Aims

This study examined windswept deformity (WSD) of the knee, comparing prevalence and contributing factors in healthy and osteoarthritic (OA) cohorts.

Aims

While mechanical alignment (MA) is the traditional technique in total knee arthroplasty (TKA), its potential for altering constitutional alignment remains poorly understood. This study aimed to quantify unintentional changes to constitutional coronal alignment and joint line obliquity (JLO) resulting from MA.

Aims. Accurate skeletal age and final adult height prediction methods in paediatric orthopaedics are crucial for determining optimal timing of growth-guiding interventions and minimizing complications in treatments of various conditions. This study aimed to evaluate the accuracy of final adult height predictions using the central peak height (CPH) method with long leg X-rays and four different multiplier tables. Methods. This study included 31 patients who underwent temporary hemiepiphysiodesis for varus or valgus deformity of the leg between 2014 and 2020. The skeletal age at surgical intervention was evaluated using the CPH method with long leg radiographs. The true final adult height (FH. TRUE. ) was determined when the growth plates were closed. The final height prediction accuracy of four different multiplier tables (1. Bayley and Pinneau; 2. Paley et al; 3. Sanders – Greulich and Pyle (SGP); and 4. Sanders – peak height velocity (PHV)) was then compared using either skeletal age or chronological age. Results. All final adult height predictions overestimated the FH. TRUE. , with the SGP multiplier table having the lowest overestimation and lowest absolute deviation when using both chronological age and skeletal age. There were no significant differences in final height prediction accuracy between using skeletal age and chronological age with PHV (p = 0.652) or SGP multiplier tables (p = 0.969). Adult height predictions with chronological age and SGP (r = 0.769; p ≤ 0.001), as well as chronological age and PHV (r = 0.822; p ≤ 0.001), showed higher correlations with FH. TRUE. than predictions with skeletal age and SGP (r = 0.657; p ≤ 0.001) or skeletal age and PHV (r = 0.707; p ≤ 0.001). Conclusion. There was no significant improvement in adult height prediction accuracy when using the CPH method compared to chronological age alone. The study concludes that there is no advantage in routinely using the CPH method for skeletal age determination over the simple use of chronological age. The findings highlight the need for more accurate methods to predict final adult height in contemporary patient populations. Cite this article: Bone Jt Open 2023;4(10):750–757

Aims

The impact of a diaphyseal femoral deformity on knee alignment varies according to its severity and localization. The aims of this study were to determine a method of assessing the impact of diaphyseal femoral deformities on knee alignment for the varus knee, and to evaluate the reliability and the reproducibility of this method in a large cohort of osteoarthritic patients.

Abstract. Introduction. Coronal plane alignment of the knee (CPAK) classification utilises the native arithmetic hip-knee alignment to calculate the constitutional limb alignment and joint line obliquity which is important in pre-operative planning. The objective of this study was to compare the accuracy and reproducibility of measuring the lower limb constitutional alignment with the traditional long leg radiographs versus computed tomography (CT) used for pre-operative planning in robotic-arm assisted TKA. Methods. Digital long leg radiographs and pre-operative CT scan plans of 42 patients (46 knees) with osteoarthritis undergoing robotic-arm assisted total knee replacement were analysed. The constitutional alignment was established by measuring the medial proximal tibial angle (mPTA), lateral distal femoral angle (LDFA), weight bearing hip knee alignment (WBHKA), arithmetic hip knee alignment (aHKA) and joint line obliquity (JLO). Furthermore, the Coronal Plane Alignment of the Knee (CPAK) classification was utilised to classify the patients based on their coronal knee alignment phenotype. Results. Mean age of the patients was 66 years (SD 9) and mean BMI 31.2 (SD 3.9). There were 27 left and 19 right sided surgeries. The Pearson's corelation coefficient was 0.722 (p=0.008) for WBHKA; 0.729 (p<0.001) for MPTA; 0.618 (p=0.14) for aHKA; 0.502 (p= 0.04) for LDFA and 0.305 (p=0.234) for JLO. CPAK classification was concordant for 53% study participants between the two groups. Conclusion. Three-dimensional CT-based modelling with computer software more accurately predicts constitutional limb alignment and JLO as defined by the CPAK classification compared to plain long-leg radiographs in pre-operative planning of total knee arthroplasty

Aims

The Coronal Plane Alignment of the Knee (CPAK) classification is a simple and comprehensive system for predicting pre-arthritic knee alignment. However, when the CPAK classification is applied in the Asian population, which is characterized by more varus and wider distribution in lower limb alignment, modifications in the boundaries of arithmetic hip-knee-ankle angle (aHKA) and joint line obliquity (JLO) should be considered. The purposes of this study were as follows: first, to propose a modified CPAK classification based on the actual joint line obliquity (aJLO) and wider range of aHKA in the Asian population; second, to test this classification in a cohort of Asians with healthy knees; third, to propose individualized alignment targets for different CPAK types in kinematically aligned (KA) total knee arthroplasty (TKA).

