deformity: Restoration of Mechanical Alignment Using Accelerometer-Based Navigation System

BACKGROUND

Total knee arthroplasty (TKA) in patients with post-traumatic extra-articular deformity (EAD) is difficult to manage using conventional instrumentation techniques. In this study, we evaluate whether accelerometer navigation system can be a valuable option to make accurate bone resections and restore the neutral mechanical axis in complex TKA patients with EAD.

METHODS

From May 2015 to June 2017, 18 consecutive TKA were performed in 18 patients with knee osteoarthritis with associated EAD. An accelerometer-based navigation system was used to guide tibial and femoral resection in the coronal and sagittal plane. Postoperative lower limb alignment in coronal plane and component position in coronal and sagittal plane was measured through full-leg weight-bearing X-ray. Clinical score were recorded using the Knee Society Score at the final follow-up.

RESULTS

The mean hip-knee-ankle angle was 0.9° ± 1.4° varus alignment. The coronal alignment of the femoral component was 89.2° ± 1.9°, and the coronal alignment of the tibial component was 89.4° ± 2.1°. The sagittal alignment of the femoral component was 93.2°± 1.9°, and the sagittal alignment of the tibial component was 84.4° ± 3.1°. At the final follow-up, the Knee Society Score was 89 points (range, 82-100), and the functional score was 86.7 points (range, 60-100). No intraoperative and postoperative surgical complications were reported using this technology.

CONCLUSION

Accelerometer-based navigation is accurate in achieving neutral mechanical alignment and optimal implant position after TKA in patients with EAD. This system should be considered a valuable option to the more complex technique of computer navigation or robotic surgery.

Total knee arthroplasty in the varus knee: tips and tricks

Varus knee deformity is very common, and it can be classified according to the severity and reducibility of the deformity. Pre-operative planning is mandatory to obtain a good result. Both clinical and radiological planning should be carefully performed, particularly focused on collateral ligament deficiency. In most of the cases, a postero-stabilized implant is necessary, but in the presence of a varus thrust, a midlevel constrained (MLC) implant may be necessary. Rarely, if a severe extra-articular deformity is present, a femoral osteotomy and a high constrain implant may be necessary. In most of the cases, a standard midline approach can be performed. Soft tissue balancing is crucial, avoiding excessive releases of the medial collateral ligament (MCL). In the presence of severe deformity, more aggressive procedure such as tibial reduction osteotomy or sliding medial epicondyle osteotomy can be performed. In literature, good outcomes are reported for total knee arthroplasty (TKA) in varus deformity. In this manuscript, the available literature on TKA in varus deformity is analyzed, and the preferred surgical techniques of the authors are described.

Primary and Secondary Total Knee Arthroplasty for Tibial Plateau Fractures

The surgical management of tibial plateau fractures can be technically demanding. In younger patients, the mainstay is fixation with cartilage preservation. In older patients with osteoporotic bone, this method has higher rates of fixation failure; in addition, it requires prolonged bed rest or protected weight bearing, which are major challenges in this group. In contrast, total knee arthroplasty performed acutely for primary treatment of tibial plateau fractures has potential advantages for elderly patients, such as immediate stability, early mobilization, and positive functional outcomes with decreased rates of reoperation. Additionally, arthroplasty can be technically challenging in younger patients with previous tibial plateau fractures in whom debilitating posttraumatic arthritis develops. In these patients, old wounds, retained metalwork, bony deficiency, and instability can lead to poorer outcomes and higher complication rates than in routine knee arthroplasty. In both cases, we recommend surgery be performed by experienced arthroplasty surgeons with ample access to a range of implants with varying constraints and the option of stems and augments.

NAVIGATED TOTAL KNEE ARTHROPLASTY FOR OSTEOARTHRITIS WITH EXTRA-ARTICULAR DEFORMITY

Objective

It is difficult to achieve proper alignment after total knee arthroplasty (TKA) in patients with extra-articular deformity (EAD) because of altered anatomical axis and distorted landmarks. As of this writing, only case series have been reported with regard to the usefulness of computer-assisted navigation systems for TKA with EAD. This study therefore compared outcomes in TKA with EAD, with and without navigation.

Methods

Fourteen osteoarthritis patients with EAD due to previous fracture malunion or operations were assessed. Seven TKAs were performed with navigation (navigation group) and another 7 were performed without navigation (manual group). Clinical and radiographic outcomes were compared before and two years after surgery.

Results

The mean postoperative Knee Society function score was significantly higher in the navigation group. No significant difference was found in postoperative range of motion and Knee Society knee score. The rate of outliers in radiographic outcomes tended to be lower in the navigation group.

Conclusion

Better clinical outcomes were achieved in cases in which navigation was used. Computer-assisted navigation is useful in TKA for patients with EAD. Level of Evidence III; Case control study.

Total knee arthroplasties from the origin to navigation: history, rationale, indications

Since the early 1970s, total knee arthroplasties have undergone many changes in both their design and their surgical instrumentation. It soon became apparent that to improve prosthesis durability, it was essential to have instruments which allowed them to be fitted reliably and consistently. Despite increasingly sophisticated surgical techniques, preoperative objectives were only met in 75% of cases, which led to the development, in the early 1990s, in Grenoble (France), of computer-assisted orthopaedic surgery for knee prosthesis implantation. In the early 2000s, many navigation systems emerged, some including pre-operative imagery ("CT-based"), others using intra-operative imagery ("fluoroscopy-based"), and yet others with no imagery at all ("imageless"), which soon became the navigation "gold standard". They use an optoelectronic tracker, markers which are fixed solidly to the bones and instruments, and a navigation workstation (computer), with a control system (e.g. pedal). Despite numerous studies demonstrating the benefit of computer navigation in meeting preoperative objectives, such systems have not yet achieved the success they warrant, for various reasons we will be covering in this article. If the latest navigation systems prove to be as effective as the older systems, they should give this type of technology a well-deserved boost.

