Our goal was to evaluate the use of Ponseti’s method, with minor adaptations, in the treatment of idiopathic clubfeet presenting in children between five and ten years of age. A retrospective review was performed in 36 children (55 feet) with a mean age of 7.4 years (5 to 10), supplemented by digital images and video recordings of gait. There were 19 males and 17 females. The mean follow-up was 31.5 months (24 to 40). The mean number of casts was 9.5 (6 to 11), and all children required surgery, including a percutaneous tenotomy or open tendo Achillis lengthening (49%), posterior release (34.5%), posterior medial soft-tissue release (14.5%), or soft-tissue release combined with an osteotomy (2%). The mean dorsiflexion of the ankle was 9° (0° to 15°). Forefoot alignment was neutral in 28 feet (51%) or adducted (< 10°) in 20 feet (36%), > 10° in seven feet (13%). Hindfoot alignment was neutral or mild valgus in 26 feet (47%), mild varus (< 10°) in 19 feet (35%), and varus (> 10°) in ten feet (18%). Heel–toe gait was present in 38 feet (86%), and 12 (28%) exhibited weight-bearing on the lateral border (out of a total of 44 feet with gait videos available for analysis). Overt relapse was identified in nine feet (16%, six children). The parents of 27 children (75%) were completely satisfied.

A plantigrade foot was achieved in 46 feet (84%) without an extensive soft-tissue release or bony procedure, although under-correction was common, and longer-term follow-up will be required to assess the outcome.

Cite this article: Bone Joint J 2013;95-B:1721–5.

Several emerging reports suggest an important involvement of the hindfoot alignment in the outcome of knee osteotomy. At present, studies lack a comprehensive overview. Therefore, we aimed to systematically review all biomechanical and clinical studies investigating the role of the hindfoot alignment in the setting of osteotomies around the knee. A systematic literature search was conducted on multiple databases combining “knee osteotomy” and “hindfoot/ankle alignment” search terms. Articles were screened and included according to the PRISMA guidelines. A quality assessment was conducted using the Quality Appraisal for Cadaveric Studies (QUACS) - and modified methodologic index for non-randomized studies (MINORS) scales. Three cadaveric, fourteen retrospective cohort and two case-control studies were eligible for review. Biomechanical hindfoot characteristics were positively affected (n=4), except in rigid subtalar joint (n=1) or talar tilt (n=1) deformity. Patient symptoms and/or radiographic alignment at the level of the hindfoot did also improve after knee osteotomy (n=13), except in case of a small pre-operative lateral distal tibia- and hip knee ankle (HKA) angulation or in case of a large HKA correction (>14.5°). Additionally, a pre-existent hindfoot deformity (>15.9°) was associated with undercorrection of lower limb alignment following knee osteotomy. The mean QUACS score was 61.3% (range: 46–69%) and mean MINORS score was 9.2 out of 16 (range 6–12) for non-comparative and 16.5 out of 24 (range 15–18) for comparative studies. Osteotomies performed to correct knee deformity have also an impact on biomechanical and clinical outcomes of the hindfoot. In general, these are reported to be beneficial, but several parameters were identified that are associated with newly onset – or deterioration of hindfoot symptoms following knee osteotomy. Further prospective studies are warranted to assess how diagnostic and therapeutic algorithms based on the identified criteria could be implemented to optimize the overall outcome of knee osteotomy. Remark: Aline Van Oevelen and Arne Burssens contributed equally to this work

