Is it better to resurface the patella or index knee?
It is best to primarily resurface the patella because there are unpredictable and generally poor results associated with secondary resurfacing for painful TKA when the patella was not resurfaced at the index procedure. Over 50% of patients report continued anterior knee pain and are dissatisfied with the procedure [11, 12].
Does secondary resurfacing work for hot patella?
Part of the problem is correctly diagnosing the patella as the cause of anterior knee pain. In patients with anterior knee pain and a bone scan identifying a “hot patella”, there were good results for secondary resurfacing. However, in patients with generalized knee pain and a “hot patella,” secondary resurfacing showed poor results [13] .
What happens if you don’t resurface your patella?
The reoperation rate is higher when the patella is not resurfaced. The clinical results of a subsequently resurfaced patella are generally unpredictable because there is an underlying problem. If you have malrotation, resurfacing the patella isn’t going to solve it. Clinical results are similar.
What are the indications for resurfacing of the patella?
For those who selectively resurface, the relative indications for surfacing the patella include the presence of anterior knee pain, notably damaged articular cartilage, old age, inflammatory arthritis, isolated patellofemoral arthritis, patellar subluxation and maltracking, implant design, and obesity.
Should the patella be resurfaced during total knee replacement?
Currently, there are 3 surgical approaches to the patella during primary total knee arthroplasty: always resurface, never resurface, or selectively resurface based upon patient factors such as quality of the articular cartilage and patellofemoral congruence at the time of surgery.
Is knee resurfacing the same as partial knee replacement?
One of the premier alternatives of total knee replacement surgery is a relatively new treatment technology called knee resurfacing. We offer it at Orthopaedic & Spine Center (OSC). It is also referred to as partial knee replacement, Partial Knee Arthroplasty (PKA) or Uni-Compartmental Knee Replacement.
What can be done for a failed knee replacement?
If your knee replacement fails, your doctor may recommend that you have a second surgery—revision total knee replacement. In this procedure, your doctor removes some or all of the parts of the original prosthesis and replaces them with new ones.
What does resurfacing of the patella mean?
Patellofemoral knee resurfacing: is a procedure that resurfaces the worn patella and trochlea of the femur (the grove at the end of the thigh bone) that together make up the patellofemoral joint.
How long does it take to recover from knee resurfacing?
Most patients can expect to be back to their daily activities within three to six weeks. Many patients find that after undergoing physical rehabilitation, they are able to return to sports such as golf within 6 to 10 weeks.
What is the success rate of partial knee replacement?
Many studies show that more than 90 percent of partial knee replacements are still functioning well 10 years after the surgery.
How many times can a knee revision be done?
In 85% to 90% of people who have a total knee replacement, the knee implants used will last about 15 to 20 years. This means that some patients who have a knee replacement at a younger age may eventually need a second operation to clean the bone surfaces and refixate the implants.
What is the newest procedure for knee replacement?
Minimally-invasive quadriceps-sparing total knee replacement is a new surgical technique that allows surgeons to insert the same time-tested reliable knee replacement implants through a shorter incision using surgical approach that avoids trauma to the quadriceps muscle (see figure 1) which is the most important muscle ...
What is the most common reason for knee revision surgery?
The most common reasons for knee revision surgery are: attachment between the artificial joint and the bone has become loose. infection of the joint may cause stiffness, pain or loosening. fracture of the bone around the joint requires the fracture to be fixed.
How do they resurface a kneecap?
Isolated patellofemoral resurfacing is a procedure in which only the worn out and bare bone surface of the under surface of the kneecap or patella and the front surface of the femur (trochlear) are resurfaced with a metal prosthesis for the trochlear and a polyethylene or plastic surface cemented onto the patella.
How is knee resurfacing done?
1:535:06What is Knee Resurfacing - Dr. Richard Ursone - YouTubeYouTubeStart of suggested clipEnd of suggested clipAnd so what you do is you kind of drill out the surface that's worn down and then it's a fairlyMoreAnd so what you do is you kind of drill out the surface that's worn down and then it's a fairly simple cap that will load on to a little screw that goes into the bone.
What is the patellar shape?
