Total knee replacement on more than 20° valgus: A case control study

Is lateral femoral condyle hypoplasia a feature of genu valgum? A morphological computed tomography study of 200 knees

BACKGROUND

Young surgeons are taught that genu valgum deformity is associated with hypoplasia of the lateral femoral condyle, despite the absence of supporting evidence. The objective of this study was to determine whether the lateral condyle was hypoplastic in genu valgum, by assessing the morphological features of the distal femur and their variations according to the severity of the coronal deformity.

HYPOTHESIS

The lateral femoral condyle is not hypoplastic in genu valgum deformity.

MATERIAL AND METHODS

The 200 included patients treated by unilateral total knee arthroplasty were divided into five groups based on their preoperative hip-knee-ankle (HKA) angle. The HKA angle, valgus cut angle (VCA), and anatomical lateral distal femoral angle (aLDFA) were measured on long-leg radiographs. Computed tomography images were then used to measure the medial and lateral anterior-posterior condylar lengths (mAPCL and lAPCL) and condylar thicknesses (mCT and lCT), distal femoral torsion (DFT), medial and lateral posterior condylar heights (mPCH and lPCH), and medial and lateral condylar volumes (mCV and lCV).

RESULTS

No significant differences were demonstrated across the five mechanical-axis groups for mAPCL, lAPCL, mCT, lCT, mPCH, or lPCH. The groups differed significantly regarding the VCA (p<0.0001), aLDFA (p<0.0001), DFT (p<0.0001), and mCV/lCV ratio (p<0.0001). VCA and aLDFA were smaller when the valgus exceeded 10°. DFT was similar in all varus knees (2.2°-2.6°) but significantly greater for knees with moderate (4.0°) or severe (6.2°) valgus. Finally, lCV was greater than mCV in valgus knees compared to varus knees.

CONCLUSION

The presence of lateral condyle hypoplasia in knees with genu valgum seems open to question. Apparent hypoplasia noted during the standard physical examination may be chiefly ascribable to distal valgus of the femoral epiphysis in the coronal plane and, with the knee flexed, to distal epiphyseal torsion, whose severity increases with the degree of valgus deformity. These considerations should be taken into account when performing distal femoral cuts for TKA, to ensure the restoration of normal anatomy in patients with genu valgus.

LEVEL OF EVIDENCE

IV.

Lateral approach total knee arthroplasty achieves equivalent patellar tracking in severe valgus deformity compared to mild valgus deformity

PURPOSE

Patellar tracking problems represent 2-10% of complications of total knee arthroplasties (TKA) in valgus knees. However, there are no studies assessing patellar tracking according to the severity of the valgus deformity. The hypothesis was that lateral approach TKA in severe valgus deformity provides equivalent patellar tracking to that in knees with mild valgus deformity.

METHODS

Between 1988 and 2016, 77 TKAs were performed via a lateral approach on a severe valgus deformity (HKA > 195°). Forty-three TKAs performed without tibial tubercle osteotomy and with complete radiological data were included in this study. These were compared with 86 matched TKAs performed via a lateral approach with a mild valgus deformity (HKA between 181° and 190°). Patellar tilt and patellar position were assessed by axial view radiographs at the last follow-up. Complications and clinical outcomes were also evaluated.

RESULTS

The follow-up was mean 52 ± 21 months in the severe valgus group. No significant differences were found between the severe valgus deformity group and the mild valgus deformity groups in patellar tilt (1.6° ± 6.6° versus 1.9° ± 3.2°, respectively) or patellar subluxation. There were complications in 12% (n = 5) and 11% (n = 9) of the severe valgus group and the mild valgus group respectively, without significant difference. There was no significant difference in extensor mechanism complication rate (2.3% versus 4.7%, respectively).

CONCLUSION

Lateral parapatellar approach, without tibial tubercle osteotomy, for TKA in severe valgus deformity results in good patellar tracking. With this approach, the extensor mechanism complication rate in severe valgus deformity was not higher than for mild valgus deformity.