INTRODUCTION. Medial and lateral unicompartmental knee arthroplasty (UKA) are both reliable treatment options for isolated osteoarthritis. Postoperative lower leg alignment is known to play an important role on short-term functional outcomes, which is an important argument for the use of robotic-assisted surgery. Since several anatomical and kinematic differences exist between both compartments, it seems inaccurate to aim for similar postoperative lower leg alignment in medial and lateral UKA. Purpose of this study was (I) to compare outcomes between both procedures and (II) to assess the role of preoperative and postoperative alignment on short-term outcomes in both procedures. METHODS. Patients who underwent robotic-assisted medial or lateral UKA were included if they completed functional outcomes questionnaires preoperatively and postoperatively (Western Ontario and McMaster Universities Arthritis score) and completed an artificial joint awareness questionnaire (Forgotten Joint Score) postoperatively (not used preoperatively). A total of 143 medial UKA and 36 lateral UKA patients were included and mean follow-up was 2.4-years (range: 2.0 – 5.0 year). Postoperative alignment was measured using hip-knee-ankle radiographs with a standardized method. Alignment was categorized in medial and lateral UKA as undercorrection (3° to 7° varus or valgus, respectively), neutral (−1° to 3° varus or valgus, respectively), or overcorrection (3° to 7° valgus or varus, respectively). Outcomes were compared using independent t-tests and Pearson correlation analysis was performed to assess a correlation between alignment and outcomes. RESULTS. No preoperative differences in functional outcomes were seen between medial UKA (54.9 ±14.9) and lateral UKA (50.3 ±13.4, p=0.304). Postoperatively, equivalent outcomes were noted between medial and lateral UKA in overall function (89.8 ±11.7 vs. 90.2 ±12.4, respectively, p=0.855) and joint awareness (71.2 ±24.5 vs. 70.9 ±28.2, respectively, p=0.956). Correlation analysis did not show a correlation between preoperative alignment and both functional outcomes and joint awareness for both procedures (all p > 0.4, Figure 1). More undercorrection was correlated with better functional outcomes (−0.355, p = 0.039) and less joint awareness (−0.540, p=0.005) in lateral UKA (Figure 2). In medial UKA, no correlation was noted between postoperative alignment and both functional outcomes (p=0.104) and joint awareness (p=0.069, Figure 2). With neutral postoperative alignment, less joint awareness was noted following medial UKA than lateral UKA (72.6 ±22.6 vs. 55.3 ±28.5, p=0.024). With undercorrection, however, significantly less joint awareness (85.3 ±19.5 vs. 68.2 ±26.8, p=0.024) and better functional outcomes (96.0 ±5.4 vs. 88.5 ±11.6,p=0.001) were noted following lateral UKA than medial UKA (Figure 3). CONCLUSION. At short-term follow-up, equivalent outcomes were noted between medial and lateral UKA but the optimal postoperative alignment differed between both procedures. Undercorrection (3° to 7° valgus) resulted in most optimal outcomes in lateral UKA, while this was with neutral alignment (−1° to 3° varus) in medial UKA. This study showed that postoperative alignment plays a role on short-term outcomes of UKA and suggests that precise control of postoperative alignment should be pursued, which is possible with computer navigation or robotic-assisted surgery in UKA. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Purpose: Postoperative undercorrection is recommended for unicompartmental prostheses. The long-term effects of this undercorrection on polyethylene wear and recurrent deformation have not been evaluated to date. We studied the influence of undercorrection on polyethyl-ene wear and the risk of recurrent deformation in uni-compartmental prostheses reviewed at more than 14 years (14–22 years). Material and methods: Forty unicompartmental prostheses with a polyethylene plateau without a metal back were evaluated at last follow-up. We assessed radiographs performed under fluoroscopic control to obtain a ray tangential to the polyethylene plateau. This film was used to assess penetration of the femoral component into the polyethylene. Goniometry, performed at last follow-up was compared with the postoperative goniometry to measure recurrent deformation. We retained only unicompartmental prostheses with preservation of the anterior cruciate at implantation in order to rule out possible influence of the absence of this ligament. Results: There was a significant relationship (p< 0.05) between residual postoperative varus and rate of femoral component penetration into the polyethylene. Mean polyethylene wear was 0.15 mm per year for unicompartmental prosthesis with postoperative varus greater than 10°. There was also a correlation (p< 0.01) between recurrent deformation (difference between the last follow-up and postoperative goniometry) and postoperative varus. Schematically, deformation was correlated with penetration of the femoral component into the polyethylene. Finally, recurrent deformation and rate of penetration of the femoral component into the polyethylene was greater with thinner polyethylene inserts (p< 0.05). Discussion: While undercorrection appears to be desirable for unicompartmental prostheses, it should be moderate. Excessive postoperative varus raises the risk of more rapid polyethylene wear and recurrent deformation. Furthermore, even for minimal undercorrection, the correction achieved postoperatively does not remain constant and varus defomation tends to recur. This phenomenon probably has a protective effect on the contra-lateral femorotibial compartment but in the long-term exposes to the risk of wear and recurrent deformation