The great majority of currently available patellar components are of the all-polyethylene dome-shaped type (Fig. 113-9; see also Fig. 113-14 ). Dome-shaped components usually articulate congruently with the trochlear groove in extension but may be exposed to high stresses and point contact in flexion, when the patella comes into contact with the convexities of the femoral condyles. Some of these problems have been addressed successfully through design adaptations of femoral condylar and trochlear geometries. Extension of the trochlear groove concavity onto the inner portion of the femoral condyles has allowed for an increase of patellofemoral congruency in flexion. In addition, the round-on-round shape of the articulation permits patellar tilt to occur without excessive edge loading, a problem associated with modified dome-shaped and anatomic patellar devices. However, failure of cemented, all-polyethylene dome-shaped patellar components is not uncommon; this has been attributed to the exposure of increase shear stresses in vivo, especially in malpositioned components. 22,98,137,331
How does external rotation affect patella?
212 External rotation moves the trochlear groove toward the natural position of the patella, thereby relaxing the lateral retinacular structures and reducing the lateral force vector acting on the patella. Second, it also corrects any mismatch in the flexion-extension gap created through cutting the proximal tibia perpendicularly to its long axis, rather than emulating its natural varus alignment. This can be achieved through the relative thickness of bone removed from the posterior femoral condyles, but care must be taken to establish a rectangular flexion gap; otherwise, knee stability in flexion may be compromised. Any instrumentation for distal femoral preparation that references femoral component rotation on the posterior condyles would, if left unadjusted, place the femur in internal rotation relative to the transepicondylar axis. Posterior condylar referencing therefore requires the surgeon to dial in a degree of external rotation to achieve parallel cuts to the transepicondylar axis (TEA), which has created what is referred to as external femoral rotation. Whiteside and coworkers 211 have found the patellar tracking pattern and contact areas to be most normal when the femoral implant is externally rotated by approximately 5 degrees in relation to the PCA. 10 External rotation angles beyond 5 degrees, however, appear to have a detrimental effect on the spatial position of the patella in the trochlea. 13 Because of the variability in the relationship between the posterior condylar axis (PCA) and TEA, this technique carries certain dangers. Although the main difference between the two axes is 3 degrees of internal rotation, the range is 0 to 10 degrees, with higher values for valgus knees. 219 The risk of femoral malrotation is thus higher in the valgus knee, especially if a somewhat hypoplastic posterior lateral femoral condyle has been used as a reference for rotational alignment when making anteroposterior cuts. The situation is usually compounded because the internally rotated femur necessitates subsequent internal rotation of the tibial component to establish rotational tibiofemoral congruency, thus creating excessive external rotation of the tibial tuberosity and patellar maltracking.
What is the relationship between patella and femoral joint?
For example, increasing the congruency of the patellofemoral articulation reduces peak stresses on the surface level of the components but, in turn, increases shear stresses at the patellar fixation site. From a wear point of view, an increase in component conformity would appear advantageous. 21 Overconstraining the joint, however, is incompatible with secure fixation and freedom of motion. It is therefore reasonable to suggest a compromise solution that provides partially conforming surfaces that may satisfy reasonable motion, laxity, and stability between patella and femur. This concept of partial patellofemoral conformity has been incorporated successfully into most knee implant systems, but some mobile-bearing devices have defied science and have performed well, despite highly congruent surface geometries. 43,153,161
How does patellar moment arm affect knee flexion?
They are increased if the axis is deviated posteriorly from its physiologic position. Femoral rollback facilitates this process and represents a characteristic feature of normal knee kinematics. Increased rollback effectively lengthens the patellar moment arm thus increasing the efficacy of the extensor mechanism. D’Lima and associates 75 have investigated the influence of various degrees of posterior femoral rollback on patellofemoral compressive forces. Femoral rollback resulting from PCL preservation produced reductions in patellofemoral compressive forces of up to 7% throughout knee flexion, whereas the effect in PCL-substituting devices only became noticeable after cam-post engagement, with a maximum effect recorded at 85 degrees of knee flexion. Miller and colleagues, 205 in an earlier study comparing PCL-retaining with PCL-substituting arthroplasties, failed to note femoral rollback when the PCL was retained. They stipulated that the absence of the anterior cruciate ligament may render the PCL ineffective, which may explain the appearance of paradoxical movements (reverse rollback) 75 observed on fluoroscopic investigation. 68–70 Although PCL substitution kept patellofemoral forces close to the level of the native knee, a lateral release became necessary in 50% of knees, raising potential concerns about an increase in patellofemoral stress through ligamentous tension. This concept has also been expressed by Ranawat and Sculco 233,235 who raised concern that femoral rollback, through a cam and post mechanism, as in posterior-stabilizing designs, or through a functional posterior cruciate ligament (PCL), may increase tensile forces across the patella in flexion. Overstuffing will tighten the extensor mechanism, and increase anterior patellar strain and PRF, with the likely consequences of loss of flexion, patellar implant failure, and fracture. 78,204,235,303 Overall patellar thickness following resurfacing should therefore not exceed preoperative values. With regard to clinical outcomes, Waters and Bentley 320 have assessed the occurrence of postoperative anterior knee pain in 327 cruciate-substituting and 147 cruciate-retaining TKAs, but found no significant difference.
