Extra-articular deformity may be present in patients requiring TKA. Underlying causes include trauma, metabolic bone disease, congenital deformity, or prior osteotomy. Patients with intra-articular deformity have a combination of intra-articular bone loss and concomitant ligament contraction which can be managed in the standard fashion. In these cases establishing appropriate limb alignment and management of bone loss coincide well with the standard ligament balancing employed to provide a stable knee. However, if extra-articular deformity is not corrected extra-articularly, it must be corrected by a compensatory distal femoral or proximal tibial resection to reproduce appropriate limb alignment. Complex instabilities may result from this type of wedge resection because it occurs between the proximal and distal attachments of the collateral ligaments and so produces asymmetrical ligament length alterations. Femoral compensatory wedge resection for extra-articular deformity produces extension instability without affecting the flexion gap and so femoral deformities are POTENTIALLY more difficult to correct than tibial deformities where the compensatory tibial cut influences flexion AND extension equally. Lack of access to the intramedullary canal (as well as increased complexity of producing appropriately placed bone cuts) may be managed with computer guidance or patient specific instruments. The closer a deformity is to the knee, the greater its importance and the effect on the surgical correction. This is a directly proportional relationship, so that as the apex of the deformity moves from juxta-articular to more distant, the amount of corrective wedge needed to re-align the limb decreases proportionally. Rotatory deformities most commonly effect extensor mechanism tracking. The effect is similar to any other deformity in that proximity to the knee and increases the likelihood that it will have a significant local effect. In general, these deformities may be clinically, and radiographically more subtle and so must be searched for. They should be managed by restoring normal rotational parameters of the bone or by appropriate compensation of component rotation relative to the bone. As the need for prosthetic constraint increases due to ligament imbalance or deficiency, intramedullary stems may be required. Their use may be compromised by the presence of the deformity. The younger the patient and the more severe the deformity the more likely I am to treat the deformity by correction at the site of the deformity rather than compensating with abnormal bone resections. The older the patient and the milder the deformity (or the amount of correction required) the more intra-articular correction +/− increased TKA constraint is feasible

Extra-articular deformity may be present in patients requiring TKA. Underlying causes include trauma, metabolic bone disease, congenital deformity, or prior osteotomy. Patients with intra-articular deformity can have a combination of intra-articular bone loss and concomitant ligament contraction which can be managed in the standard fashion. In these cases establishing appropriate limb alignment and management of bone loss coincide well with the standard ligament balancing employed to provide a stable knee. However, if extra-articular deformity is not corrected extra-articularly, it must be corrected by a compensatory distal femoral or proximal tibial resection to reproduce appropriate limb alignment. Complex instabilities may result from this type of wedge resection because it occurs between the proximal and distal attachments of the collateral ligaments and so produces asymmetrical ligament length alterations. Femoral compensatory wedge resection for extra-articular deformity produces extension instability without affecting the flexion gap and so femoral deformities are POTENTIALLY more difficult to correct than tibial deformities where the compensatory tibial cut influences flexion AND extension equally. Lack of access to the intramedullary canal (as well as increased complexity of producing appropriately placed bone cuts) may be managed with computer guidance or patient specific instruments. The closer a deformity is to the knee, the greater its importance and the effect on the surgical correction. This is a directly proportional relationship, so that as the apex of the deformity moves from juxta-articular to more distant, the amount of corrective wedge needed to re-align the limb decreases proportionally. Rotatory deformities are complex and most commonly effect extensor mechanism tracking. In general the effect is similar to any other deformity in that proximity to the knee increases the likelihood that it will have a significant local effect. In general, these deformities are clinically, and radiographically more subtle and so must be searched for. They should be managed by an attempt to restore normal rotational parameters of the bone itself or appropriate compensation of component rotation in relation to the bone. As prosthetic constraint increases one may need to use intramedullary stems. Their use may be compromised by the deformity. Finally, the younger the patient and the more severe the deformity the more likely I am to treat the deformity by correction at the site of the deformity rather than compensating with abnormal bone resections. The older the patient and the milder the deformity (or the amount of wedge correction required) the more likely I am to manage the deformity with intra-articular correction and increased TKA constraint