Extra-articular deformities in arthritic knees-a grueling challenge for arthroplasty surgeons: An evidence-based update

Critical to the success of a total knee arthroplasty (TKA) is the anatomical alignment. This may appear as a challenge in an extra-articular deformity (EAD) that may be inherent in certain people or result from fracture malunion, congenital disorders, nutritional, metabolic and infective causes. This appraisal aimed at providing the reader with an up-todate overview of the research carried out on, and existent evidence of EAD correction while planning a TKA. We reviewed the current English literature on TKA in extra-articular knee deformities. Among the published data, a common initial approach of mandatory clinical and radiological assessment emerges as an obligatory step while handling cases with EAD. While several methods of managing the deformity and arthritis have been described, a broad division into intra-articular and extra-articular means can be deciphered. The relatively old-school, yet reliable thought process of extra-articular correction allows an all-inclusive restoration of alignment with the inherent complications related to the necessary osteotomy. A cohort of younger and more venturesome surgeons seem inclined towards performing navigated, intra-articular correction for mild to moderate and sometimes, severe deformities. The crux of the matter lies is obtaining a well-balanced knee without violating the all-important cruciates. Restoring the patient’s ambulatory status seems sooner with the intra-articular methods which are also more precise in determining the axes and while removing minimum bone. Greatest satisfaction is accomplished in those with less grotesque, rotationallyaligned knees while meticulously balancing soft-tissues and encouraging earlier weightbearing.

The top 10 arthroplasty articles published in last 10 years by Indian authors

Joint replacement surgery is becoming increasingly popular globally and recently,​in India. The phenomenon of medical tourism has also contributed to increasing number of arthroplasty surgeries being done every year in our country. The surgeons who work in this highly specialized field of orthopedic surgery, have been publishing their research work in reputed journals. In this paper, we have discussed the most cited Indian papers in the field of arthroplasty. It was observed that publications in high impact and reputed journals attract more citations and therefore it is recommended that the 'good' scientific research work should preferably be submitted to these journals to create greater impact and awareness about ones' research.

Usefulness of an accelerometer-based portable navigation system in total knee arthroplasty

Aims

The aim of this study was to evaluate the effects of using a portable, accelerometer-based surgical navigation system (KneeAlign2) in total knee arthroplasty (TKA) on the alignment of the femoral component, and blood loss.

Patients and Methods

A total of 241 consecutive patients with primary osteoarthritis of the knee were enrolled in this prospective, randomised controlled study. There were 207 women and 34 men. The mean age of the patients was 74.0 years (57 to 89). The KneeAlign2 system was used for distal femoral resection in 121 patients (KA2 group) and a conventional intramedullary femoral guide was used in 120 patients (IM group).

Results

One patient (0.8%) in the KA2 group and 19 in the IM group had an alignment which was > 3° away from the neutral mechanical axis (p < 0.01). The mean deviation from neutral alignment was 1.01° (standard deviation (sd) 1.0°) in the KA2 group and 1.93° (sd 1.7°) in the IM group (p < 0.01). Blood loss was significantly less in the KA2 group compared with the IM group (784 ml (sd 357) versus 1071 ml (sd 310), p < 0.001).

Conclusion

The KneeAlign2 system provides a technically straightforward method for identifying the femoral head and performing an accurate distal femoral resection at TKA with significantly less blood loss compared with a conventional intramedullary guide. Cite this article: Bone Joint J 2017;99-B:1047–52.

Using Accelerometer-Based Portable Navigation to Perform Accurate Total Knee Arthroplasty Bone Resection in Asian Patients

Implant alignment is an important factor affecting clinical results associated with total knee arthroplasty (TKA). No report exists showing the utility of an accelerometer-based portable navigation system among patients with marked femoral bowing. The aim of this study was to evaluate the accuracy of a portable navigation system for implant alignment in Asian patients with marked femoral bowing. The authors evaluated 142 consecutive TKAs performed for primary osteoarthritis since July 2013. A portable navigation system was used in 67 knees, and a conventional jig was used in 75 knees. The authors measured the mechanical axis and femoral/tibial component alignments on long-leg radiographs obtained 2 weeks after TKA. In addition, coronal bowing of the lower limb was evaluated. The results were analyzed in the general and marked femoral bowing subgroups. There were no significant differences between the 2 groups for demographic data. The rates of femoral component outliers in the coronal plane for the navigation system and conventional technique were 1.5% and 13.3% (P=.01), respectively. Marked femoral bowing was observed in 73 knees. In the subgroup of patients with marked femoral bowing, femoral coronal alignment and its outliers were more accurate in the navigation group (0%) than in the conventional group (16.2%) (P=.025). This is the first report to show the utility of an accelerometer-based portable navigation system for accurate prosthetic alignment among Asian patients with marked femoral bowing. The navigation system decreased outliers in coronal alignment of the femur, even in cases of marked femoral bowing, but did not increase complications. [Orthopedics. 2017; 40(3):e465-e472.].

A Comparison of the Medium-Term Results of Total Knee Arthroplasty Using Computer-Assisted and Conventional Techniques to Treat Patients With Extraarticular Femoral Deformities

BACKGROUND

We compared the medium-term results of total knee arthroplasty (TKA) performed using computer-assisted surgery (CAS) and conventional techniques in patients with extraarticular femoral deformities.

METHODS

The clinical and radiographic data of 40 knees (34 patients) with extraarticular femoral deformities that underwent consecutive CAS-TKA were compared with those of a control group that underwent conventional TKA (80 knees, 63 patients). No demographic data (in particular, the causes of the extraarticular deformities) differed between the two groups. The follow-up periods of the CAS and conventional TKA groups were 6.0 and 6.3 years, respectively.

RESULTS

In the CAS group, the average knee score increased from 48.2 to 89.6 at the final follow-up (P < .001); the average function score increased from 51.4 to 91.4. The range of motion averaged 105.5° preoperatively and 123.3° postoperatively. No significant differences were found in the knee score, function score, or range of motion after TKA between the 2 groups. The average preoperative mechanical axes were 18.1° varus in both groups. The average postoperative mechanical axis was 1.4° varus in the CAS group and 3.3° varus in the conventional TKA group (P = .001). The proportion of postoperatively aligned knees was 77.5% in the CAS group and 32.5% in the conventional group (P < .001).

