Increased valgus laxity in flexion with greater tibial resection depth following total knee arthroplasty

Free subchondral screws in tibial plateau fractures: do they hinder a total knee arthroplasty? Strategies to prevent complications

Open reduction and internal fixation of extended lateral column tibial plateau fractures through a tibial condyle osteotomy and limited arthrotomy with the use of free subchondral locking screws is a straightforward and safe technique. However, these free subchondral screws are enclosed in the subchondral bone and therefore virtually impossible to remove after bone healing. The question arises whether these free subchondral screws might hinder a future total knee arthroplasty. In order to refute this, we retrospectively reviewed all surgically managed tibial plateau fractures in our tertiary center during one year and assessed the number, position and configuration of these in situ subchondral screws and K-wires. In addition, we performed a cadaver study, wherein we prepared 7 tibial plateaus for a total knee arthroplasty tibial component placement with free subchondral screws in situ. In this experiment, we demonstrated that free subchondral screws do not interfere with total knee arthroplasty, but they can increase operative time in some cases. We also provide recommendations to avoid difficulties and potential complications.

At 10-Year Minimum Follow-Up, One-Third of Patients Have Patellofemoral Arthritis After Isolated Medial Patellofemoral Ligament Reconstruction Using Gracilis Tendon Autograft

PURPOSE

To report the long-term clinical outcomes after isolated medial patellofemoral ligament reconstruction (MPFLr) to treat recurrent patellar instability.

METHODS

This was a single-center study of patients undergoing an isolated MPFLr between 2000 and 2011. All patients underwent reconstruction using hamstring autograft. The inclusion criteria were a minimum 10-year follow-up period and skeletally mature patients with more than 1 episode of patellar dislocation who underwent MPFLr without an associated bony procedure.

RESULTS

A total of 54 knees were available for final analysis. The mean follow-up period was 12.3 years (range, 10-14 year). The mean age at surgery was 25 years. No patients had patellofemoral arthritis (PFA) prior to surgery. Preoperatively, the mean Caton-Deschamps index was 1.1 and the mean tibial tubercle-trochlear groove distance was 14.9 ± 2 mm (range, 7-17 mm). All patients had trochlear dysplasia according to the Dejour classification. At final follow-up, the mean Kujala score was 82.9 ± 15.3; mean International Knee Documentation Committee score, 78.3 ± 18.5; and mean Tegner score, 4.0 ± 1.7. Patients with an unsatisfactory outcome as determined by a Kujala score lower than 80 had a higher Caton-Deschamps index preoperatively and were more likely to be female patients; however, neither factor reached significance. Of the patients, 33 (66%) had no radiographic evidence of PFA whereas 15 (30%) had Iwano stage 1 and 2 had Iwano stage 2 (4%). At final follow-up, 4 patients (7.4%) had recurrent instability requiring revision surgery.

CONCLUSIONS

Isolated MPFLr with gracilis tendon autograft in appropriately selected patients is an effective long-term treatment for recurrent patellofemoral instability with low rates of recurrence. One-third of patients exhibit radiographic evidence of PFA more than 10 years after isolated MPFLr.

LEVEL OF EVIDENCE

Level IV, case series.

Functional Alignment Philosophy in Total Knee Arthroplasty – Rationale and technique for the varus morphotype using a CT based robotic platform and individualized planning