LEVEL OF EVIDENCE

III.

Primary complex total knee arthroplasty with severe varus deformity and large bone defects: mid-term results of a consecutive series treated with primary implants

INTRODUCTION

In recent years, the use of constrained implants in complex primary TKA has gained popularity since these implants may better and more easily address severe instability present in complex primary cases (CPC). However, the need for a constrained TKA in CPC is controversial. We hypothesized that a standard TKA may be successful in most of CPC and that an intraoperative switching to a constrained device is rarely need even in the presence of severe instability and bone loss.

MATERIALS AND METHODS

A consecutive series of 24 CPC (28 knees) were analysed retrospectively. Inclusion criteria were a femoro-tibial angle > 12° and bone defect of grade 2-3 (group 1). Forty-eight patients (52 knees) were analysed as controls (group 2). Patients were followed up clinically and radiographically up to a minimum of 5 years.

RESULTS

In group 1, a PS was used in 24 knees and a CR in 4. In no patient, a CCK or RHK was implanted. Bone defect was treated with bone cement plus cortical screws in 15 knees (53.5%), a medial wedge in 8 (28.5%), a medial wedge plus bone grafting with cancellous screws in 5 (17.8%). Metaphyseal sleeve or cone was not used. At the last follow-up, no significant difference was found in the clinical scores between the 2 groups.

CONCLUSION

In CPC with marked varus deformity, instability and bone loss, the use of primary TKA is associated with a clinical outcome comparable to standard cases. Ligamentous balancing may be addressed using primary implants and simple cost-effective techniques may be used to manage an extensive bone loss. In most CPC, an intraoperative switching to a constrained device is not necessary.

Rotating-hinge prosthesis for aseptic revision knee arthroplasty: A multicentre retrospective study of 127 cases with a mean follow-up of five years

BACKGROUND

The use of third-generation rotating-hinge knee prostheses has increased considerably in recent years. The more anatomical design of these prostheses, together with their controlled rotation system that reduces constraints generated by the single degree of liberty, have produced better outcomes. The objective of this study was to evaluate the clinical and radiological outcomes of revision knee arthroplasty for aseptic failure using rotating-hinge prostheses.

HYPOTHESIS

The rotating-hinge knee prostheses currently used in France provide significant improvements in function and self-sufficiency of patients undergoing revision knee arthroplasty, with outcomes comparable to those reported with constrained condylar knees.

MATERIAL AND METHODS

A multicentre retrospective study was conducted in 17 centres, under the auspices of the SoFCOT. The cohort consisted of 127 patients (127 knees) operated on before 2013. The main reasons for knee revision were aseptic loosening, major instability, mechanical failure, and extensor apparatus failure. Function and self-sufficiency were assessed using the International Knee Society (IKS) score and the Devane score, respectively. Survival was defined with all-cause surgical revision as the end point.

RESULTS

Mean follow-up was 67.3±11.8 months (range, 13-180 months). Significant improvements (p<0.001) were seen in the total IKS score (+42 points), the IKS function score (+12 points), and the knee IKS score (+30 points). Paradoxically, the Devane score decreased by 0.44 point. The 5-year survival rate was 77% (95% confidence interval, 0.70-0.85). Postoperative complications developed in 29% of patients (infection, n=12; aseptic loosening, n=11; and fracture, n=7).

DISCUSSION

Rotating-hinge prostheses provide satisfactory outcomes of knee arthroplasty revision and remain an effective option for complex cases, confirming our working hypothesis. Self-sufficiency diminishes slightly. The long-term outcomes obtained using rotating-hinge prostheses are, however, less satisfactory than those observed with constrained condylar knees for aseptic TKA revision, and the complication rate is higher, although the population and local circumstances are different. Discernment is therefore in order when determining the indications of rotating-hinge prostheses.

LEVEL OF EVIDENCE

IV; retrospective cohort study.