CONCLUSION

Although the medium-term clinical results of TKA in extraarticular femoral deformities were satisfactory in both the CAS and conventional TKA groups, the former group exhibited more accurate postoperative coronal alignment. It was useful to employ navigation in patients with extraarticular deformities of various etiologies.

Total knee arthroplasty in patients with Ranawat type-II valgus arthritic knee with a marked coronal femoral bowing deformity: comparison between computer-assisted surgery and intra-articular resection

Background

Proper limb and component alignments as well as soft tissue balance are vital for the longevity and optimal long-term outcomes of total knee arthroplasty (TKA). This procedure is technically demanding in patients with Ranawat type-II valgus arthritic knees with marked coronal femoral bowing. Computer-assisted surgery (CAS) and intra-articular bone resection with TKA are the treatments of choice for patients with ipsilateral extra-articular deformity. In theory, both CAS and intra-articular bone resection are beneficial in Ranawat type-II valgus arthritic knees with marked coronal femoral bowing deformity, but the literature on this topic is sparse. We compared the benefits of using these two techniques for TKA under this circumstance.

Methods

Patients who had Ranawat type-II valgus arthritic knees and marked coronal femoral bowing deformity and had undergone TKA at our hospital between 2005 and 2013 were enrolled in this retrospective study. Patients treated with CAS were assigned to the CAS-TKA group; patients treated with intra-articular bone resection were assigned to the Bone-Resect-TKA group. Radiographic parameters and clinical outcomes (International Knee Society (IKS) scores and patellar scores) in both groups were compared.

Results

Forty-seven patients (50 knees) met the inclusion criteria: 22 knees in the CAS-TKA group and 28 knees in the Bone-Resect-TKA group. Lateral retinaculum release was significantly (P = 0.008) higher in the Bone-Resect-TKA group. The joint-line was significantly properly restored in the CAS-TKA group (P = 0.011). The reconstructed mechanical axis was significantly (P = 0.012) closer to normal in the CAS-TKA group than in the Bone-Resect-TKA group. For component alignment, the femoral valgus and femoral flexion angles were significantly better in the CAS-TKA group (P = 0.002 and P = 0.006, respectively), but not the tibial valgus, tibial flexion, or patellar tilting angles. IKS scores and patellar scores were not significantly different between groups at a mean follow-up of 60.2 months.

Conclusions

CAS-TKA was effective for obtaining proper alignment and joint-line restoration in patients with Ranawat type-II valgus arthritic knees and marked coronal femoral bowing deformity, but not for yielding better clinical outcomes. Additional large-scale prospective randomized cohort studies with long-term follow-ups are necessary to make evidence-based recommendations.

Evaluation of lower limb axial alignment using digital radiography stitched films in pre-operative planning for total knee replacement

BACKGROUND

For patients with knee osteoarthritis, even slight anatomical variations in the femur or the tibia could affect total limb alignment during total knee replacement (TKR). Our hypothesis implies that the femoral valgus correction angle (VCA) in patients indicated for TKR, is variable and higher than the reported norm of 6° utilized in most intramedullary instrumentation systems, and that tibial bowing may result to a disparity of the tibial mechanical axis to the anatomical axis.

METHODS

Our study is a retrospective review of 216 pre-operative arthritic knees, which investigated the lower limb axial alignment using digitally-stitched films. Patients excluded from the study are those with history of previous tibial or femoral osteotomy, secondary gonarthrosis, rheumatoid arthritis, previous femoral or tibial fracture, patients for bilateral TKR, or history of hip surgery.

RESULTS

The mean age was 68-years old (range 39-86 years). The mean VCA was 7° (4.7-9.3) for men and 6.6° (4.9-9) for women. However, 71 patients (33%) had more than 7° VCA. Subsequently, 46 patients (21%) had tibial bowing producing an angle >1.5° between its mechanical and anatomic axis.

CONCLUSIONS

The 6° standard when used as a guide may result in suboptimal prosthesis positioning during conventional TKR surgery. Therefore our findings suggest that the femoral valgus correction angle has a broad range, and using standard femoral intramedullary guides should not be overlooked.

Improving outcomes in total knee arthroplasty-do navigation or customized implants have a role?

Modern total knee arthroplasty is effective at treating the pain and disability associated with osteoarthritis. The number of total knee replacements done in the USA continues to increase. Despite the great care taken during all of these procedures, some patients remain dissatisfied with their outcome. While this dissatisfaction is likely multifactorial, malalignment of the prosthetic components is a major cause of postoperative complications. A neutral mechanical axis plus or minus 3° is felt to have a positive impact on the survivorship of the prosthesis. Conventional instrumentation has been shown to have a significant number of total knee replacements that lie well outside a neutral coronal alignment. With that in mind, significant effort has been placed into the development of technology to improve the overall alignment of the prosthesis. In order to reduce the number of outliers, several companies have developed cost-effective systems to aid the surgeon in achieving a more predictably aligned prosthesis in all three planes. We will review the literature that is available regarding several of these tools to examine if navigation or custom guides improve outcomes in total knee arthroplasty. Our review supports that while both navigation and custom implants guides seem to be a cost effective way to achieve a predictable mechanical alignment of a total knee prosthesis therefore reducing the number of outliers, the cost may be increased operative times with no perceived difference in patient satisfaction with navigation custom guides.

Correcting deformity in total knee arthroplasty

Collateral ligament release is advocated in total knee arthroplasty (TKA) to deal with significant coronal plane deformities, but is also associated with significant disadvantages.

We describe steps to avoid release of the collateral (superficial medial and lateral collateral) ligaments during TKA in severely deformed knees, while correcting deformity and balancing the knee.

Cite this article: Bone Joint J 2016;98-B(1 Suppl A):101–4.