Purpose of the study: The purpose of this work was to analyse the long-term results obtained with 43 medial Oxford unicompartmental prostheses implanted from 1988 to 1994 for varus deviation of the knee. Material and methods: Initially, the series included 56 patients (59 prostheses), but data were incomplete for nine patients who had died and five who were lost to follow-up. The analysis thus included 40 patients (74%): 16 were living at the time of this review (40%), 14 had died (35%) and ten had a total knee arthroplasty after failure of the Oxford prosthesis (25%). Mean age at initial surgery was 68.83±7.54 years (range 47–86). There were 13 surgical revisions: four for loosening, three for deterioration of the lateral compartment of the knee, two for repeated meniscal dislocation, two for rupture of the femoral implant and one repeated revision for impingement between the meniscal element and the femoral condyle. For ten knees, we replaced the implant with a total knee arthroplasty and in three others, we changed the meniscal piece. Results: One year after the initial operation, the overall IKS score was 189.67±14.43 points (115–200), i.e. 93% good and very good outcomes. Regarding the initial radiographic results, overall varus of the lower limb had improved from 171.31±0.46 (161–180) preoperatively to 178±3.21 (170–186) postoperatively. Sixty-three percent of the patients had normal alignment or slight undercorrection (0–4), 19% had a greater undercorrection (5–9), 2% an excessive undercorrection (10), and 16% an over correction (181–186). At review, mean follow-up was 14.8±1.16 years (13–17) and mean patient age was 82 years (n=16). The mean overall IKS was 145.52±39.90 points. Sixty-nine percent of the patients were satisfied or very satisfied with the prosthesis. The prosthesis survival was 93% at one year, 90.5% at five years, 74.7% at ten years and 70.1% at fifteen years. Discussion: Globally, the unicompartmental Oxford prosthesis has not provided in our hands the results we expected. Certain failures could undoubtedly have been avoided and should be included in the learning curve. Nevertheless, this prosthesis is certainly difficult to insert and carries a non-negligible risk of undercorrection, especially when the deviation is overcorrectible and care is taken to avoid dislocation of the meniscal element

Many authors have recommended undercorrection of the deformity when carrying out unicompartmental knee arthroplasty (UKA). The isolated effect of alignment of the knee on the outcome of UKA has, however, received little attention. We reviewed 185 UKAs at a minimum of five years after surgery. They had been carried out by a single surgeon using metal-backed tibial components in the management of arthritis of the medial compartment. We measured the tibiofemoral angle (TFA) before and at four months after operation and at the most recent assessment. The amount of correction of the TFA and any subsequent loss were recorded. While adjusting for the effects of age, weight and gender of the patients and the type and thickness of the implants, the mean correction was significantly less for those with a Marmor rating of failure (6.8°) than for those rated excellent (9.2°). The mean correction was also significantly less for patients with a Marmor rating of failure (6.8°) than for those rated poor (11.1°). The mean correction for the UKAs which were revised (6.6°) was significantly less than for those not revised (9.1°). Additionally, revised UKAs had a significantly higher percentage (63%) of thinner tibial implants (< 8 mm) than the surviving UKAs (27%). These findings suggest that undercorrection of the TFA in UKA of the medial compartment should be avoided, particularly if a thin tibial polyethylene insert is used