Aims

Varus-valgus constrained (VVC) devices are typically used in revision settings, often with stems to mitigate the risk of aseptic loosening. However, in at least one system, the VVC insert is compatible with the primary posterior-stabilized (PS) femoral component, which may be an option in complex primary situations. We sought to determine the implant survivorship, radiological and clinical outcomes, and complications when this VVC insert was coupled with a PS femur without stems in complex primary total knee arthroplasties (TKAs).

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Alternative alignment concepts, including kinematic and restricted kinematic, have been introduced to help improve clinical outcomes following total knee arthroplasty (TKA). The purpose of this study was to evaluate the clinical results, along with patient satisfaction, following TKA using the concept of restricted kinematic alignment.

Aims

Once knee arthritis and deformity have occurred, it is currently not known how to determine a patient’s constitutional (pre-arthritic) limb alignment. The purpose of this study was to describe and validate the arithmetic hip-knee-ankle (aHKA) algorithm as a straightforward method for preoperative planning and intraoperative restoration of the constitutional limb alignment in total knee arthroplasty (TKA).

Aims

A comprehensive classification for coronal lower limb alignment with predictive capabilities for knee balance would be beneficial in total knee arthroplasty (TKA). This paper describes the Coronal Plane Alignment of the Knee (CPAK) classification and examines its utility in preoperative soft tissue balance prediction, comparing kinematic alignment (KA) to mechanical alignment (MA).

Aims

Patients with a deformity of the hindfoot present a particular challenge when performing total knee arthroplasty (TKA). The literature contains little information about the relationship between TKA and hindfoot alignment. This systematic review aimed to determine from both clinical and radiological studies whether TKA would alter a preoperative hindfoot deformity and whether the outcome of TKA is affected by the presence of a postoperative hindfoot deformity.

Aims. An algorithm to determine the constitutional alignment of the lower limb once arthritic deformity has occurred would be of value when undertaking kinematically aligned total knee arthroplasty (TKA). The purpose of this study was to determine if the arithmetic hip-knee-ankle angle (aHKA) algorithm could estimate the constitutional alignment of the lower limb following development of significant arthritis. Methods. A matched-pairs radiological study was undertaken comparing the aHKA of an osteoarthritic knee (aHKA-OA) with the mechanical HKA of the contralateral normal knee (mHKA-N). Patients with Grade 3 or 4 Kellgren-Lawrence tibiofemoral osteoarthritis in an arthritic knee undergoing TKA and Grade 0 or 1 osteoarthritis in the contralateral normal knee were included. The aHKA algorithm subtracts the lateral distal femoral angle (LDFA) from the medial proximal tibial angle (MPTA) measured on standing long leg radiographs. The primary outcome was the mean of the paired differences in the aHKA-OA and mHKA-N. Secondary outcomes included comparison of sex-based differences and capacity of the aHKA to determine the constitutional alignment based on degree of deformity. Results. A total of 51 radiographs met the inclusion criteria. There was no significant difference between aHKA-OA and mHKA-N, with a mean angular difference of −0.4° (95% SE −0.8° to 0.1°; p = 0.16). There was no significant sex-based difference when comparing aHKA-OA and mHKA-N (mean difference 0.8°; p = 0.11). Knees with deformities of more than 8° had a greater mean difference between aHKA-OA and mHKA-N (1.3°) than those with lesser deformities (-0.1°; p = 0.009). Conclusion. This study supports the arithmetic HKA algorithm for prediction of the constitutional alignment once arthritis has developed. The algorithm has similar accuracy between sexes and greater accuracy with lesser degrees of deformity. Cite this article: Bone Joint Open 2020;1-7:339–345