The difficult primary total knee arthroplasty: a review

Primary total knee arthroplasty (TKA) is a reliable procedure with reproducible long-term results. Nevertheless, there are conditions related to the type of patient or local conditions of the knee that can make it a difficult procedure. The most common scenarios that make it difficult are discussed in this review. These include patients with many previous operations and incisions, and those with severe coronal deformities, genu recurvatum, a stiff knee, extra-articular deformities and those who have previously undergone osteotomy around the knee and those with chronic dislocation of the patella. Each condition is analysed according to the characteristics of the patient, the pre-operative planning and the reported outcomes. When approaching the difficult primary TKA surgeons should use a systematic approach, which begins with the review of the existing literature for each specific clinical situation.

The Influence of Alignment on Midterm Outcome after Total Knee Arthroplasty in Patients With Marked Coronal Femoral Bowing

Whether the mechanical axis should be restored to neutral remains controversial when the patient has marked coronal femoral bowing. Eighty-four total knee arthroplasties were retrospectively reviewed. In the neutral-aligned group A the immediate postoperative mechanical axis of 179 ± 1° held stable (P = 0.841). The postoperative mechanical axis decreased from 176 ± 1° to 173 ± 1° (P = 0.024) in the outlier group. Progressive varus in the outlier group at follow-up was probably due implant instability and ligament imbalance as well as excessive polyethylene wear. At a mean follow-up of 75.8 months, no statistically significant difference was detected between the two groups. Long-term follow up will be needed to determine if the maintenance in radiographic results translates to better clinical outcomes.

Accuracy of CT-based patient-specific guides for total knee arthroplasty in patients with post-traumatic osteoarthritis

Published clinical trials who studied the accuracy of patient-specific guides (PSG) for total knee arthroplasty exclude patients with articular deformity of the knee joint. We prospectively analysed a series of 30 patients with post-traumatic osteoarthritis of the knee joint with use of PSG. At 1 year post-operative, the achieved biomechanical (HKA) axis and varus/valgus of the femur and tibia components were measured on anterior-posterior (AP) long-standing weight-bearing radiographs. Flexion/extension of the femoral and AP slope of the tibia component was measured on standard lateral radiographs. Percentages >3° deviation of the pre-operative planned HKA axis and individual implant components were considered as outliers. Approved and used implant size, median blood loss (ml) and operation time (min) were obtained from the operation records. Pre- and 1-year post-operative patient-reported outcome measures (PROMs) were performed. Eighty-three per cent of the patients had a HKA axis restored <3° of the pre-operative planned alignment. Varus/valgus outliers were 0.0 and 6.7 % for the femoral and tibial components, respectively. Percentages of outliers of flexion/extension were 36.7 % for the femoral component and 10.0 % for the AP slope of the tibial component. Median blood loss was 300 ml (50-700), while operation time was 67 min (44-144). In 20 % of all cases, the approved implant size was changed into one size smaller. One-year post-operative PROMs improved significantly. We conclude that the accuracy of CT-based PSG is not impaired in patients with post-traumatic osteoarthritis and this modality can restore biomechanical limb alignment.

Mini-midvastus total knee arthroplasty in patients with severe varus deformity

Patients with severe varus deformity of the knee (≥15° varus) usually are not considered good candidates for minimally invasive total knee arthroplasty (TKA). The goal of this study was to retrospectively investigate outcomes in patients with severe varus deformity after minimally invasive TKA. A study group of 52 patients with a tibiofemoral mechanical axis of 195° or greater was compared with a matched control group of 55 patients with a tibiofemoral mechanical axis of less than 195°. Clinical and radiographic evaluations according to the American Knee Society rating system were obtained preoperatively and postoperatively, and postoperative patient satisfaction in the 2 groups was compared. All patients were followed at a mean of 3 years (range, 2-5 years). Preoperatively, clinical knee and function scores and range of motion were inferior in the study group compared with the control group (P<.001). However, at the latest follow-up, both groups of patients were satisfied with the clinical results, and no significant differences were found in the knee and function scores (P>.05). Radiographic evaluation showed no differences in the mechanical axis, femoral component valgus angle, and tibial component valgus angle, and all outliers of the radiographic parameters between the 2 groups postoperatively (P >.05). The study results showed that mini-midvastus TKA did not result in more inaccurate implant positioning in patients with severe varus deformity of the knee. The clinical outcome in the group with severe varus was comparable to that in the group with less severe varus

The benefits of computer-assisted total knee arthroplasty on coronal alignment with marked femoral bowing in Asian patients

Background

Mechanical alignment guides are designed to compensate for variations in the valgus alignment angle; however, these guides may not be adequate when a patient has coronal alignment with marked bowing deformity. Previous study demonstrates better radiographic results, but the clinical benefits are a matter of speculation. The aim of this study was to investigate whether radiographic benefits of computer-assisted surgery total knee arthroplasty (CAS-TKA) would translate to clinical outcomes.

Methods

Patients with osteoarthritis and coronal alignment with marked bowing deformity who underwent total knee arthroplasty (TKA) at our institution between January 2005 and June 2012 were entered into this retrospective study. Patients were divided into three groups: patients with coronal alignment with marked bowing deformity treated with CAS-TKA; with coronal alignment with marked bowing deformity treated with conventional TKA; and without marked coronal bowing deformity treated with conventional TKA. The computer-assisted navigation and the conventional technique were then compared by radiographic parameters. The International Knee Society (IKS) scores and patellar score were obtained for all patients preoperatively and at the last follow-up visit.

Results

One hundred and thirty-seven patients (198 knees) met the inclusion criteria. For patients with osteoarthritic knees with marked femoral bowing deformity, the reconstructed mechanical axis (MA) was significantly closer to normal in the CAS-TKA group (P = 0.002) than in the conventional group. Significant differences in the reconstructed MA after conventional TKA were noted between patients without bowing and those with bowing (P = 0.003). Using the patellar score and IKS score, at a mean follow-up of 52.2 months, the differences did not achieve statistical significance among the three groups.

Conclusions

CAS-TKA was an effective alternative for obtaining proper alignment in patients with coronal alignment with marked bowing deformity. However, there was no statistically significant difference in clinical function between patients treated with CAS-TKA and conventional TKA. Long-term follow-up will be needed to determine if the improvement in radiographic results translates to better clinical outcomes.

