Limb alignment changes with knee flexion: A study based on CAS data

BACKGROUND

Recent evidence has questioned the value of standing limb alignment for predicting the adduction moment and forces exerted on healthy and prosthetic knees. The purpose of this study was to assess the lower limb alignment of OA knee patients at various knee flexion angles. The main hypothesis was that lower limb alignment measured throughout knee flexion does not significantly differ between patients displaying different extension alignment (neutral, varus or valgus).

METHODS

206 arthritic knee patients undergoing computer-assisted total (CAS) knee prosthesis were included. Frontal limb alignment was assessed in a systematic manner by CAS at three knee positions: extension, 90 degrees of flexion and maximal flexion. The HKA angle at each knee position and the change in HKA angle between two knee positions (delta value) were reported and compared.

RESULTS

A large proportion of OA patients had significant variation in their lower limb alignment (32% with Δ HKA > 5°). The extended limb deformity tended to reduce with knee flexion: mean of 5° and 6° deformity reduction for varus and valgus patients, 40% and 66% of varus and valgus patients progressed to neutral alignment with 90° knee flexion. Forty percent of neutral extended lower limb did not maintain their neutral alignment but rather progressed to either varus or valgus at 90° knee flexion.

CONCLUSIONS

Limb alignment in extension is a poor predictor of limb alignment in flexion in OA patients. Only considering the traditional frontal alignment of an extended lower limb for planning knee arthroplasty or osteotomy is likely insufficient.

Specific case consideration for implanting TKA with the Kinematic Alignment technique

The Kinematic Alignment (KA) technique for total knee arthroplasty (TKA) is an alternative surgical technique aiming to resurface knee articular surfaces.The restricted KA (rKA) technique for TKA applies boundaries to the KA technique in order to avoid reproducing extreme constitutional limb/knee anatomies.The vast majority of TKA cases are straightforward and can be performed with KA in a standard (unrestricted) fashion.There are some specific situations where performing KA TKA may be more challenging (complex KA TKA cases) and surgical technique adaptations should be included.To secure good clinical outcomes, complex KA TKA cases must be preoperatively recognized, and planned accordingly.The proposed classification system describes six specific issues that must be considered when aiming for a KA TKA implantation.Specific recommendations for each situation type should improve the reliability of the prosthetic implantation to the benefit of the patient.The proposed classification system could contribute to the adoption of a common language within our orthopaedic community that would ease inter-surgeon communication and could benefit the teaching of the KA technique. This proposed classification system is not exhaustive and will certainly be improved over time. Cite this article: EFORT Open Rev 2021;6:881-891. DOI: 10.1302/2058-5241.6.210042.

Calipered kinematic alignment technique for implanting a Medial Oxford®: A technical note

This note describes a surgical technique to kinematically align a medial Oxford® UKA. Applying kinematic alignment principles is an alternative, personalised, physiological, and potentially clinically advantageous method for implanting the medial Oxford® UKA. Further investigations are needed to better define the reproducibility and clinical impact of this new surgical technique.

[Alignment techniques for implantation of a total knee endoprosthesis with particular focus on kinematic alignment]

BACKGROUND

This review introduces various techniques for implantation of a total knee endoprosthesis and scrutinizes the "mechanical alignment" of a total knee endoprosthesis, whereby the various alignment concepts are examined. In particular, kinematic alignment, in terms of its significance, the individual steps of the implantation technique and the data collected, will be examined in more detail.

METHODS

Improvement in the clinical results after implantation of a total knee endoprosthesis can be achieved by a personalized, individualized, physiological implantation that respects the unique anatomical characteristics of each patient. In recent years, many alternative alignment techniques have been developed, some of them showing promising approaches.

RESULTS

The kinematic implantation technique can be performed reliably and inexpensively, and shows good biomechanical results. Although the first clinical results are encouraging, further studies should be carried out to determine the limits of optimal alignment.

Day-case surgery for total hip and knee replacement: How safe and effective is it?