Purpose of the study: It is currently accepted that ligament balance should be one of the goals for total knee arthroplasty (TKA) and that this balance should be obtained by correct bone cuts or appropriate ligament procedures. There is however no standard way of assessing this balance. The purpose of this study was to define limit values for knee laxity observed in a series of normal knees and in a series of 54 TKA reviewed at more than ten years. Material and methods: Laxity in extension of normal knees was measured on forced varus and valgus films using the contralateral knees of patients who had undergone knee surgery for osteotomy or prosthesis implantation. Laxity in extension of TKA knees was measured the first postoperative year and at last follow-up by measuring the decoaptation between the tibial and femoral pieces on single-leg stance films. The change in decoaptation over time was compared with the postoperative and last follow-up goniometry figures, the IKS knee score, the number of loosenings and the number of lucent lines. Multifactorial analysis was considered significant at p< 0.05. Results: For the normal knees in extension, the medial compartment gap was 2 mm on average (range 1.5–3.5 mm) on the forced valgus images and the lateral compartment gap was 3 mm on average (range 2–4 mm) on the forced varus images. The corresponding angular value was 1° decoaptation on the forced valgus images and 1.5° on the forced varus images. Among the 54 knees with a TKA, the first postperative single-leg stance image revealed a lateral decoaptation _ 3° for 12 knees considered to present laxity, and was _ 2° for 42 knees considered not to present laxity. At last follow-up (13 years on average, range 11–14 years) the 42 knees without laxity remained unchanged without decoaptation, including the 34 normocorrected knees (±3°) and the eight undercorrected knees presenting more than 3° varus (mean undercorection 5°, range 3–7°). The 12 knees presenting postoperative radiographic decoaptation _ 3° showed at last follow-up a significant increase in laxity (p< 0.05) and 2.5° further increase in decoaptation. The increase in decoaptation occurred on normocorrected (n=7) or undercorrected (n=5) knees. This increase in decoaptation was greater with greater residual genu varum. Four groups of knees could be distinguished: normocorrected and stable; normocorrected and unstable; undercorrected and stable; overcorrected and unstable. The number of loosenings requiring revision and the number of progressive lucent lines were significantly greater among unstable knees (two loosenings, and five progressive lucent lines) than among stable knees (no loosening or lucent lines). They were also greater in the group of normocorrected and unstable knees (one loosening and two lucent lines) than in the group of undercorrected and stable knees (no loosening or lucent line). The IKS knee score of stable knees was higher than that of unstable knees irrespective of the correction (p< 0.05). Discussion: Postoperative laxity in varus with angular decoaptation greater than 3° corresponds to a lateral compartment gap and should be avoided even if the knee is properly aligned postoperatively. If the knee is stable, moderate undercorrection (3–5° varus) does not appear to have an unfavorable long-term effect on knee laxity or on the femoral and tibial pieces. Conclusion: For knees with constitutional genu varum, moderate undercorrection with a stable knee is preferable to normocorrection at the cost of lost stability

Introduction. While implant designs and surgical techniques have improved in total knee arthroplasty (TKA), approximately 20% of patients remain dissatisfied. The purpose of this study was to determine if reproduction of anatomic preoperative measurements correlated to improved clinical outcomes in TKA. Methods. We retrospectively reviewed95 patients (106 knees) who underwent a TKA between 2012 −2013 with a minimum of one year follow-up. All patients had a pre and post-operative SF-12 and WOMAC scores. Pre and 6 week post-operative radiographs were reviewed to compare restoration of coronal plane alignment, maintenance of joint line obliquity, and maintenance of tibial varus. Coronal alignment was defined as the angle formed between the mechanical axis of the femur and the the tibia. Joint line obliquity was defined as the angle between the mechanical axis of the limb and the line which best parallels the joint space at the knee. Tibial varus was compared between the preoperative proximal lateral tibial angle and the angle formed by the mechanical axis of the tibia and tibial component postoperatively. Results. In 106 patients, postoperative coronal alignment, maintenance of tibia varus, or restoration of joint line obliquity did not correlate to improved outcomes. Patients with residual varus coronal alignment of more than 2° had increased pain and total WOMAC scores (p=0.013 and p = 0.036). Patients who had under-correction of the native tibial angle, had an increase in overall WOMAC score (p=0.007) with increased pain (p=0.012), stiffness (p=0.038), and function (p = 0.001). Furthermore, over-correction of tibial angle resulted in increased WOMAC functional scores (p=0.019), but was not significant to the overall WOMAC. Conclusions. In this study, restoration of a patient's native tibial varus correlated to improved WOMAC scores at 1 year postoperatively. Undercorrection of varus resulted in worse total WOMAC scores whereas overcorrection resulted in worse WOMAC functional scores