Introduction. Restoration of mechanical axis is one of the main aims during Total Knee Arthroplasty (TKA) surgery. Treatment of osteoarthritis (OA) of the knee with extra-articular deformity either in femur or in tibia poses a technical challenge in achieving this aim. Insufficient correction of axis is associated with poor clinical outcome of total knee arthroplasty (TKA). Extra-articular deformity can either be addressed with compensatory intra-articular bone resection at the time of TKA or correctional osteotomy prior to or at the time of TKA. Patients & Methods & Results. We present our experience of treating 7 patients with knee arthritis (9 knees) and significant extra-articular deformity. Two patients had OA knee with severe valgus deformity in tibia from recurrent stress fractures. One was treated with one-stage corrective osteotomy and long stem modular TKA. The other had deformity correction with two level tibial osteotomy with intramedullary nail and modular long stem TKA later. Both required tibial tubercle osteotomy during TKA. Two patients with bilateral OA knees and significant varus deformity had sequential deformity correction with Taylor Spatial Frame (TSF) followed by TKA on one side and a single stage intra-articular correction during TKA on the other. Three patients with knee OA and associated deformity (femoral - two pt., tibia one pt.) had symptom resolution with just correction of malaligment with Taylor Spatial Frame (TSF) and did not require TKA. Conclusion. Complex extra-articular femoral or tibial deformities may require proper limb realignment prior to TKA. Our series supports all three approaches to correcting significant extra-articular deformity with knee OA. Each case should be considered individually and planned accordingly

Introduction. Arthritic knees requiring total knee replacement may present with additional deformities located along the femur or tibia away from the articular region. These deformities may be congenital, developmental, associated with metabolic bone disease, or acquired as a result of malunited fractures or previous advocated for arthritic knee with ipsilateral extra-articular deformity. Methods. We undertook retrospective study to evaluate the results of total knee arthroplasty in arthritic knee with extra-articular deformity in 26 knees (24 patients). Sixteen deformities were in tibia and ten deformities were in femur. All patients underwent total knee arthroplasty with intraarticular bone resection and soft tissue balancing. Results. Average period of follow up was 30 months. Average preoperative arc of motion was 57.5 degrees, which improved to 102.5 degrees. The average preoperative knee society knee score 23.5 points, which improved to an average of 91.3 points at the time of last follow up. The average functional score was 27.0 points, which improved to average of 88.0 points. There were no complications such as infection, ligament instability or component loosening. Conclusion. Intra-articular bone resection is an effective procedure for management of arthritic knees with extra-articular deformity

Deformity can be associated with significant bone loss, ligament laxity, soft-tissue contractures, distortion of long bone morphology, and extra-articular deformity. Correction of varus, valgus, or flexion deformity requires soft tissue releases in conjunction with bone cuts perpendicular to the long axes of the femur and tibia. Cruciate-retaining or -substituting implants can be used based on surgeon preference if the ligaments are well balanced. However, in presence of severe deformity, additional measures may be warranted to achieve alignment and balance. TKA then becomes a more challenging proposition and may require the surgeon to perform extensive releases, adjunct osteotomies and deploy more constrained implants. Merely enhancing constraint in the implant, however, without attending to releases and extra-articular correction may not suffice. Pre-operative planning, i.e., whether intra-articular correction alone will suffice or extra-articular correction is required, will be highlighted. Surgical principles and methods of performing large releases, reduction osteotomy, lateral epicondylar sliding osteotomy, sliding medial condylar osteotomy, and closed wedge diaphyseal/metaphyseal osteotomy concomitantly with TKA will be illustrated with examples. Results of a large series of TKA with extra-articular deformity resulting from coronal bowing of femoral or tibial diaphysis, malunited fractures, prior osteotomies, and stress fractures will be presented. The techniques reported can successfully restore alignment, pain-free motion, and stability without necessarily using more constrained implants

The treatment of patients with osteoarthritis of the knee and associated extra-articular deformity of the leg is challenging. Current teaching recognises two possible approaches: (1) a total knee replacement (TKR) with intra-articular bone resections to correct the malalignment or (2) an extra-articular osteotomy to correct the malalignment together with a TKR (either simultaneously or staged). However, a number of these patients only have unicompartmental knee osteoarthritis and, in the absence of an extra-articular deformity would be ideal candidates for joint preserving surgery such as unicompartmental knee replacement (UKR) given its superior functional outcome and lower cost relative to a TKR [1). We report four cases of medial unicondylar knee replacement, with a simultaneous extra-articular osteotomy to correct deformity, using novel 3D printed patient-specific guides (Embody, UK) (see Figure 1). The procedure was successful in all four patients, and there were no complications. A mean increase in the Oxford knee score of 9.5, and in the EQ5D VAS of 15 was observed. To our knowledge this is the first report of combined osteotomy and unicompartmental knee replacement for the treatment of extra-articular deformity and knee osteoarthritis. This technically challenging procedure is made possible by a novel 3D printed patient-specific guide which controls osteotomy position, degree of deformity correction (multi-plane if required), and orientates the saw-cuts for the unicompartmental prosthesis according to the corrected leg alignment. Using 3D printed surgical guides to perform operations not previously possible represents a paradigm shift in knee surgery. We suggest that this joint preserving approach should be considered the preferred treatment option for suitable patients