In the vast majority of patients, the anatomical and mechanical axes of the tibia in the coronal plane are widely accepted to be equivalent. This philosophy guides the design and placement of orthopaedic implants within the tibia and in both the knee and ankle joints. However, the presence of coronal tibial bowing may result in a difference between these two axes and hence cause suboptimal placement of implanted prostheses. Although the prevalence of tibial bowing in adults has been reported in Asian populations, to date no exploration of this phenomenon in a Western population has been conducted. The aim of this study was to quantify the prevalence of coronal tibial bowing in a Western population. This was an observational retrospective cohort study using anteroposterior long leg radiographs collected prior to total knee arthroplasty in our high volume arthroplasty unit. Radiographs were reviewed using a Picture Archiving and Communication System. Using a technique previously described in the literature for assessment of tibial bowing, two lines were drawn, each one third of the length of the tibia. The first line was drawn between the tibial spines and the centre of the proximal third of the tibial medullary canal. The second was drawn from the midpoint of the talar dome to the centre of the distal third of the tibial medullary canal. The angle subtended by these two lines was used to determine the presence of bowing. Bowing was deemed significant if more than two degrees. The position of the apex of the bow determined whether it was medial or lateral. Measurements were conducted by a single observer and 10% of measurements were repeated by the same observer and also by two separate observers to allow calculation of intraclass correlation coefficients (ICCs). A total of 975 radiographs consecutively performed in the calendar years 2015–16 were reviewed, 485 of the left leg and 490 of the right. In total 399 (40.9%) tibiae were deemed to have bowing more than two degrees. 232 (23.8%) tibiae were bowed medially and 167 (17.1%) were bowed laterally. The mean bowing angle was 3.51° (s.d. 1.24°) medially and 3.52° (s.d. 1.33°) laterally. Twenty-three patients in each group (9.9% medial/13.7% lateral) were bowed more than five degrees. The distribution of bowing angles followed a normal distribution, with the maximal angle observed 10.45° medially and 9.74° laterally. An intraobserver ICC of 0.97 and a mean interobserver ICC of 0.77 were calculated, indicating excellent reliability. This is the first study reporting the prevalence of tibial bowing in a Western population. In a significant proportion of our sample, there was divergence between the anatomical and mechanical axes of the tibia. This finding has implications for both the design and implantation of orthopaedic prostheses, particularly in total knee arthroplasty. Further research is necessary to investigate whether prosthetic implantation based on the mechanical axis in bowed tibias results in suboptimal implant placement and adverse clinical outcomes

Aims. The aim of this study was to examine whether hips with unilateral osteoarthritis (OA) secondary to developmental dysplasia of the hip (DDH) have significant asymmetry in femoral length, and to determine potential related factors. Patients and Methods. We enrolled 90 patients (82 female, eight male) with DDH showing unilateral OA changes, and 43 healthy volunteers (26 female, 17 male) as controls. The mean age was 61.8 years (39 to 93) for the DDH groups, and 71.2 years (57 to 84) for the control group. Using a CT-based coordinate measurement system, we evaluated the following vertical distances: top of the greater trochanter to the knee centre (femoral length GT), most medial prominence of the lesser trochanter to the knee centre (femoral length LT), and top of the greater trochanter to the medial prominence of the lesser trochanter (intertrochanteric distance), along with assessments of femoral neck anteversion and neck shaft angle. Results. The percentages of hips with an absolute difference of > 5 mm in femoral GT and LT lengths were significantly larger in the DDH group (24% for both) compared with those of the control group (2% and 7%, respectively). The femoral length GT of the affected femur was significantly shorter in Crowe I and longer in Crowe IV than that of the unaffected side. The affected-to-unaffected difference of the intertrochanteric distance showed positive correlation with that of the femoral length GT in Crowe I and Crowe II/III, and negative correlation with that of the femoral length LT in the Crowe I and Crowe IV groups. Conclusion. Hips with unilateral end-stage OA secondary to DDH show significant asymmetry in femoral length between both the greater and lesser trochanter and the knee compared with controls. The intertrochanteric distance was a morphological factor related to femoral-length asymmetry. When undertaking total hip arthroplasty (THA) in the presence of DDH, long leg radiographs or CT measurements should be used to assess true leg-length discrepancy. Cite this article: Bone Joint J 2019;101-B:297–302

Aims

The management of a significant bony defect following excision of a diaphyseal atrophic femoral nonunion remains a challenge. We present the outcomes using a combined technique of acute femoral shortening, stabilized with a long retrograde intramedullary nail, accompanied by bifocal osteotomy compression and distraction osteogenesis with a temporary monolateral fixator.