Differences in component and limb alignment between computer-assisted and conventional surgery total knee arthroplasty

PURPOSE

Marked coronal femoral bowing may bear a risk for mal-alignment of femoral component and reconstructed mechanical axis (MA) by using conventional instrumentations. The aim of this study was to investigate the usefulness of computer-assisted surgery-total knee arthroplasty (CAS-TKA) under this circumstance.

METHODS

We retrospectively analyzed patients with osteoarthritic knee and marked coronal femoral bowing who underwent TKA at our institution. The CAS-TKA and the conventional techniques were compared by radiographic parameters in coronal and sagittal planes, and rotational alignment of femoral component was assessed by computed tomography (CT) scans. The Hospital for Special Surgery (HSS) and International Knee Society (IKS) scores were obtained for all patients preoperatively and at the last follow-up.

RESULTS

A total of 65 knees were enrolled in this study. Twenty-eight TKAs implanted using a CT-free navigation system, and the remaining 37 TKAs implanted using the conventional technique. CAS-TKAs were more consistent than conventional TKAs in aiding proper postoperative MA and ideal alignments of femoral component in the coronal and sagittal planes. However, CAS-TKA group was not obtained at significantly higher rates of femoral component in axial plane. At a mean follow-up of 43 months, there was no significant difference in HSS and IKS scores between the groups.

CONCLUSIONS

Although CAS-TKA did not have superior functional outcomes in the short-term follow-up, proper coronal and sagittal alignment of femoral component and postoperative MA were obtained in patients with marked coronal femoral bowing. The long-term follow-up will be needed to clarify the eventual benefits.

LEVEL OF EVIDENCE

Retrospective comparative study, Level III.

One-stage total knee arthroplasty with pre-existing fracture deformity: post-fracture total knee arthroplasty

The aim of the study was to assess the results of treating knee osteoarthrosis with total knee arthroplasty (TKA) after previous tibia and/or femur fractures resulting in axial limb deformities. Thirty-six knees (34 patients) were operated on. At the most recent follow-up, 4.8 years after surgery, all but one patient demonstrated an improvement in both clinical and functional KSS. This male patient required revision after 2 years. Improved range of motion was generally noted, especially extension, however, two patients with both tibia and femur fractures had worse results. TKA is an effective method of treatment for patients with arthrosis after a previous femur or tibia fractures. When deformity is severe semi-constrained or constrained, implants with extensions may be necessary.

Computer-navigated minimally invasive total knee arthroplasty for patients with retained implants in the femur

Total knee arthroplasty (TKA) in patients with knee arthritis and retained implants in the ipsilateral femur is a challenge for knee surgeons. Use of a conventional intramedullary femoral cutting guide is not practical because of the obstruction of the medullary canal by implants. Previous studies have shown that computer-assisted surgery (CAS) can help restore alignment in conventional TKA for patients with knee arthritis with retained femoral implants or extra-articular deformity, without the need for implant removal or osteotomy. However, little has been published regarding outcomes with the use of navigation in minimally invasive surgery (MIS)-TKA for patients with this complex knee arthritis. MIS has been proven to provide less postoperative pain and faster recovery than conventional TKA, but MIS-TKA in patients with retained femoral implants poses a greater risk in limb malalignment. The purpose of this study is to report the outcome of CAS-MIS-TKA in patients with knee arthritis and retained femoral implants. Between April 2006 and March 2008, eight patients with knee arthritis and retained femoral implants who underwent the CAS-MIS-TKA were retrospectively reviewed. Three of the eight patients had extra-articular deformity, including two femur bones and one tibia bone, in the preoperative examination. The anteroposterior, lateral, and long-leg weight-bearing radiographs carried out at 3-month follow-up was used to determine the mechanical axis of lower limb and the position of components. The mean preoperative femorotibial angle in patients without extra-articular deformity was 3.8° of varus and was corrected to 4.6° of valgus. With the use of navigation in MIS-TKA, the two patients in this study with extra-articular femoral deformity also obtained an ideal postoperative mechanical axis within 2° of normal alignment. Overall, there was a good restoration of postoperative mechanical alignment in all cases, with a mean angle of 0.4° of varus. No limb malalignment or component malposition was found. In clinical assessments, there were also significant improvements in knee specific scores, functional scores, and motion arc. The results of this study suggest that navigation can help achieve accurate alignment and proper prosthesis positioning in MIS-TKA for patients with retained femoral implants and for whom intramedullary rod guidance is impractical.

Total knee arthroplasty with a novel navigation system within the surgical field

Total knee arthroplasty is a common procedure, and current navigation systems are gradually gaining acceptance for improving surgical accuracy and clinical outcomes. A new navigation system used within the surgical field, iAssist, has demonstrated reproducible accuracy in component alignment. All orientation information is captured by small electronic pods and transmitted via a local wireless network, which directs the surgical workflow automatically to the femoral and tibial resection instruments. This simple and accurate navigation system used completely in the surgical field, without optical trackers or preoperative imaging, seems to be the latest generation of smart instrumentation for total knee arthroplasty.

Post traumatic knee arthritis: navigated total knee replacement without hardware removal

BACKGROUND

The Authors present the results of a series of navigated total knee replacements (TKR) without hardware removal in patients with post-traumatic arthritis following femoral fractures. The purpose of the paper was to determine the effectiveness of computer-assisted TKR in these patients compared to routine primary implants.

METHODS

Sixteen patients with post-traumatic knee arthritis following a distal femoral fracture and retained hardware were included in the study (group I). Patients in the study group were matched with patients who had undergone a computer navigated TKR using the same implant and software (group II). The indication for TKR in all group II patients was atraumatic arthritis and surgery was performed in the same period as the study group. Patients were matched for age, gender, pre-operative range of motion, severity of arthritis pre-operatively, type and grade of deformity and implant features.

RESULTS

There were no statistically significant differences in surgical time, hospital staying or intra-operative and post-operative complications between the two study groups. At the latest follow-up no statistically significant difference was seen for the Knee Society Score and WOMAC indices. Implant alignment and radiological parameters were similar in both groups.