Aims. The aims of this retrospective study were to determine the incidence of extra-articular deformities (EADs), and determine their effect on postoperative alignment in knees undergoing mobile-bearing, medial unicompartmental knee arthroplasty (UKA). Patients and Methods. Limb mechanical alignment (hip-knee-ankle angle), coronal bowing of the femoral shaft and proximal tibia vara or medial proximal tibial angle (MPTA) were measured on standing, full-length hip-to-ankle radiographs of 162 patients who underwent 200 mobile-bearing, medial UKAs. Results. Incidence of EAD was 7.5% for coronal femoral bowing of >5°, 67% for proximal tibia vara of >3° (MPTA<87°) and 24.5% for proximal tibia vara of >6° (MPTA<84°). Mean postoperative HKA angle achieved in knees with femoral bowing ≤5° was significantly greater when compared to knees with femoral bowing >5° (p=0.04); in knees with proximal tibia vara ≤3° was significantly greater when compared to knees with proximal tibia vara >3° (p=0.0001) and when compared to knees with proximal tibia vara >6° (p=0.0001). Conclusion. Extra-articular deformities are frequently seen in patients undergoing mobile-bearing medial UKAs, especially in knees with varus deformity>10°. Presence of an EAD significantly affects postoperative mechanical limb alignment achieved when compared to limbs without EAD and may increase the risk of limbs being placed in varus>3° postoperatively. Clinical Relevance. Since the presence of an EAD, especially in knees with varus deformity>10°, may increase the risk of limbs being placed in varus>3° postoperatively and may affect long-term clinical and implant survival outcomes, UKR in such knees should be performed with caution

There is enough evidence to show that navigation improves precision of component placement and consistent and accurate restoration of limb alignment, allowing the surgeon to achieve the desired neutral or kinematic alignment. Computer-assisted TKA provides excellent information regarding gap equality and symmetry throughout the knee range of motion. Accurate soft-tissue balancing is facilitated by CAS. It allows precise, quantitative soft tissue release for deformities, especially in knees with severe flexion contractures and severe rigid varus and valgus deformities. It allows accurate restoration of joint line, and posterior femoral offset. Knee arthritis with complex extra-articular deformities and in-situ hardware can be tackled appropriately using computer navigation where conventional techniques may be inadequate. It also allows intra-articular correction for extra-articular deformities due to malunions and facilitates extra-articular correction in cases with severe extra-articular tibial deformities. In obese patients, where the alignment of the limb is difficult to assess, computer navigation improves accuracy and reduces the number of outliers. The ability to quantify the precise amount of bone cuts and soft tissue releases needed to equalise gaps and restore alignment, reduced blood loss, and reduced incidence of systemic emboli improves the safety of the procedure and hastens functional recovery of the patient. Recent evidence shows that the rate of revision especially in younger patients is reduced with navigation

