A majority of patients present with varus alignment and predominantly medial compartment disease. The secret of success in osteoarthritis (OA) treatment is patient selection and patient specific treatment. Different wear patterns have been described and that knowledge should be utilised in modern knee surgery. In case of isolated anteromedial OA, unicompartmental knee arthroplasty (UKA) should be one of the therapeutic options available to the knee surgeon.

The discussion not to offer a UKA to patients is based on the fear of the surgeon not being able to identify the right patient and not being able to perform the surgery accurately. The common modes of failure for UKA, which are dislocation or overcorrection leading to disease progression, can be avoided with a fixed bearing implant. Wear can probably be avoided with newer polyethylenes and avoidance of overstuffing in flexion of the knee. Revision for unexplained pain and unknown causes should disappear once surgeons understand persistent pain after surgery much better than they do today.

The choice in favor of UKA is a choice of function over survivorship, a choice for reduced comorbidity and lower mortality. Many of the common problems in TKA are not an issue in UKA. Component overhang, decreased posterior offset, changed joint line height, gap mismatch, flexion gap instability, lift off and paradoxical motion hardly exist in UKA if the replacement is performed according to resurfacing principles with respect for the native knee anatomy.

New technologies like navigation, PSI and robotics will help with alignment and component positioning. Surgeon education and training should allow over time UKA to be performed by all of us.

One of the arguments in favor of unicompartmental knee arthroplasty (UKA) is the possibility of an easier revision. Especially if UKA is considered as an early intervention allowing bridging until total knee arthroplasty (TKA) is necessary at later age. If indeed primary TKA results can be obtained at time of revision, UKA becomes a real indication to postpone TKA until a later age.

For obtaining primary TKA results, a primary knee should be indicated for the revision. This is possible if the UKA cuts were conservative and within the resection level of a primary TKA. Furthermore bone loss should be contained and either be resected or easily solved with substituting techniques compatible with a primary TKA. Finally, the primary implant utilised should allow a full interchangeability of the tibial and femoral sizes. This allows a lower tibial cut during the revision, often leading to a smaller size but interchangeability avoids downsizing the femur and creating flexion gap instability.

If the UKA to TKA revision asks for stems, bone substitutions, joint line changes and more constraint, the primary result will not be obtained.

Therefore it is important to select a bone preserving UKA system that allows for conservative bone cuts and avoids deep keel preparations.

UKA to TKA with primary components and without gap mismatches or joint line changes leads to excellent outcome.

Introduction

Patellofemoral arthroplasty (PFA) can give excellent results in well-selected patients. Axial alignment has been extensively studied in this type of surgery. However because there is no distal femoral cut, coronal alignment in PFA is less well known. The position of the patellofemoral component decides the varus or valgus alignment of the implant.

Introduction

Patient satisfaction after total hip arthroplasty (THA) has been reported to be significantly better than after total knee arthroplasty (TKA). The same has been observed for the capacity to forget during daily life activities about the operated joint. Recently a new patient reported outcome score, the Forgotten Joint Score (FJS-12) a twelve item questionaire, has been used to evaluate postoperative outcome in joint arthroplasty. A better FJS-12 score was measured in THA than in TKA objectivating the intuitive feeling that the joint was more forgotten in THA than in TKA.

Total knee arthroplasty (TKA) is a major orthopaedic intervention. The length of a patient's stay has been progressively reduced with the introduction of enhanced recovery protocols: day-case surgery has become the ultimate challenge.

This narrative review shows the potential limitations of day-case TKA. These constraints may be social, linked to patient’s comorbidities, or due to surgery-related adverse events (e.g. pain, post-operative nausea and vomiting, etc.).

Using patient stratification, tailored surgical techniques and multimodal opioid-sparing analgesia, day-case TKA might be achievable in a limited group of patients. The younger, male patient without comorbidities and with an excellent social network around him might be a candidate.

Demographic changes, effective recovery programmes and less invasive surgical techniques such as unicondylar knee arthroplasty, may increase the size of the group of potential day-case patients.

The cost reduction achieved by day-case TKA needs to be balanced against any increase in morbidity and mortality and the cost of advanced follow-up at a distance with new technology. These factors need to be evaluated before adopting this ultimate ‘fast-track’ approach.

Cite this article: Bone Joint J 2015;97-B(10 Suppl A):40–4.

The patient with a painful arthritic knee awaiting total knee arthroplasty (TKA) requires a multidisciplinary approach. Optimal control of acute post-operative pain and the prevention of chronic persistent pain remains a challenge. The aim of this paper is to evaluate whether stratification of patients can help identify those who are at particular risk for severe acute or chronic pain.

Intense acute post-operative pain, which is itself a risk factor for chronic pain, is more common in younger, obese female patients and those suffering from central pain sensitisation. Pre-operative pain, in the knee or elsewhere in the body, predisposes to central sensitisation. Pain due to osteoarthritis of the knee may also trigger neuropathic pain and may be associated with chronic medication like opioids, leading to a state of nociceptive sensitisation called ‘opioid-induced hyperalgesia’. Finally, genetic and personality related risk factors may also put patients at a higher risk for the development of chronic pain.

Those identified as at risk for chronic pain would benefit from specific peri-operative management including reduction in opioid intake pre-operatively, the peri-operative use of antihyperalgesic drugs such as ketamine and gabapentinoids, and a close post-operative follow-up in a dedicated chronic pain clinic.