The mucopolysaccharidoses (MPS) are a group of inherited lysosomal storage disorders with clinical manifestations relevant to the orthopaedic surgeon. Our aim was to review the recent advances in their management and the implications for surgical practice.

The current literature about MPSs is summarised, emphasising orthopaedic complications and their management.

Recent advances in the diagnosis and management of MPSs include the recognition of slowly progressive, late presenting subtypes, developments in life-prolonging systemic treatment and potentially new indications for surgical treatment. The outcomes of surgery in these patients are not yet validated and some procedures have a high rate of complications which differ from those in patients who do not have a MPS.

The diagnosis of a MPS should be considered in adolescents or young adults with a previously unrecognised dysplasia of the hip. Surgeons treating patients with a MPS should report their experience and studies should include the assessment of function and quality of life to guide treatment.

Cite this article: Bone Joint J 2017;99-B:1132–9

Background. Temporary hemiepiphysiodesis using 8 plate guided growth has gained widespread acceptance for the treatment of paediatric angular deformities. This study aims to look at outcomes of coronal lower limb deformities corrected using temporary hemiepiphysiodesis over an extended period of follow up. Methods. A retrospective analysis was undertaken of 56 children (92 legs) with coronal plane deformities around the knee which were treated with an extraperiosteal 2 holed titanium plate and screws between 2007 and 2015. Pre and post-op long leg radiographs and clinic letters were reviewed. Results. The mean age was 11.9 years (range 3 to 16) with a mean angular deformity of 12.3 degrees (5.1 to 33.5). The mean rate of correction was 0.8 degrees per month. Isolated distal femur correction occurred at a mean rate of 0.6 degrees per month (0.2 to 1.4) and isolated tibia at a rate of 0.5 degrees per month (0.0 to 1.7). Children treated with concurrent treatment of both femur and tibia corrected at a rate of 1.4 degrees per month (0.1 to 2.7). Similar rates of correction occur in children aged 10 and over compared to those younger than 10 (0.8 degrees per month compared to 0.7). We also saw similar rates of correction with extended follow up. The average rate of correction over the first 9 months post op was 0.8 degrees compared to 0.6 degrees over the following 10 months. Conclusion. This study is the largest long term follow up of 8 plate hemiepiphysiodesis which highlights the rate of correction in all age groups. Implications. With this knowledge surgeons can make a more informed decision regarding placement of hemiepiphysiodesis plates and length of time required for correction of angular deformities. It may also lead to consideration of alternative, more powerful techniques if the rate of correction is insufficient. Conflict of Interest: None declared

Aims. The aim of this study was to compare the post-operative radiographic and clinical outcomes between kinematically and mechanically aligned total knee arthroplasties (TKAs). . Patients and Methods. A total of 60 TKAs (30 kinematically and 30 mechanically aligned) were performed in 60 patients with varus osteoarthritis of the knee using a navigation system. The angles of orientation of the joint line in relation to the floor, the conventional and true mechanical axis (tMA) (the line from the centre of the hip to the lowest point of the calcaneus) were compared, one year post-operatively, on single-leg and double-leg standing long leg radiographs between the groups. The range of movement and 2011 Knee Society Scores were also compared between the groups at that time. Results. The angles of orientation of the joint line in the kinematic group changed from slight varus on double-leg standing to slight valgus with single-leg standing. The mechanical axes in the kinematic group passed through a neutral position of the knee in the true condition when the calcaneus was considered. The post-operative angles of flexion and functional activity scores were significantly better in the kinematic than in the mechanical group (p < 0.003 and 0.03, respectively). Conclusion. A kinematically aligned TKA results in a joint line which has a more parallel orientation in relation to the floor during single- and double-leg standing, and more neutral weight-bearing in tMA than a mechanically aligned TKA. Cite this article: Bone Joint J 2017;99-B:640–6