Limb deformity is common in patients presenting for knee arthroplasty, either related to asymmetrical wear patterns from the underlying arthritic process (intra-articular malalignment) or less often major extra-articular deformity due to prior fracture malunion, childhood physical injury, old osteotomy, or developmental or metabolic disorders such as Blount's disease or hypophosphatemic rickets. Angular deformity that is above the epicondyles or below the fibular neck may not be easily correctable by adjusted bone cuts as the amount of bone resection may make soft tissue balancing impossible or may disrupt completely the collateral ligament attachments. Development of a treatment plan begins with careful assessment of the malalignment which may be mainly coronal, sagittal, rotational or some combination. Translation can also complicate the reconstruction as this has effects directly on location of the mechanical axis. Most intra-articular deformities are due to the arthritic process alone, but may occasionally be the result of intra-articular fracture, periarticular osteotomy or from prior revision surgery effects. While intra-articular deformity can almost always be managed with adjusted bone cuts it is important to have available revision type implants to enhance fixation (stems) or increase constraint when ligament balancing or ligament laxity is a problem. Extra-articular deformities may be correctable with adjusted bone cuts and altered implant positioning when the deformity is smaller, or located a longer distance from the joint. The effect of a deformity is proportional to its distance from the joint. The closer the deformity is to the joint, the greater the impact the same degree angular deformity will have. In general deformities in the plane of knee are better tolerated than sagittal plane (varus/valgus) deformity. Careful pre-operative planning is required for cases with significant extra-articular deformity with a focus on location and plane of the apex of the deformity, identification of the mechanical axis location relative to the deformed limb, distance of the deformity from the joint, and determination of the intra-articular effect on bone cuts and implant position absent osteotomy. In the course of pre-operative planning, osteotomy is suggested when there is inability to correct the mechanical axis to neutral without excessive bone cuts which compromise ligament or patellar tendon attachment sites, or alternatively when adequate adjustment of cuts will likely lead to excessive joint line obliquity which can compromise ability to balance the soft tissues. When chosen, adjunctive osteotomy can be done in one-stage at the time of TKA or the procedures can be done separately in two stages. When simultaneous with TKA, osteotomy fixation options include long stems added to the femoral (or tibial) component for intramedullary fixation, adjunctive plate and screw fixation, and antegrade (usually locked) nailing for some femoral osteotomies. Choice of fixation method is often influenced by specific deformity size location, bone quality and amount, and surgeon preference. Surgical navigation, or intra-operative x-ray imaging methods (or both) have both been used to facilitate accurate correction of deformity in these complex cases. When faced with major deformity of the femur or tibia, with careful planning combined osteotomy and TKA can result in excellent outcomes and durable implant fixation with less constraint, less bone loss, and better joint kinematics than is possible with modified TKA alone

Varus deformity encompasses a wide spectrum of pathology and merits individualised treatment. In most knees there is loss of articular cartilage or bone medially; this is associated with contractures of posteromedial structures of varying rigidity. In addition, there may be significant elongation of lateral ligamentous structures, and associated extra-articular femoral or tibial bowing or angulation. The principles of correction of varus include (i) a thorough clinical and radiological assessment of the limb before surgery and examination under anesthesia, (ii) appropriate bone cuts to correctly orient prostheses and restore normal alignment of the limb, (iii) equalising medial and lateral balance in flexion and extension by soft tissue releases and concomitant bony procedures and (iv) addressing associated bony defects and extra-articular deformity. Examples of each of these situations will be shown along with the technique deployed. Results of conventional TKA in treating 173 knees with varus deformity exceeding 20o will be presented. Our technique of selective posteromedial release, reduction osteotomy of posteromedial tibial flare, sliding medial condylar osteotomy and bone grafting of medial defects, with preservation of medial collateral ligament integrity will be shown. The method of correcting extra-articular deformity will be depicted. With these techniques, mean tibiofemoral angle of 22.7 degrees varus pre-operatively (range 15–62) was corrected to 5.3 degrees valgus (range 2–9) post-operatively. 86% knees were in 4–10 degrees valgus post-operatively. Recent experience with CAS in treating over 200 patients with deformity exceeding 20 degrees will be presented along with the risk factors leading to malalignment. Correction of severe varus deformity by the techniques reported can successfully restore alignment, painfree motion, and stability without the use of highly constrained implants