Cite this article: Bone Joint J 2015;97-B(10 Suppl A):45–8.

Three important objectives in knee arthroplasty are improving outcome, providing stability and obtaining correct alignment. Alignment has always been described either by anatomically measured alignment (short films, Knee Society Radiologic Score) or by mechanically measured alignment (HKA angle on long leg films). The difficulty of obtaining correct alignment in knee arthroplasty, is that as surgeons we need to find and use anatomical axes and landmarks, in the arthritic and often deformed knee, to align the implant well mechanically. Conventional instruments do the job well for 2/3 of patients, but for 1/3 we need some additional help. Navigation and patient-specific instruments (PSI) should make us more accurate surgeons.

Background

Finding the anatomical landmarks used for correct femoral rotational alignment can be difficult. The Posterior Condylar Line (PCL) is probably the easiest to find during surgery. The aim of this study was to analyze if a predetermined fixed angle referencing of the PCL could help obtain good femoral alignment in TKA patients.

Introduction

The importance of frontal and rotational alignment in total knee arthroplasty has been published. Together with conventional instrumentation, computer navigation has been used for many years now. The pro's and con's of navigation are well known since.

Total Knee Arthroplasty (TKA) has a tendency to change the individual anatomy of the patient within the limits of today used arthroplasty designs. Femoral external rotation will lead to mediolateral overhang by upsizing to avoid lateral notching and downsizing will lead to loss of posterior condylar offset. Posterior slope is usually reduced to avoid problems with posterior stabilized (PS) designs.

We compared 50 bicompartimental arthroplasties (Uni + PFJ) with 50 TKA's. Demographics and BMI are compared. We looked specifically at patient type, preoperative deformity, postoperative function and alignment and results on functional scores.

Bicompartimental arthroplasty is a resurfacing intervention that allows less correction of frontal deformity. Postop alignment was within 3° of varus. Better active flexion was obtained than in TKA. Better function was observed for stair climbing and single leg stability. Rotational position of foot was more natural in bicompartimental as compared to TKA. Functional scores like WOMAC, KOOS and IKDC showed better results for bicompartimental. Illness perception score showed that the resurfacing patient is another patient than the TKA patient. No overhang of components was observed. No change of posterior condylar offset was necessary. Posterior slope on the medial side was minimally reduced.

In conclusion resurfacing by bicompartimental arthroplasty with two individual components (Uni + PFJ) is an excellent solution to gender and ethnic differences. The individual anatomy of the specific patient goes through minimal changes resulting in better functional results.

Introduction: The aim of this study was to analyze the clinical importance of one single factor, the length of the skin incision in minimal invasive total knee arthroplasty.

Materials & methods: This was a prospective randomized single surgeon study. All patients were randomized for sex, age, diagnosis and BMI. In 40 consecutive knees, primary total knee arthroplasty was performed with minimal invasive instruments, through a 12 cm skin incision and a mini-midvastus approach. After cementation of the components and closure of the arthrotomie, half of the patients (20) were randomized (enveloppe technique) to have their skin incision extended from 12 to 20 cm.

The following data were assembled by a skin incision blinded study nurse: VAS, use of morphine pump, range of motion, straight leg raising, time to independent ambulation, time to discharge, wound problems and complications up to 6 weeks postoperative.

Results: For all these studied parameters there was no statistical significant difference between both study groups.

Conclusion: With this prospective randomized study we were able to analyze the functional effect of a larger skin incision in minimal invasive (MI) total knee arthroplasty and the placebo effect for the patient to see a smaller scar. We can conclude that the exact length of the skin incision is a non issue in MI total knee arthroplasty. Patients benefits are obtained by less soft tissue damage, the avoidance of patellofemoral and tibiofemoral dislocation and optimal patient management. We even believe that performing MI total knee arthroplasty through a comfortable incision could be advantageous. Shorter operating time, less skin bruising and avoidance of skin – implant contact can be obtained.

Introduction: Following the work of Freeman et al. on the medial pivot and roll back in the normal knee and several other studies on tibial slope we got interested in the subject. In most studies tibial slope is always measured on standard radiographs (lateral view) and therefore the medial and lateral side are superimposed.

Materials & methods: We studied the lateral view of the medial and lateral tibial plateau on a magnetic resonance scan (subchondral line). The study group (N=80) consisted of young patients (18–40 y) all consulting for patellofemoral problems with a non arthritic and stable knee. A neutral tibial axis was determined on the lateral view. Perpendicular to this axis the posterior slope of the medial and lateral compartment was measured. Statistical analysis was done.

Results: This analysis showed a mean posterior slope of – 5 ° ( range 0 ° – 12 °) on the lateral side, but an upslope on the medial side of + 7 ° ( range 5 °– 10 °). A significant statistical difference was noted between both.

Discussion: These results suggest an upslope on the medial side of the knee which could be important for deep knee flexion since this increases the posterior condylar clearance. Roll back on the medial side after 120° of flexion could be roll up of the condyle (2 mm). This could also explain the femoral external rotation (or tibial internal rotation) in natural knee flexion since the medial condyle rides up the medial meniscus and plateau allowing the lateral femoral condyle to roll down the lateral plateau during internal rotation of the tibia around the medial pivot point. This observation could explain paradoxical motion in total knee arthroplasty, since until now we made an equally sloped cut in both compartments.