Summary. The effect of polyethylene wear and lift-off between the tibial and femoral components on the mechanical axis was assessed in primary TKA (Total Knee Arthroplasty) based on retrieval data and full leg radiographs. Introduction. Controversy exist regarding performing a TKA with component placement in physiologic versus neutral alignment. Some literature indicates good survivorship and superior clinical outcome in undercorrected TKA's for varus osteoarthritic knees. However, other literature indicates decreased survivorship and coronal plane alignment is still one of the contributing factors to wear in total knee arthroplasty (TKA). The two determinants of the intra-articular deformity in TKA arepolyethylene wear and lift-off between the tibial and femoral compartment. The goal of this study was to evaluate the impact of wear and lift-off on the mechanical axis in neutral and varus aligned TKA's. Materials and methods. Seventy-six tibia inserts retrieved from neutral and varus aligned primary TKA's with a minimum 5 year in vivo time were assessed for the ratio of wear (RW) using a micrometer. Full-leg radiographs were assessed to determine the Hip-Knee-Ankle (HKA) and Condylar-Plateau (CP) angle, which is the intra-articular deformity. The HKA and CP angle was corrected for wear to a New-HKA angle (N-HKA) and the New-CP angle (New-CP), which was defined as lift-off. The RW and N-CP was subsequently assessed for neutral (0 ± 3°), mild varus (3 – 6°) and moderate varus (>6°) TKA's based on the mechanical axis. Results. Demographics of the study are shown in table 1. The RW correlated with frontal plane alignment, with increased wear being related to progressive varus alignment (p < 0.01). The difference from CP to N-CP and HKA to N-HKA was significant for the mild varus (p<0.01) and moderate varus (p<0.01) group. (table 2 and 3). The difference in N-CP (lift-off) among alignment groups was significant with increased lateral lift off with progressive varus alignment (p=0.02). Discussion. After correction of the intra-articular angle and the mechanical axis by the ratio of wear, coronal plane alignment significantly changed in the mild and moderate varus aligned TKA population. Both polyethylene wear and lift-off contribute to this, with progressive values in higher varus aligned TKA's. These results are important when targeting an undercorrection in TKA but should also be taken into account when describing the mechanical axis of TKA's. Conclusion. Lift-off between the tibia and femur and wear contribute significantly to the change in mechanical alignment in primary TKA's with higher values in progressive varus

We treated 63 club feet in 44 patients by a defined programme of strapping from birth followed by one of two operations performed at six weeks, either a simple calcaneal tendon lengthening or a subtalar realignment, and reviewed them prospectively. The decision as to which operation to perform was taken at four weeks after radiographic measurement of the talocalcaneal angle. All but eight patients (ten feet) were followed for a mean of 8.7 years. The overall results after calcaneal tendon lengthening were satisfactory. The re-operation rate after subtalar realignment was high (39%) due to over or undercorrection of the deformity

A technique for epiphysiodesis using a cannulated tubesaw has been developed to combine the precision of the original Phemister method with newer percutaneous methods. The approach is unilateral, and requires minimal access. Reinsertion of the removed core of bone reduces haemorrhage from the defect and augments arrest of the growth plate. In 35 patients treated by this method predicted discrepancies of 2 to 4.5 cm were reliably reduced to 0.7 ± 0.6 cm, with no serious complications. The timing of surgery is critical, and relies upon careful monitoring of the pattern of discrepancy over several years, using clinical and radiographic measurements. Undercorrection of the disparity in three patients was the direct result of late referral