Computer navigation has been advocated as a means to improve limb and component alignment and reduce the number of outliers after total knee arthroplasty (TKA). We aimed to determine the alignment outcomes of 1500 consecutive computer-assisted TKAs performed by a single surgeon, using the same implant, with a minimum 1 year follow-up, and to analyze the outliers. Based on radiographic analysis, 112 limbs (7.5%) in 109 patients with mechanical axis malalignment of > 3° were identified and analyzed. The indication for TKA was osteoarthritis in 107 patients and rheumatoid arthritis in 2 patients. Fifty-eight patients (53%) had undergone simultaneous bilateral TKA and 13 patients (12%) had a BMI >30. Preoperative varus deformity was seen in 100 limbs and valgus deformity in 12 limbs. Thirty limbs (27%) had an extra-articular deformity (2 post HTO limbs, 3 malunited fractures, 1 stress fracture, 21 severe femoral bowing and 3 tibial bowing) and 21 limbs (19%) had severe lateral laxity or subluxation. Thirty-eight limbs (34%) had a preoperative deformity of =10° and 24 limbs (21.5%) had varus or valgus deformity of >20°. Postoperatively, 11 limbs were malaligned at ±3°, 74 limbs at ±4°, 22 limbs at ±5°, 2 limbs at ±6°, and 2 limbs at ±7°. Coronal plane malalignment of > ±3° of the femoral component was seen in 28 limbs, tibial component in 32 limbs, and both femoral and tibial components in 13 limbs. Twenty-six limbs with preoperative varus deformity had a postoperative valgus alignment of >183° and 3 limbs with valgus deformity had a postoperative varus alignment of <177°. The incidence of outliers for postoperative limb alignment was low at 7.5% with the tibial component showing a higher incidence of coronal malalignment. Malalignment may be more common in cases of simultaneous bilateral procedures, preoperative limb alignment of =10°, limbs with extra-articular deformities and severe lateral instability. There was a tendency towards over-correction of the hip-knee-ankle axis in both varus- and valgus-deformed knees. Further detailed statistical analysis of the data will be presented. This is the largest single-surgeon series of consecutive navigated TKAs and consequently the largest analysis of outliers that highlights which knees are likely to fall outside the +3 degrees of acceptable alignment and which therefore behoove the surgeon to exercise greater caution

The extent of soft-tissue release and the exact structures that need to be released to correct deformity and balance the knee has been a controversial subject in primary total knee arthroplasty. Asian patients often present late and consequently may have profound deformities due to significant bone loss and contractures on the concave side, and stretching of the collateral ligament on the convex side. Extra-articular deformities may aggravate the situation further and make correction of these deformities and restoration of ‘balance’ more arduous. These considerations do not apply if a hinged prosthesis is used, as may be warranted in an elderly, low-demand patient. However, in active, younger patients, it may be best to avoid use of excess constraint by balancing the soft-tissues and using the least constrained implant. Releasing collateral ligaments during TKA has unintended consequences such as the creation of significant mediolateral instability and a flexion gap which exceeds the extension gap; both of these may require a constrained prosthesis to achieve stability. We will show that soft-tissue balance can be achieved even in cases of severe varus, valgus, flexion and hyperextension deformities without collateral ligament release. The steps are: 1) Determining pre-operatively whether deformity is predominantly intra-articular or extra-articular, 2) Individualizing the valgus resection angle and bony resection depth, 3) Meticulous removal of osteophytes, 4) Reduction osteotomy, posteromedial capsule resection, sliding medial or lateral condylar osteotomy, extra-articular corrective osteotomy, 5) Compensating for bone loss, 6)Only rarely deploying a more constrained device. Case examples will be presented to illustrate the entire spectrum of varus deformities

Soft-tissue release plays an integral part in primary total knee arthroplasty by ‘balancing’ the knee. Asian patients often present late and consequently may have large deformities due to significant bone loss and contractures medially, and stretching of the lateral collateral ligament. Extra-articular deformities may aggravate the situation further and make correction of these deformities more arduous. Several techniques have been described for correction of deformity by soft-tissue releases. However, releasing the collateral ligament during TKA has unintended consequences such as the creation of significant mediolateral instability and a flexion gap which exceeds the extension gap; both of these may require a constrained prosthesis to achieve stability. We will show that soft-tissue balance can be achieved even in cases of severe varus deformity without performing a superficial medial collateral ligament release. The steps are: Determining pre-operatively whether deformity is predominantly intra-articular or extra-articular; Individualizing the valgus resection angle and bony resection depth; Reduction osteotomy, posteromedial capsule resection, sliding medial condylar osteotomy, extra-articular corrective osteotomy; Compensating for bone loss; Only rarely deploying a more constrained device. Case examples will be presented to illustrate the entire spectrum of varus deformities

Soft-tissue release plays an integral part in primary total knee arthroplasty by ‘balancing’ the knee. Asian patients often present late and consequently may have large deformities due to significant bone loss and contractures medially, and stretching of the lateral collateral ligament. Extra-articular deformities may aggravate the situation further and make correction of these deformities more arduous. Several techniques have been described for correction of deformity by soft-tissue releases. However, releasing the collateral ligament during TKA has unintended consequences such as the creation of significant mediolateral instability and a flexion gap which exceeds the extension gap; both of these may require a constrained prosthesis to achieve stability. We will show that soft-tissue balance can be achieved even in cases of severe varus deformity without performing a superficial medial collateral ligament release. The steps are: 1. Determining preoperatively whether deformity is predominantly intra-articular or extra-articular; 2. Individualizing the valgus resection angle and bony resection depth; 3. Reduction osteotomy, posteromedial capsule resection, sliding medial condylar osteotomy, extra-articular corrective osteotomy; 4. Compensating for bone loss; 5. Only rarely deploying a more constrained device. Case examples will be presented to illustrate the entire spectrum of varus deformities