Comparison between single- and double-bundle anterior cruciate ligament reconstructions for knee with grade 2 medial collateral ligament injury

This research discussed clinical outcomes of anterior cruciate ligament reconstruction accompanied by conservative treatment for grade 2 medial collateral ligament injury, and comparison was performed between double-bundle and single-bundle anterior cruciate ligament reconstruction.Clinical information was retrospectively collected for 41 cases suffering anterior cruciate ligament injuries accompanied by grade 2 medial collateral ligament injuries. Within 14 days after their injuries 22 cases received single-bundle anterior cruciate ligament reconstruction (SB group), while 19 were treated with double-bundle medial collateral ligament reconstruction (DB group). Physical statuses were estimated based on International Knee Documentation Committee (IKDC) and Lysholm scores, Lachman, pivot shift and manual valgus test, and range of motion (ROM), while side-to-side difference was estimated through KT 2000 arthometer.Anterior cruciate ligament reconstruction accompanied by conservative treatment showed significantly improved anteroposterior, rotational and valgus stability, and IKDC and Lysholm scores (in comparison to pre-operative status, P < .05). Incidence of pivot shift was dramatically lower in DB group (2/19) than in SB group (7/22 and 2/22; P = .028). No substantial dissimilarity existed between DB and SB groups either in Lachman and valgus tests, KT 2000, ROM, IKDC, or Lysholm scores.Anterior cruciate ligament reconstruction accompanied by conservative treatment could achieve outstanding stability and functional manifestations for cases facing anterior cruciate ligament injury accompanied by grade 2 medial collateral ligament injury. Moreover, double-bundle anterior cruciate ligament reconstruction is superior to single-bundle operation in treating rotational instability of the knee.Level of evidence: Retrospective comparative study, Level III.

Same-stage total knee arthroplasty and osteotomy for osteoarthritis with extra-articular deformity. Part II: Femoral osteotomy, prospective study of 6 cases

BACKGROUND

Same-stage (1S) total knee arthroplasty (TKA) and femoral osteotomy (FO) may deserve consideration in patients with both knee osteoarthritis and severe extra-articular knee deformity (EKD). The objective of this study was to assess clinical and radiological outcomes and morbidity (complications and revisions) in 6 patients managed with S1-TKA-FO.

HYPOTHESIS

1S-TKA-FO produces satisfactory outcomes and is not associated with higher morbidity rates compared to two-stage TKA-TO or TKA with intra-articular EKD correction, while also significantly shortening total treatment duration.

MATERIAL AND METHODS

A prospective study was performed in 6 patients managed with 1S-TKA-FO between 1999 and 2011; mean age was 64 years (range, 59-72 years) and mean body mass index was 29.5 (range, 26-35). The EKD was consistently greater than 10°. The cause was post-traumatic mal-union in 4 patients, constitutional EKD in 1 patient, and FO in 1 patient. In each patient, the clinical International Knee Society (IKS) score and the hip-knee-ankle angle (HKA), femoral mechanical angle (FMA) and tibial mechanical angle (TMA), were recorded prospectively before and after surgery.

RESULTS

A long uncemented extension stem was used in all 6 patients and a posterior-stabilised implant in 5 patients. No hinged implants were used. In 4 patients, internal fixation of the FO was performed. Mean follow-up was 10 years (range, 4-15 years). From baseline to last follow-up, the mean IKS score increased from 46 to 161 and mean flexion from 95° (range, 70-110°) to 107° (range, 90-120°). The HKA measured radiographically was between 178° and 182° in all 6 patients. The complications consisted of deep vein thrombosis in 1 patient and knee stiffness requiring manipulation under general anaesthesia in 1 patient. No patient experienced mal-union or required revision surgery.

DISCUSSION

Apart from a case-series study of 11 patients, very few data are available on 1S-TKA-FO. In our small population, no major complications were recorded. The encouraging long-term outcomes warrant a recommendation to perform 1S-TKA-FO in patients with knee osteoarthritis and an intra-femoral deformity greater than 10°.

LEVEL OF EVIDENCE

IV, prospective observational cohort study.