Multimodal protocols for pain control, blood loss management and thromboprophylaxis have been shown to benefit patients by being more effective and as safe (fewer iatrogenic complications) as conventional protocols.Proper patient selection and education, multimodal protocols and a well-defined clinical pathway are all key for successful day-case arthroplasty.By potentially being more effective, cheaper than and as safe as inpatient arthroplasty, day-case arthroplasty might be beneficial for patients and healthcare systems. Cite this article: EFORT Open Rev 2018;3:130-135. DOI: 10.1302/2058-5241.3.170031.

Kinematic alignment technique for total hip and knee arthroplasty: The personalized implant positioning surgery

Conventional techniques for hip and knee arthroplasty have led to good long-term clinical outcomes, but complications remain despite better surgical precision and improvements in implant design and quality.

Technological improvements and a better understanding of joint kinematics have facilitated the progression to ‘personalized’ implant positioning (kinematic alignment) for total hip (THA) and knee (TKA) arthroplasty, the true value of which remains to be determined.

By achieving a true knee resurfacing, the kinematic alignment (KA) technique for TKA aims at aligning the components with the physiological kinematic axes of the knee and restoring the constitutional tibio-femoral joint line frontal and axial orientation and soft-tissue laxity.

The KA technique for THA aims at restoring the native ‘combined femoro-acetabular anteversion’ and the hip’s centre of rotation, and occasionally adjusting the cup position and design based on the assessment of the individual spine-hip relation.

The key element for optimal prosthetic joint kinematics (hip or knee) is to reproduce the femoral anatomy.

The transverse acetabular ligament (TAL) is the reference landmark to adjust the cup position.

Cite this article: EFORT Open Rev 2018;3:98-105. DOI: 10.1302/2058-5241.3.170022

[Shelf acetabuloplasty in Legg-Perthes-Calve disease]

PURPOSE OF THE STUDY

The purpose of this study was to demonstrate the contribution of shelf acetobuloplasty for the treatment of Legg-Perthes-Calve disease.

MATERIAL

Eighteen children with Legg-Perthes-Calve disease were operated on between 1992 and 2001. Mean age at diagnosis was 7 years 2 months, and mean age at surgery was 8 years 5 months (range 5-13 years). Mean motion was limited -25 degrees in abduction and internal rotation preoperatively. The radiological classification was: 2 Catterall II Herring B with signs of risk for the head, 8 IIB, 1 III C, 2 IV B, 3 IV C, and 2 at the sequelar stage. Mean excentration was 6.5 mm and mean overhang was 10.2 mm.

METHOD

The indication for surgery was aggravation of the excentration or advanced revascularization. An iliac graft was embedded in the supralimbic and covered with a rectus femoris tendon which, left continuous, provided elastic support. A bermuda cast was used in 17 cases and immediate weight-bearing in 11. The patients were hospitalized 36 hours.

RESULTS

Sixteen patients were reviewed at mean follow-up of 3 years 2 months (2 lost to follow-up). There were no complications. Clinically, the patients were pain free. Three patients had persistent limping 10 moderate limitation of motion, and three had severe stiffness. Radiologically, head covering was good in 15 cases, and joint congruency was achieved in 15 (11 of which were concentric). Shelf acetabuloplasty was considered useful in 12 cases, not useful in 1 after complete lysis of a poorly positioned graft, and of uncertain usefulness in 3 (including 2 cases treated at the sequalar stage).

DISCUSSION

Femoral osteotomy for varisation and pelvic osteotomy for reorientation or enlargement of the acetabulum are effective but have certain drawbacks (limitation of abduction, leg length discrepancy, reintervention to remove material). The excellent integration of the shelf graft at mid-term is a good sign of correct head-acetabulum adaptation, with radiological and clinical results similar to other techniques. Joint stiffness and limping are observed in very severe forms where the prognosis depends on the stage of the disease.

CONCLUSION

The patients in this series have not yet all reached maturity. Shelf plasty is a rapid, easily-performed, and safe means of enabling weight-bearing in Legg-Perthes-Calve hips undergoing excentration and beginning revascularization.