Introduction. Longstanding complex muliplanar foot deformities represent a significant challenge. The traditional surgical techniques involve excessive dissection and excision of large bony wedges or modifications of the triple fusion to correct the deformity. The majority of the reports in the literature present collective data on different deformity patterns and also mix paediatric and adult patients, even with multiple correction techniques. The aim of this study was to evaluate the clinical, radiological and functional outcomes of the gradual correction of a single common deformity pattern of equino-cavo-varus using a single correction technique of the V-osteotomy and the Ilizarov frame. Material and methods. We present prospectively collected data on 40 feet in 35 adult patients with stiff longstanding equino-cavo-varus deformity. All patients had a V-osteotomy and gradual correction using an Ilizarov frame, with a mean follow-up of 20 months. We collected the American Orthopaedic Foot and Ankle Scocity score (AOFAS), the Foot and Ankle Disability Index (FADI) and a Visual Analogue Pain score (VAS) for all ptients preoperatively and between 1 and 2 years following frame removal. Results. In 33 patients (38 feet) a stable plantigrade foot was achieved with significant improvement in the gait and the foot alignment. The mean equinus, heel varus and metatarsus adductus improved significantly as measured on x-rays. The mean AOFAS score improved from 38.2 to 73.2, the mean FADI improved from 51.1 to 70.6 and the mean VAS improved from 4.5 to 0.5. Pin-site infection was encountered in 7 feet, premature consolidation in 2 feet and undercorrection in 4 feet. In 2 patients the correction had to be stopped. Conclusion. The results of this report on a single deformity pattern of equino-cavo-varus support the use of this technique for the management of these challenging cases, as a safe, versatile and powerful tool with predictable outcome

We have examined the effect of the Wagner spherical acetabular osteotomy on preserving the joint in 38 hips with a mean follow-up of 17 years. At the time of the initial operation, 55% of patients had clinical symptoms and 30 joints showed minimal or absent radiological signs of osteoarthritis. At follow-up, 54% of patients had a good functional result. The osteotomy improved the mean centre-edge angle from −3° to +15°, the mean anterior centre-edge angle to 23° and the acetabular head index to 75%. The obliquity of the acetabular roof decreased from 28° to 16°. One patient improved, but 14 deteriorated with joint degeneration. Of these, one progressed because of postoperative deep-tissue infection and five due to undercorrection. One patient needed total joint replacement after 14 years. At 17 years after operation, Wagner osteotomy had prevented progression of secondary arthritis in 63% of cases

This is a prospective gait laboratory case matched cohort study of patients after total knee arthroplasty. 20 patients who had TKA with a good functional result and a follow-up superior to 2 years were compared with 20 “normal” knees. The examiners were blinded to the group. A standardized gait analysis was performed, measuring gait kinematics, kinetics and force plate recordings using Motion Analysis computer software. All patients had a single surgeon and the same brand mobile bearing platform. The kinematics parameters were identical in both groups. However the dynamic parameters showed a statistically significant difference. At terminal swing and heel strike the operated patients had a 10-degree extension deficit in their gait analysis, despite of the fact that clinically all patients had a full extension with no quadriceps lag. The coronal plane kinetics of TKA showed valgus moment in stance despite having radiological normal (180° +/−1°) mechanical axis. (p< 0,02). In the axial plane, all operated patients had an external rotation moment greater than normals. (p< 0,01). Despite good clinical ROM and quadriceps strength, the TKA demonstrated a lack of extension in early stance. This may be due to insufficient extension gap at surgery. The valgus resultant pattern poses a more challenging question:. Are we aiming for the wrong goals in the mechanical axis, or should we consider undercorrection?. Gait analysis of the TKA patients compared to normals demonstrates dynamic differences in relation with the surgical positioning of the implant

Long term successful results of high tibial osteotomy (HTO) strongly depend on the degree of correction, and inadequate intraoperative measurements of the leg axis can lead to under or over correction, and surgeons have to solve these problems based on personal experience. This study was undertaken to investigate and compare the clinical and radiological results of navigation assisted open wedge high tibial osteotomy (HTO) versus conventional HTO at 12 months after surgery, for unicompartmental gonarthrosis. Forty navigated open HTOs with an anterior opening gap of approximately 70% of the posterior gap were included and compared with forty open HTOs performed using the conventional cable technique in terms of intraoperative leg axis assess. Navigated HTOs corrected mechanical axes to 2.9° valgus (range 0.5–6.2) with few outliers (12.5%), and maintained posterior slopes (7.9±2.3° preoperatively and 8.3±2.8° postoperatively) (P> 0.05). However, in the conventional group, only 63% of cases were within the satisfactory range (valgus 2–5°), and tendencies toward undercorrection and an increase in posterior slope were observed. Clinically both groups showed satisfactory results. Navigated HTO significantly improved the accuracy of postoperative mechanical axis and decreased correction variabilities with fewer outliers