Background. Post-operative (postop) lower limb alignment in unicompartmental knee arthroplasty (UKA) has been reported to be an important factor for postop outcomes. Slight under-correction of limb alignment has been recommended to yield a better clinical outcomes than neutral alignment. It is useful if the postop limb alignment can be predicted during surgery, however, little is known about the surgical factors affecting the postop limb alignment in UKA. The purpose of this study was to examine the influence of the medial tibial joint line elevation on postop limb alignment in UKA. Methods. Seventy-four consecutive medial UKAs were enrolled in this study. All the patients received a conventional fixed bearing UKA. Pre-operative (preop) and postop limb alignment was examined using long leg radiograph and lower limb alignment changes were calculated. Femoral and tibial osteotomy thickness were measured during surgery. Medial tibial joint line change was defined as polyethylene thickness minus tibial osteotomy thickness and sawblade thickness (1.27mm). Positive values indicated a tibial joint line elevation. Medial femoral joint line change was defined as femoral distal component thickness (6.5mm) minus femoral distal osteotomy thickness and sawblade thickness. Positive values indicated a femoral joint line reduction. Medial joint distraction width was also calculated by tibial joint line elevation plus femoral joint line reduction. The correlation of lower limb alignment change with polyethylene insert thickness, the medial tibial joint line elevation, femoral joint line reduction, or joint distraction width were analyzed. Results. The mean preop hip-knee-ankle (HKA) angle was 7.1 ± 3.3° in varus and postop was 2.1 ± 3.0° in varus. The mean lower limb alignment change was 5.0 ± 2.6°. The mean polyethylene insert thickness was 8.5 ± 0.8mm, the tibial joint line elevation was 4.4 ± 1.3mm and the medial femoral joint line reduction was 0.0 ± 1.1mm, the joint distraction width was 4.5 ± 1.5mm. The polyethylene insert thickness, the medial tibial joint line elevation, and the joint distraction width were positively correlated with the lower limb alignment change (R=0.27; P<0.05, R=0.47; P<0.001, R=0.53; P<0.001, respectively) (Figure 1a,b,d). There was no correlation between the medial femoral joint line reduction and the lower limb alignment change (Figure 1c). Discussion. The postop limb alignment in total knee arthroplasty (TKA) is determined by the osteotomy angle of the femur and tibia. On the other hand, it has been reported that the postop alignment in UKA is not influenced by the osteotomy angle but by the insert thickness. Our results indicated that the medial tibial joint line elevation and the joint distraction width were more useful to predict lower limb alignment change than the insert thickness itself. Measuring the medial tibial osteotomy thickness during surgery will help surgeon to predict postop lower limb alignment in UKA. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

Purpose. Recently, kinematic aligned total knee arthroplasty (TKA) has gained interest for achieving better clinical outcomes over mechanical aligned TKA. The primary goal of kinematic aligned TKA is to position the femoral and tibial components so that the angles and levels of the distal and posterior femoral joint lines and the tibial joint line are each restored to the patient's natural alignment, and not to a neutral limb alignment that is unnatural for most patients. Despite good clinical outcomes reported at short to mid-term follow-up, surgeons should know reasons why this method is useful and safe surgery and carefully assess the long-term outcomes until this new technique is settled as standardized procedure for TKA. The main purpose of the present study was to compare postoperative radiography and clinical scores following kinematic and mechanical aligned TKA. Methods. Sixty TKAs—30 kinematic and 30 mechanical aligned—were performed in patients with varus-type osteoarthritis using a navigation system. Using postoperative double-leg and single-leg standing long leg radiographs, joint line orientation angle to the floor, conventional mechanical axis (cMA), and true mechanical axis (tMA; line from hip center to the lowest point of calcaneus) were compared between the two groups. One-year after surgeries, range of motion and the patient-derived score of the 2011 Knee Society Score (2011 KSS), which includes four categories: symptoms, patient satisfaction, patient expectations, and functional activities, e.g., walking/standing, standard activities, advanced activities, and discretionary activities, were compared between the two groups. Results. Joint line orientation angles were 1.3 ±1.8 ° varus in the kinematic and 3.2 ± 2.7° valgus in the mechanical group with double-leg standing condition (p<0.05), which were shifted to 0.7 ± 1.7° valgus and 4.3 ± 1.9° valgus with single-leg standing condition, respectively. In double-leg standing condition, cMAs passed through 43.8 ± 10.2 % in the kinematic and 48.7 ± 7.6 % in the mechanical group (p<0.05), which were shifted to 49.2 ± 12.2 % and 53.7 ± 7.5 % in tMA assessment, respectively. Postoperative flexion angle was significantly better in kinematic aligned TKA compared with mechanical aligned TKA (121.7±9.1 vs. 117.3±14.8, p<0.05). Among 4 contents of 2011 KSS, only functional activity score showed better results in the kinematic group compared with the mechanical group (p<0.05). Conclusions. Kinematic aligned TKA exhibited parallel joint line to the floor during single and double-leg standing and neutral weight-bearing in tMA when compared with mechanical aligned TKA, which might result in better functional score