CONCLUSIONS

This study demonstrated that post-traumatic knee arthritis following prior distal femoral fracture can be safely managed using a computer navigated TKR without hardware removal. Comparison between this patient group and a matched group with atraumatic arthritis showed similar post-operative results and complication rates.

LEVEL OF EVIDENCE

III.

Total knee arthroplasty with patient-specific instruments improves function and restores limb alignment in patients with extra-articular deformity

BACKGROUND

Restoring function and alignment when treating knee arthritis with a total knee arthroplasty (TKA) in patients who have an extra-articular deformity (EAD) from a malunion or with retained femoral hardware is a challenge. The normal anatomical landmarks are hard to find and difficult to use to obtain correct alignment. The procedure will be further challenged by angular deformity of the femur or tibia. A retrospective study was performed on a case series of patients with EAD or obliteration of the canal treated with patient-specific instruments (PSI).

METHODS

A multicenter retrospective review of 10 patients with multiplanar deformities in which the knee components were aligned with patient-specific instruments was performed. Outcome and alignment were studied.

RESULTS

At a mean follow-up of 3.4years, function improved from preoperative as evidenced by a mean increase in the KS pain score of 53 points, KS function score of 48 points and Oxford Score of 28 points (P<0.05). Flexion improved from 94° +/- 11° to 112° +/- 15° (P<0.05). Limb alignment was restored with a mean Hip-Knee-Ankle angle of 179.3° +/- 1.3° (P<0.05). Maximum outliers were 177° to 181°. An average tourniquet time of 75 +/- 9minutes (range, 62-83min) was observed.

CONCLUSIONS

The use of patient-specific instrumentation systems to perform TKA in patients without access to the intramedullary canal because of EAD or fixation devices, improved function and restored limb alignment. Mechanical alignment can easily be obtained with this technique by intra-articular correction of deformities under 20°.

LEVEL OF EVIDENCE

Level IV.

Navigation-Assisted Total Knee Arthroplasty for Osteoarthritis with Extra-Articular Femoral Deformity and/or Retained Hardware

Total knee arthroplasty (TKA) for osteoarthritis (OA) patients with extra-articular deformity is still challenging because angular deformity, canal sclerosis, or the retained hardware that precludes the use of the traditional intramedullary guide. In addition, atypical bone cut for intra-articular correction leads to imbalanced soft tissue gap. Furthermore, corrective osteotomy should be considered for severe deformity or para-articular deformity cases. Recently, navigation-assisted TKA has been reported to increase the accuracy of prosthetic positioning and limb alignment. This system can calculate mechanical axis regardless of extra-articular deformity, canal sclerosis, or retained hardware. Accordingly, navigation surgery has been considered to be a powerful option especially in TKAs with extra-articular deformity cases. Here, we report 3 successful navigation-assisted TKAs for osteoarthritis with extra-articular deformities and/or retained hardware. Navigation-assisted TKA is an effective and reliable alternative for patients with extra-articular deformities.

Surgical technique: Computer-assisted sliding medial condylar osteotomy to achieve gap balance in varus knees during TKA

BACKGROUND

Extensive posteromedial release to correct severe varus deformity during TKA may result in mediolateral or flexion instability and may require a constrained implant. We describe a technique combining computer navigation and medial condylar osteotomy in severe varus deformity to achieve a primary goal of ligament balance during TKA.

DESCRIPTION OF TECHNIQUE

The goal of this procedure was to achieve mediolateral gap balance in varus knees with rigid, recalcitrant medial contracture, with or without excessive lateral laxity, not amenable to extensive medial soft tissue releases. A sliding medial condylar osteotomy (SMCO) was performed under navigation guidance and the condylar block internally fixed using cancellous screws.

METHODS

We prospectively evaluated mediolateral laxity, Knee Society scores, and knee ROM after SMCO in 12 varus arthritic knees in 11 patients (five men, six women) undergoing TKA with a minimum followup of 2 years (mean, 2 years; range, 2-2.5 years).

RESULTS

The degree of mediolateral knee laxity improved from Grade 2 (in four knees) and Grade 3 (in eight knees) preoperatively to Grade 1 (< 5 mm) in all knees at last followup. Mean Knee Society score improved from 30 (range, 10-54) to 92 (range, 86-100). Mean knee flexion improved from 106° (range, 90°-120°) to 112° (range, 100°-124°), and no knee had any extensor lag or residual flexion deformity (> 5°). Three knees had asymptomatic fibrous union at the osteotomy site.

CONCLUSIONS

Computer-assisted SMCO in varus knees with recalcitrant medial contracture achieves improved mediolateral stability and knee function after TKA. Our technique uses navigation to accurately reposition the medial condylar block to equalize medial and lateral gaps, thereby ensuring a stable well-aligned knee without deploying constrained implants.

Intra-articular correction of extra-articular tibial deformities with total knee arthroplasty

INTRODUCTION

Extra-articular leg deformities may occur in the femur or tibia from mal-unions from previous trauma or metabolic bone disease. Secondary osteoarthritis at the knee occurs due to loss of mechanical alignment of the limb. At surgery for total knee arthroplasty, mechanical alignment can be restored intra-articularly with appropriate bone cuts and soft tissue balancing.

PRESENTATION OF CASE

We describe 2 case studies with extra-articular tibial deformities (9° and 24° varus deformity) which were corrected with a 1 stage procedure of total knee arthroplasty with intra-articular deformity correction.

DISCUSSION

Patient selection, pre-operative considerations and surgical technique are discussed with reference to the literature.

CONCLUSION

One stage intra-articular correction of extra-articular deformity is suitable for mild degrees of varus deformities (<30°). Staged corrective procedures with larger deformities in the tibia or femur can be performed with extra-articular osteotomies on top of intra-articular corrections. Consideration should be given to the use of computer navigation when conventional jigs cannot be applied to deformed bone.