We reviewed 34 knees in 24 children after a double-elevating osteotomy for late-presenting infantile Blount’s disease. The mean age of patients was 9.1 years (7 to 13.5). All knees were in Langenskiöld stages IV to VI. The operative technique corrected the depression of the medial joint line by an elevating osteotomy, and the remaining tibial varus and internal torsion by an osteotomy just below the apophysis. In the more recent patients (19 knees), a proximal lateral tibial epiphysiodesis was performed at the same time. The mean pre-operative angle of depression of the medial tibial plateau of 49° (40° to 60°) was corrected to a mean of 26° (20° to 30°), which was maintained at follow-up. The femoral deformity was too small to warrant femoral osteotomy in any of our patients. The mean pre-operative mechanical varus of 30.6° (14° to 66°) was corrected to 0° to 5° of mechanical valgus in 29 knees. In five knees, there was an undercorrection of 2° to 5° of mechanical varus. At follow-up a further eight knees, in which lateral epiphysiodesis was delayed beyond five months, developed recurrent tibial varus associated with fusion of the medial proximal tibial physis

Introduction:. The number of medial unicompartmental knee arthroplasties (UKA) performed over the last decade has increased by 30%, as studies have demonstrated improved knee kinematics, range of motion, and decreased perioperative morbidity versus total knee arthroplasty. However, concerns remain regarding the future risk of revision due to lateral compartment degeneration. In patients with a varus mechanical alignment and tibiofemoral subluxation secondary to medial compartment osteoarthritis, the femoral and tibial articular surfaces of the lateral compartment subsequently become incongruous, potentially increasing the focal contact stresses seen with loading. The purpose of this study is to evaluate whether the tibiofemoral congruence of the lateral compartment of the knee is improved following a medial UKA. Methods:. This study is a retrospective review of 192 consecutive medial UKAs included in an IRB-approved, single-surgeon database. All UKAs were performed using a robot-assisted surgical technique. Preoperative and postoperative standing, anteroposterior hip-to-ankle radiographs controlling for lower extremity rotation were performed from which the congruence of the lateral compartment was measured. The preoperative and postoperative degree of articular congruence (congruence index, CI) was calculated using an iterative closest point (ICP)-based software code (Matlab, MathWorks Inc., Natick, MA), specially developed to evaluate congruence of knee compartments. Following digitization of the articular surfaces of the femur and tibia, the code performs a rigid transformation that best aligns the articular surfaces and evaluates the current degree of articular congruence. A congruence index (CI) is then calculated, with a value of 1 indicating complete congruence, and a value of 0 indicating a 100% dislocation of the articular surfaces. A student's t-test was used to compare the preoperative and postoperative values of lateral compartment congruence. Results:. The mean, preoperative congruence index of the lateral compartment was 0.88 (± 0.1), which was improved to 0.93 (± 0.07), following implantation of a medial UKA (p < 0.001). Congruence of the lateral compartment was improved in 158 of the UKAs (83%), while 34 (17%) demonstrated a decrease in the congruence index postoperatively. Conclusion:. Implantation of a medial unicompartmental knee arthroplasty improves the articular surface congruence of the lateral compartment in the majority of patients with isolated, medial compartment osteoarthritis (Figure 1). We hypothesize that this factor, combined with a controlled undercorrection of the overall mechanical alignment, will improved load distribution across the lateral compartment, reduce the risk of focal contact stress points, and decrease the risk of subsequent osteoarthritic degeneration of the lateral compartment. Medial UKA not only resurfaces the medial compartment, but also may treat potential lateral compartment degeneration by improving congruence and load distribution