Management of a knee with valgus deformities has always been considered a major challenge. Total knee arthroplasty requires not only correction of this deformity but also meticulous soft tissue balancing and achievement of a balanced rectangular gap. Bony deformities such as hypoplastic lateral condyle, tibial bone loss, and malaligned/malpositioned patella also need to be addressed. In addition, external rotation of the tibia and adaptive metaphyseal remodeling offers a challenge in obtaining the correct rotational alignment of the components. Various techniques for soft tissue balancing have been described in the literature and use of different implant options reported. These options include use of cruciate retaining, sacrificing, substituting and constrained implants. Purpose. This presentation describes options to correct a severe valgus deformity (severe being defined as a femorotibial angle of greater than 15 degrees) and their long term results. Methods. 34 women (50 knees) and 19 men (28 knees) aged 39 to 84 (mean 74) years with severe valgus knees underwent primary TKA by a senior surgeon. A valgus knee was defined as one having a preoperative valgus alignment greater than 15 degrees on a standing anteroposterior radiograph. The authors recommend a medial approach to correct the deformity, a minimal medial release and a distal femoral valgus resection of angle of 3 degrees. We recommend a sequential release of the lateral structures starting anteriorly from the attachment of ITB to the Gerdy's tubercle and going all the way back to the posterolaetral corner and capsule. Correctability of the deformity is checked sequentially after each release. After adequate posterolateral release, if the tibial tubercle could be rotated past the mid-coronal plate medially in both flexion and extension, it indicated appropriate soft tissue release and balance. Fine tuning in terms of final piecrusting of the ITB and or popliteus was carried out after using the trial components. Valgus secondary to an extra-articular deformity was treated using the criteria of Wen et al. In our study the majority of severe valgus knees (86%) could be treated by using unconstrained (CR, PS) knee options reserving the constrained knee / rotating hinge options only in cases of posterolateral instability secondary to an inadequate large release or in situations with very lax or incompetent MCL. Results. The average follow up was 10 years (range 8 to 14 years). The average HSS knee scores improved from 48 points preoperatively (range 32 to 68 points) to 91 points (range 78 to 95 points) postoperatively. The average postoperative range of motion measured with a goniometer was 110 degrees (range 80 to 135 degrees) which was a significant improvement over the preoperative levels (average 65 degrees). None of the patients were clinically unstable in the medioloateral or anteroposterior plane at the time of final follow up. The average preoperative valgus tibiofemoral alignment was 19.6 degrees (range 15 degrees to 45 degrees). Postoperatively the average tibio-femoral alignment was 5 degrees (range 2 degrees to 7 degrees) of valgus. No patient in the study was revised. Conclusion. Adequate lateral soft tissue release is the key to successful TKA in valgus knees. The choice of implant depends on the severity of the valgus deformity and the extent of soft tissue release needed to obtain a stable knee with balanced flexion and extension gaps. The most minimal constraint needed to achieve stability and balance was used in this study. In our experience the long term results of TKR on severe valgus deformities using minimal constrained knee have been good

Deformity can be associated with significant bone loss, ligament laxity, soft-tissue contractures, distortion of long bone morphology, and extra-articular deformity. Correction of varus, valgus, or flexion deformity requires soft tissue releases in conjunction with bone cuts perpendicular to the long axes of the femur and tibia. Cruciate-retaining or -substituting implants can be used based on surgeon preference if the ligaments are well balanced. However, in presence of severe deformity, additional measures may be warranted to achieve alignment and balance. TKA then becomes a more challenging proposition and may require the surgeon to perform extensive releases, adjunct osteotomies and deploy more constrained implants. Merely enhancing constraint in the implant however without attending to releases and extra-articular correction may not suffice. Certain myths in deformity correction will be presented. Technical tips with regard to preoperative planning, i.e., whether intra-articular correction alone will suffice or extra-articular correction is required, will be highlighted. Surgical principles and methods of performing large releases, reduction osteotomy, lateral epicondylar sliding osteotomy, sliding medial condylar osteotomy, and closed wedge diaphyseal/metaphyseal osteotomy concomitantly with TKA will be illustrated with examples. Technique of performing TKA with concomitant extra-articular deformity resulting from coronal bowing of femoral or tibial diaphysis, malunited fractures, prior osteotomies, and stress fractures will be presented. The techniques reported can successfully restore alignment, pain-free motion, and stability without necessarily using more constrained implants