Total knee arthroplasty in extra articular deformities: A series of 36 knees

BACKGROUND

The presence of extra articular deformities either in the femur or the tibia with arthritis of the knee makes total knee arthroplasty (TKA) technically demanding. The purpose of this study is to report outcomes with Total Knee Arthroplasty in patients with arthritis of the knee associated with extra articular deformity by intraarticular resection and soft tissue balancing.

MATERIALS AND METHODS

Thirty six knees (32 patients) who had arthritis of the knee associated with extra articular deformity, underwent total knee arthroplasty between 1999 and 2006 were included in this retrospective analysis. All patients had intraarticular resection with soft tissue balancing to correct the deformity. Full length weight bearing anteroposterior X-rays, Knee society scores, and Knee range of motion was recorded pre- and postoperatively.

RESULTS

The mean period of followup was 85 months (range 42-120 months). The deformities amenable to correction by intraarticular resection in our series were Femur- Coronal plane 11°-18° (mean 16.2°) Saggital plane 0°-15° (mean 10.1°) Tibia - Coronal plane 12°-24° (mean 21°). There was an improvement in the range of motion from mean of 54° preoperatively to 114° postoperatively (P value < 0.05). The Knee Society- Knee Score improved from 37 points to 85 points postoperatively (P value < 0.05). The functional score improved from a mean value of 19 to a mean of 69.5 at followup (P < 0.01). The preoperative hip knee ankle angle in the coronal plane improved from a mean of 14° ± 2° varus (26° varus to 4° valgus) to a mean of 2° ± 0.6° varus (6° varus to 2° valgus).

CONCLUSION

With a good preoperative planning and templating, intraarticular bone resection and good soft tissue balancing both in flexion and extension, correction would be possible in majority of extraarticular deformities.

The influence of preoperative deformity on valgus correction angle: an analysis of 503 total knee arthroplasties

We prospectively studied variations in valgus correction angle (VCA) and the influence of preoperative limb deformity on VCA in 503 consecutive total knee arthroplasties done in 393 patients. The percentage of limbs that had VCA values less than 5° was 10.9%, and that with VCA values greater than 7° was 44.9%. The percentage of limbs with VCA greater than 7° was significantly more in varus knees, and that with VCA less than 5° was significantly more in valgus knees; preoperative deformity showed a significant correlation with VCA. Choosing a fixed-routine VCA of 5° to 7° may cause an unacceptable planning error that may be minimized by individualizing VCA or using computer navigation.

Cadaveric results of an accelerometer based, extramedullary navigation system for the tibial resection in total knee arthroplasty

INTRODUCTION

In total knee arthroplasty, the accuracy and precision of the tibial resection must be improved. The purpose of this study was to determine the accuracy and time associated with the use of an accelerometer based, extramedullary surgical navigation system for performing the tibial resection.

MATERIALS AND METHODS

Four orthopedic surgeons performed a tibial resection utilizing the KneeAlign™ system, each on five separate, cadaveric tibiae. Each surgeon was assigned a preoperative "target" of varus/valgus alignment and posterior slope prior to each resection. The alignment of each resection was measured using both plain radiographs and computed tomography, along with the time required to use the device.

RESULTS

Regarding coronal alignment, the mean absolute difference between the preoperative "target" and tibial resection alignment was 0.77° ± 0.64° using plain radiograph, and 0.68° ± 0.46° using CT scan measurements. Regarding the posterior slope, the mean absolute difference between the preoperative "target" and the tibial resection was 1.06° ± 0.59° using plain radiograph, and 0.70° ± 0.47° using CT scan measurements. The time to use the KneeAlign™ for the fifth specimen was less than 300 s for all four orthopedic surgeons in this study.

DISCUSSION

This cadaveric study demonstrates that the KneeAlign™ system is able to accurately align the tibial resection in both the coronal and sagittal planes.

Computer-assisted total knee arthroplasty after prior femoral fracture without hardware removal

This study presents a consecutive series of patients who underwent total knee arthroplasty (TKA) after prior distal femoral fracture without hardware removal. The purpose of this study was to determine the effectiveness of computer-assisted TKA in patients with posttraumatic arthritis, specifically those with retained hardware after prior distal femoral fracture. The study group included a consecutive series of 16 patients who had developed posttraumatic knee arthritis after a distal femoral fracture with retention of hardware (group A). Patients in the study group were matched with patients who had undergone a computer-assisted TKA using the same implant and software (group B). The indication for TKA in all group B patients was atraumatic arthritis, and surgery was performed during the same period as that in the study group. Patients were matched for age, sex, preoperative range of motion, preoperative severity of arthritis, type and grade of deformity, and implant features. No statistically significant differences existed between the 2 study groups in terms of operative time, duration of hospital stay, or intra- and postoperative complications. At last follow-up, no statistically significant differences existed in Knee Society Scores and Western Ontario and McMaster Universities Arthritis Index scores. Implant alignment and radiological parameters were similar in both groups. This study demonstrated that posttraumatic knee arthritis after prior distal femoral fracture can be safely managed using a computer-assisted TKA without hardware removal. Comparison between the study group and a matched group with atraumatic arthritis showed similar postoperative results and complication rates.

Computer-assisted surgery as indication of choice: total knee arthroplasty in case of retained hardware or extra-articular deformity

PURPOSE

The use of traditional cutting guides during knee arthroplasty in some cases could be extremely difficult, if not impossible, because of angular deformities, IM sclerosis, long-stemmed hip implants, or hardware within the femoral canal that cannot be removed. In these difficult cases navigation-assisted knee arthroplasty should be considered as an effective and appealing option.

METHODS

We present 14 cases in which ideal mechanical and prosthetic alignment was achieved with different image-free, computer-assisted navigation systems, because of an extra-articular deformity (group A, nine patients) or because of a retained implant or hardware (group B, five patients).

RESULTS

After a mean follow-up of 28 months (range 12-53 months), the average knee score increased overall from a mean of 33 points (range 12-63) to 78 points (range 63-90). The average functional score improved from a mean of 32 points (range 10-65) to 72 points (range 40-90). The postoperative mechanical axis ranged between 3° of varus and 3° of valgus. There was an implant revision in one patient who had a traumatic rupture of medial collateral ligament, which occurred 27 months after the index procedure.