Introduction: One of the problems of high tibial valgus osteotomy is the loss of achieved correction, which, in turn, is associated with the deterioration of the patient’s symptoms. Aim: The aim of the present retrospective study is the correlation of certain parameters of axial alignment of the knee joint with the possibility of varus recurrence, after high tibial osteotomy, with stable fixation. Material – Method: For this purpose we studied 33 patients (37 knees), that had undergone high tibial osteotomy between 1989 and 1997. All the above patients had a follow up of at least 2 years, with a mean of 35 months. The axial parameters that were studied were the femoral condyle-femoral shaft angle, the tibial plateau-tibial shaft angle, the post operative valgus correction and the post operative medial joint space widening. Results: Loss of femorotibial angle equal to or more than 3 degrees was regarded as recurrence. This was observed in 9 knees (24%). The possibility of recurrence was strongly associated (Logistic Regression Analysis), on the one hand, with a post operative valgus correction of less than 6 degrees, and, on the other hand, with a femoral condyle-femoral shaft angle of more than 84 degrees (varus orientation of the articular surface of femoral condyles). Conclusion: It seems that both undercorrection of the femorotibial angle and varus orientation of the femoral condyles in the frontal plane do not allow the shift of the weight bearing axis of the lower extremity towards the lateral compartment and, thus, constitute risk factors for recurrence of the varus deformity

Aims: This report analyzes the inßuence of the postoperative deformity on the risk of loosening, recurrence of the deformity and progressive osteoarthritis in the remaining femoro tibial compartment. Methods: Between 1978 and 1988, 156 medial cemented uni-compartmental arthroplasties were performed in 142 patients. Alignment was measured postoperatively as the hip-knee-ankle (H.K.A.) angle on radiographs of the whole limb. Of these 156 knees, 132 retained the original implants until the patient died or until the most recent follow-up examination, eight were lost to follow-up and revision was performed in sixteen knees. 58 implants that were in patients still alive at least 10 years were evaluated clinically and for radiographic changes and limb alignment at the time of their most recent follow-up. Results: An overcorrection in valgus of the deformity (H.K.A. angle > 180 degrees) was associated with a risk of degenerative changes in the opposite compartment and revision (3 revisions among these 15 knees). Severe undercorrection in varus of the deformity (H.K.A. angle less than 170 degrees) was associated with a risk a loosening of the tibial component in the long term: (12 revisions among 50 knees). The best results were obtained in the ninety-one medial implants that were implanted in moderate varus with a postoperative H.K.A. angle of 171 to 179 degrees (one revision for loosening among these 91 implants). The varus deformity tended to recur at the latest follow-up; this change in alignment was indicative of polyethylene wear. Conclusions: Overcorrection in valgus of the preoperative deformity increased the risk of disease progression in the contralateral

This study aims to compare the gait pattern of patients operated with a TKA versus a normal population in order to evaluate if the excellent function of TKA reported in the literature corresponds to objectively measured parameters. 20 patients operated of TKA with a follow up > 1 year, all patients rated with a very good functional result (Knee Society Knee score > 85/100 – VAS < = 1/10) were compared with a group of 20 “ normal” persons. The study was blind: the examiner did not know whether the person was a normal, or which knee was operated. The test consisted in an 11 meters walk, on an AMTI force platform; the movements of the body were recorded with 6 IR cameras and analysed with the “Motion Analysis” software. The implant was a mobile bearing AP stabilised knee. The measured parameters were kinematic : speed, step length, flexion angle, duration of stance /WB phase and dynamic : flexion/extension, varus/valgus, internal/ external moments and resultant force direction. When matched with age and BMI, all kinematic parameters of the TKA group are equal to that of the normals. However, dynamic parameters differ significantly between both groups: At the end of stance phase and heel strike the operated patients have a lack of extension of 10° despite a clinical measurement of full extension (0°) In the frontal plane, all patients exhibited a valgus walking pattern but the mechanical axis measured on long standing radiographs was 180°+/−1°. In the horizontal plane, all operated patients had an external rotation of +8° compared to the normals. Despite excellent clinical scores and radiologic positioning, gait analysis demonstrates important dynamic differences between the TKA and the normal group. The extension lag at heel strike may be related to either quad weakness, or an insufficient extension gap at surgery; The valgus resultant pattern occurs despite a perfect alignment of the mechanical axis (180°) on the operated patients: this rises the question whether this alignment is the goal or if an undercorrection would be more physiologic. External rotation is superior to the normal group : it is in relation with the external rotation of the femoral and tibial components. Conclusion. Gait analysis of the TKA group of patients compared to normal demonstrates important dynamic differences in relation with the surgical positioning of the implant