Deformity can be associated with significant bone loss, ligament laxity, soft-tissue contractures, distortion of long bone morphology, and extra-articular deformity. Correction of varus, valgus, or flexion deformity requires soft tissue releases in conjunction with bone cuts perpendicular to the long axes of the femur and tibia. Cruciate-retaining or -substituting implants can be used based on surgeon preference if the ligaments are well balanced. However, in presence of severe deformity, additional measures may be warranted to achieve alignment and balance. TKA then becomes a more challenging proposition and may require the surgeon to perform extensive releases, adjunct osteotomies and deploy more constrained implants. Merely enhancing constraint in the implant however without attending to releases and extra-articular correction may not suffice. Preoperative planning, i.e., whether intra-articular correction alone will suffice or extra-articular correction is required, will be highlighted. Surgical principles and methods of performing large releases, reduction osteotomy, lateral epicondylar sliding osteotomy, sliding medial condylar osteotomy, and closed wedge diaphyseal/metaphyseal osteotomy concomitantly with TKA will be illustrated with examples. Results of a large series of TKA with extra-articular deformity resulting from coronal bowing of femoral or tibial diaphysis, malunited fractures, prior osteotomies, and stress fractures will be presented. The techniques reported can successfully restore alignment, pain free motion, and stability without necessarily using more constrained implants

Some DEFINITIONS are necessary: “STEMS” refers to “intramedullary stem extensions”, which may be of a variety of lengths and diameters, fixed with cement, porous coating or press fit alone and which may be modular or an inherent part of the prosthesis. The standard extension keel on the tibia does not qualify as a “stem (extension)”. COMPLEX implies multiple variables acting on the end result of the arthroplasty with the capability of inducing failure, as well as necessary variations to the standard surgical technique. A lesser degree of predictability is implied. More specifically, the elements usually found in an arthritic knee and used for the arthroplasty are missing, so that cases of COMPLEX primary TKA include: Soft tissue coverage-(not relevant here), Extensor mechanism deficiency-patellectomy, Severe deformity, Extra-articular deformity, Instability: Varus valgus, Instability: Plane of motion, Instability: Old PCL rupture, Dislocated patella, Stiffness, Medical conditions: Neuromuscular disorder, Ipsilateral arthroplasty, Prior incisions, Fixation hardware, Osteopenia, Ipsilateral hip arthrodesis, Ipsilateral below knee amputation, etc. Complexity includes MORE than large deformity, i.e., success with large deformity does NOT mean success with constrained implants regardless of indication. In addition, the degree of constraint must be specified to be meaningful. NECESSARY presumably this means: “necessary to ensure durable fixation in the face of poor bone quality or more mechanically constrained” and SUFFICIENT suggests that stems, by themselves or in some shape of form, by themselves “will ensure success (specifically here) of fixation”. If we can start with the second proposal, that STEMS are SUFFICIENT for success the answer is: “NO”, many more aspects of surgical technique and implant design are required. Even if all other aspects of the technique are exemplary, some types of stems or techniques are inadequate, e.g., completely uncemented, short stem extensions. The answer to the first proposal is: “YES, in many cases”. The problem will be to determine which cases. There are philosophical analogies to this question that we already know the answer to. ANALOGY: Is a life-raft necessary on a boat? Yes, you may not use it, but it is considered necessary. Is a life-raft “sufficient” on a boat? No, other problems may occur. Are seat belts necessary? Are child seats necessary? The AAOS already has a position on child restraints, an analogous situation, where a party who cannot control their situation (anesthetised patient/ child) functions in the care of a responsible party. The objection may be argued in terms of cost saving by NOT using increased fixation. A useful analogy, (that would of course require specific analysis), is that of patellar resurfacing: universal resurfacing is cost-effective when considering the expense of even a small number of secondary resurfacings. Of course a complex arthroplasty that requires a revision procedure is far more expensive than secondary patellar resurfacing and so universal use of the enhanced fixation in the face of increased constraint makes sense. The human cost of revision surgery tips the balance irrefutably. DANGER-We must avoid the glib conclusion, often based on poor quality data, that constrained implants do not need additional intramedullary fixation (with stem extensions). When “complexity” is involved, complex analysis is appropriate to select the best course