Introduction: Alignment techniques in total knee arthroplasty (TKA) continue to evolve. Functional alignment (FA) is a novel technique that utilizes robotic tools to deliver TKA with the aim of respecting individual anatomical variations. The purpose of this paper is to describe the rationale and technique of FA in the varus morphotype with the use of a robotic platform. Rationale: FA reproduces constitutional knee anatomy within quantifiable target ranges. The principles are founded on a comprehensive assessment and understanding of individual anatomical variations with the aim of delivering personalized TKA. The principles are functional pre-operative planning, reconstitution of native coronal alignment, restoration of dynamic sagittal alignment within 5° of neutral, maintenance of joint-line-obliquity and height, implant sizing to match anatomy and a joint that is balanced in flexion and extension through manipulation of implant positioning rather than soft tissue releases. Technique: An individualized plan is created from pre-operative imaging. Next, a reproducible and quantifiable method of soft tissue laxity assessment is performed in extension and flexion that accounts for individual variation in soft tissue laxity. A dynamic virtual 3D model of the joint and implant position that can be manipulated in all three planes is modified to achieve target gap measurements while maintaining the joint line phenotype and a final limb position within a defined coronal and sagittal range. Conclusion: Functional alignment is a novel knee arthroplasty technique that aims to restore constitutional bony alignment and balance the laxity of the soft tissues by placing and sizing implants in a manner that it respects the variations in individual anatomy. This paper presents the approach for the varus morphotype.

Personalized alignment in total knee arthroplasty: current concepts

Traditionally in total knee arthroplasty (TKA), a post-operative neutral alignment was the gold standard. This principle has been contested as functional outcomes were found to be inconsistent. Analysis of limb alignment in the non-osteoarthritic population reveals variations from neutral alignment and consideration of a personalized or patient-specific alignment in TKA is challenging previous concepts. The aim of this review was to clarify the variations of current personalized alignments and to report their results. Current personalized approaches of alignment reported are: kinematic, inverse kinematic, restricted kinematic, and functional. The principle of “kinematic alignment” is knee resurfacing with restitution of pre-arthritic anatomy. The aim is to resurface the femur maintaining the native femoral joint line obliquity. The flexion and extension gaps are balanced with the tibial resection. The principle of the “inverse kinematic alignment” is to resurface the tibia with similar medial and lateral bone resections in order to keep the native tibial joint line obliquity. Gap balancing is performed by adjusting the femoral resections. To avoid reproducing extreme anatomical alignments there is “restricted kinematic alignment” which is a compromise between mechanical alignment and true kinematic alignment with a defined safe zone of alignment. Finally, there is the concept of “functional alignment” which is an evolution of kinematic alignment as enabling technology has progressed. This is obtained by manipulating alignment, bone resections, soft tissue releases, and/or implant positioning with a robotic-assisted system to optimize TKA function for a patient’s specific alignment, bone morphology, and soft tissue envelope. The aim of personalizing alignment is to restore native knee kinematics and improve functional outcomes after TKA. A long-term follow-up remains crucial to assess both outcomes and implant survivorship of these current concepts.

Importance of the gender and preoperative knee sagittal alignment to avoid unnecessary tibial resection in TKR

BACKGROUND

Standard resections according to the TKR manufacturers can lead to unnecessary bone resections in some patients. The objective of this study was to determine in which patients is recommended to perform a minimal tibial resection (MTR) that could restore the joint line height (JLH).

METHODS

Navigation records of 108 consecutive posterior cruciate-substituting TKR performed by one surgeon were analyzed. Optimal tibial resection depth to restore the JLH (0 mm) was calculated by an algorithm. Postoperatively, the knees were distributed in two groups: those in which a MTR (depth ≤ 8 mm) would have been enough to restore the JLH and those in which a standard resection depth would have been necessary. ROC curves and Youden index were used to determine the cutoff point of the coronal and sagittal mechanical axis that predicted a MTR restoring the JLH. Multivariate analysis was used to identify independent factors associated with requiring an MTR.

RESULTS

A MTR could be required in 20 (18.5%) knees. In the ROC curve analyses, the cutoff points that best discriminated between minimal and standard tibial resection was  ≤ 3° of varus and  < 2° of flexion preoperative deformity. Multivariate analysis showed that female gender and preoperative flexion < 2° were significant predictors of requiring a MTR to restore JLH.

CONCLUSION

A MTR with the JLH restoration could be possible in female patients with a preoperative sagittal deformity less than 2° of flexion. Preoperative coronal alignment had no influence to discriminate when a MTR is required.