CONCLUSIONS

Based on our results we think that the navigation-assisted technique provides an alternative approach to the traditional instrumentation for treating these difficult patients in an effective and less invasive manner.

Computer-navigated TKA for the treatment of osteoarthritis associated with extra-articular femoral deformity

The purpose of this study was to evaluate the efficacy of computed-navigated total knee arthroplasty for the treatment of osteoarthritis associated with extra-articular femoral deformity. Between January 2008 and June 2010, twelve patients (12 knees) with osteoarthritis combing extra-articular femoral deformity underwent total knee arthroplasty using the Stryker Navigation System 3.1 (Kalamazoo, Michigan), a wireless and imageless system. Average follow-up was 12.3 ± 8.2 months (range, 3-24 months). Full-length weight-bearing anteroposterior radiographs, knee range of motion, and Knee Society Score were obtained for all patients pre- and postoperatively. The data were analyzed with SPSS version 12.0 statistical software (SPSS, Inc, Chicago, Illinois). Average preoperative overall mechanical axis of the 12 knees was -10.0° ± 4.4° of varus (range, -5° to -18.5°) and average postoperative mechanical axis was -0.9° ± 0.8° (range -2° to 0°). Average Knee Society Score increased from 40.8 ± 7.7 preoperatively to 94.9 ± 2.4 postoperatively, and average function score increased from 39.6 ± 12.3 preoperatively to 95.4 ± 4.0 postoperatively. Average knee range of motion improved from 83.7° ± 18.7° preoperatively to 115.0° ± 8.2° postoperatively. The results of the study showed that computer-navigated total knee arthroplasty may be a valuable option for patients with deformed femurs in which conventional instruments are difficult to use. Follow-up observation of the long-term therapeutic effect of computer-navigated total knee arthroplasty is still needed.

Navigation-assisted total knee arthroplasty in knees with osteoarthritis due to extra-articular deformity

PURPOSE

Extra-articular post-traumatic deformity may make difficult the implantation of total knee arthroplasty (TKA). Staged surgical procedures, including femoral or tibial osteotomy, can be required to restore proper alignment. These procedures may be inappropriate because of high rate of complications. Intra-articular resection is an alternative procedure, but it is limited by the potential compromise of collateral knee ligaments. Conventional instrumentation cannot be used in patients with previous trauma and residual bone deformity. We want to assess whether computer-assisted surgery may be a good alternative to traditional techniques.

METHODS

Twenty consecutive TKAs were performed in 20 patients (12 men and 8 women) with knee arthritis due to extra-articular deformity. The mean age was 52 years. According to Moreland method, the mean (± standard deviation) of the pre-operative hip-knee-ankle angle was 10.4° ± 8.3° in varus. In all cases, an image-free knee navigation system was used because of the severe deformity or the presence of retained hardware that prevented the use of the intramedullary rod. The average follow-up was 3.1 years.

RESULTS

One month after surgery, the mean hip-knee-ankle angle was 0.8° ± 1.2° in varus. At follow-up, the Knee Society Score increased from an average of 48 pre-operatively to 91 (P < 0.05) post-operatively, with over 90% of excellent and good results. Mean range of motion improved from a 7°-74° mean range pre-operatively to 0°-94° post-operatively.

CONCLUSIONS

The general value of navigation systems in achieving accurate bone cuts and restoring the mechanical axis has been established in the literature for standard TKA but not yet for extra-articular deformity. Our findings at mid-term follow-up on a large cohort of these patients showed that these systems used for intra-articular resection are a very effective alternative to previous techniques.

LEVEL OF EVIDENCE

Prospective study, Level IV.

Radiographic analysis of a hand-held surgical navigation system for tibial resection in total knee arthroplasty

Tibial intramedullary or extramedullary alignment guides have not been shown to be highly accurate in performing the tibial resection in total knee arthroplasty (TKA). Since May 2010, a total of 42 knees underwent a TKA using a hand-held, accelerometer-based surgical navigation system for performing the tibial resection (KneeAlign; OrthAlign Inc, Aliso Viejo, Calif). Postoperative standing anteroposterior hip-to-ankle and lateral knee-to-ankle radiographs demonstrated that 97.6% of the tibial components were placed within 90° ± 2° to the mechanical axis in the coronal plane, and 96.2% of the components were placed within 3° ± 2° to the mechanical axis in the sagittal plane. The KneeAlign greatly improves the accuracy of tibial component alignment in TKA.

Radiographic results of an accelerometer-based, handheld surgical navigation system for the tibial resection in total knee arthroplasty

In total knee arthroplasty (TKA), intramedullary and extramedullary tibial alignment guides are not proven to be highly accurate in obtaining alignment perpendicular to the mechanical axis in the coronal plane. The objective of this study was to determine the accuracy of an accelerometer-based, handheld surgical navigation system in obtaining a postoperative tibial component alignment within 2° of the intraoperative goal in both the coronal and sagittal planes. A total of 151 TKAs were performed by 2 surgeons using a handheld surgical navigation system to perform the tibial resection. Postoperatively, standing anteroposterior hip-to-ankle radiographs and lateral knee-to-ankle radiographs were performed to determine the varus/valgus alignment and the posterior slope of the tibial components relative to the mechanical axis in both the coronal and sagittal planes. Findings showed that 95.3% of the tibial components were placed within 2° of the intraoperative goal in the coronal plane and 96.1% of the components were placed within 2° of the intraoperative goal in the sagittal plane. Overall, mean postoperative lower-extremity alignment was -0.3°±2.1°, with 97% of patients having an alignment within 3° of a neutral mechanical axis. The handheld surgical navigation system improves the accuracy of the tibial resection and subsequent tibial component alignment in TKA. It is able to combine the accuracy of computer-assisted surgery systems with the ease of use and familiarity of conventional, extramedullary alignment systems, and the ability to adjust both the coronal and sagittal alignments intraoperatively may prove clinically useful in TKA.