There is ample data to confirm that Computer-assisted total knee replacement improves alignment of the limb when compared with the conventional technique. There is also published evidence that optimum alignment correlates with longevity of implants. CAS enables accurate component alignment of both femoral and tibial components. It enables accurate restoration of the posterior tibial slope which has important consequences for flexion range and stability of the component in flexion especially if mobile bearing implants are considered. CAS also aids in correctly orienting rotation of the femoral component; this has value in minimizing patellar maltracking. We will present our data showing accurate restoration of joint line and posterior femoral offset. As CAS ensures alignment, rotation, sizing and positioning of components, the surgeon is free to devote his efforts to ensuring soft-tissue balance and stability, since TKA is really a ‘soft-tissue’ operation. How CAS is of immense value in deformity correction and soft-tissue balancing will be illustrated with examples. It helps in better understanding and quantification of the effects of soft-tissue release on flexion-extension gaps and this is of great value not only for minimal deformities (to minimise releases) but also for severe deformities (to ensure complete correction by adequate release). CAS is invaluable in helping equalize flexion-extension gaps; how it can help balance the flexion gap to the extension gap by ‘virtual surgery’ will be depicted with examples. It is particularly useful in presence of hardware in the femur or tibia and for concomitant extra-articular deformity. We have also found a consistent improvement in recovery of functional milestones with CAS with similar results for both unilateral and bilateral TKAs. Furthermore, there is evidence to support that ensuring alignment has important benefits in improving functional and quality of life scores. In addition, those with alignment of mechanical axis within 3 degrees of normal have been shown to have a shorter stay in hospital by 2 days. Studies have shown reduced blood loss and incidence of emboli after CAS TKA. Using CAS routinely for all cases, the author is ‘time neutral’. While there is always room for improvement with evolving technologies and CAS is no exception, it already has enormous benefits in the performance and outcome of TKA, and is an important part of the surgical armamentarium for a successful knee arthroplasty

Introduction. There is a controversy with regard to the treatment of osteoarthritis (OA) of the knee in patients with considerable deformities of the femoral or tibial shafts. Some surgeons prefer to correct the deformity while performing TKA at the level of the knee joint. However, this technique requires accurate planning and execution of the planned cuts. In addition, the use of intramedullary guides in such cases may not be possible or desirable and may lead to complications. There is a strong indication for using navigation in such cases. Methods. The navigation technique was used in both laboratory and clinical setting, First, we compared between navigational and conventional techniques in performing TKA in 24 plastic knee specimens (Sawbones, Sweden) that have osteoarthritic changes and complex tibial or femoral deformities. A demo kit for conventional instrumentation of posterior stabilised TKA (Scorpio, Stryker) was used for 12 cases and an image-free navigation system (Stryker) was used for a corresponding 12 cases. There were 4 different deformities; severe mid-shaft tibial varus, severe distal third femoral valgus, complex deformity distal femur and deformity following a revision TKA. The surgical procedures were performed by 3 arthroplasty surgeons, each surgeon operated on 8 knee specimens (4 knees in each arm of the study with 4 different deformities). Deformities were corrected at the level of the knee joint during TKA without prior osteotomies. For conventional techniques, surgeons used a combination of both intramedullary and extramedullary guides. Postoperative long leg radiographs were used to assess coronal alignment. Second, we used the same navigational technique clinically to perform TKA in patients with extra-articular deformities. Results. Using both navigational and conventional techniques, it was possible to indirectly correct shaft deformities by adjusting the inclination of bone cuts at the level of the knee joint. The amount of bone cutting at distal femur and proximal tibia were variable depending on the location and direction of the deformity. There was no compromise of collateral ligaments or patellar tendons in both techniques. However, the accuracy of restoring normal alignment was better in navigational techniques. The results of the clinical cases are still in progress waiting analysis of a longer term follow up. Discussion. Navigational techniques eliminated the use of both intramedullary and extramedullary guides. The improved accuracy with navigational techniques led to better alignment that can improve functional and survival outcome of similar cases of TKA in real patients