What is the PRF in physics?
Figure 113-4 The PRF bisects the angle made by the quadriceps and patellar tendon forces and moves upward on the patella with flexion. The TRF occurs through engagement of the quadriceps tendon with the femoral trochlea at 50 to 90 degrees of flexion (turn-round of forces), providing a load-sharing function to the patella. In the coronal and axial views, the sideways component is balanced by the reaction occurring on the slope of the femoral trochlea.
How many degrees does the patellar tendon move?
Depending on the length of the patellar tendon, the patella is drawn into the trochlea from a slight lateral position and gains contact with the femur between 10 and 20 degrees. The contact begins with the inferior margin of the patella and moves proximally as flexion proceeds.
Why should dome patellas not be generalized?
However, advantages attributed to a particular design, such as the dome-shaped patella, should not be generalized to all domes because the behavior of a specific patellar component is directly dependent on a number of variables, with the surface geometry of the mating femoral component being the most important.
Why is a patella resurfaced unpredictable?
The clinical results of a subsequently resurfaced patella are generally unpredictable because there is an underlying problem. If you have malrotation, resurfacing the patella isn’t going to solve it. Clinical results are similar. Indications for revision are unclear.
Why aren't patella complications reported?
What about the resurfaced patella? The problem is all the complications are not reported to a registry because they’re not implant related, in that you’re not putting in an implant. Usually you’re just taking out an implant. And the results vary by type.
What percentage of knee replacement patients are not happy with their total knee replacement?
Twenty percent of knee replacement patients are not happy with their total knee replacements. What role could patella resurfacing (or not) play? Two giants of knee replacement, Robert Barrack and Steven Haas, tackle this very critical topic.
Why is my knee not quite right?
Something’s not quite right and because of that you get loosening on one side and fracture and fragmentation on the other side. This is the type of thing we see with regularity. These are very serious complications and the knee is never quite the same.
Is knee pain a symptom of knee replacement?
Dr. Barrack: Anterior knee pain is very common. Maybe the most common symptom after knee replacement. The misconception is that it’s from an unresurfaced patella. In my experience, it is far more common that this patient has a resurfaced patella that isn’t quite articulating well. Knee pain—this is something we see day in and day out and it’s usually with a resurfaced patella.
Can you resurface patella?
Clinical results are similar. Indications for revision are unclear. If the patient has diffuse pain and you resurface their patella, it’s going to make your revision rate look higher, but they’re actually just problems with the indications.
Can lateral facet be revision?
A paper from the Mayo Clinic showed that lateral facet pain can require revision so they looked at 15-20 cases, but 99% of surgeons are not aware of this option (Nikolaus, et al., JOA ). They don’t perform this procedure.
Why is it important to resurface the patella?
It is best to primarily resurface the patella because there are unpredictable and generally poor results associated with secondary resurfacing for painful TKA when the patella was not resurfaced at the index procedure. Over 50% of patients report continued anterior knee pain and are dissatisfied with the procedure [11, 12]. Part of the problem is correctly diagnosing the patella as the cause of anterior knee pain. In patients with anterior knee pain and a bone scan identifying a “hot patella”, there were good results for secondary resurfacing. However, in patients with generalized knee pain and a “hot patella,” secondary resurfacing showed poor results [13] . Secondary resurfacing in patients with knee pain and a “cold patella” similarly showed poor results [11].
How thick is a patella?
technical considerations. The patella is between 22-26 mm thick. After resurfacing, a minimum bony thickness of 12 mm is necessary to avoid fracture. The goal is to replicate the native patellar thickness, ie 22-26 mm. It is critical to obtain a flat patellar cut (commonly too much bone is resected from the medial side, increasing risk of fracture). Best results for patellar resurfacing include: maximizing size of patellar button without overhang (this decreases crepitus) [14], error on side of increased patellar thickness (concern for "overstuffing" is not demonstrated in literature), place component slightly superiorly to avoid patella baja, slightly medialize to improve tracking [15], inlay fixation is better than onlay.
Which joint has the thickest cartilage?
The patella has the thickest cartilage in the body due to the high level of forces in the patellofemoral joint. And yet, a TKA further increases these forces 3x, exposing the patella to super-physiologic loads and possibly leading to acute symptoms or accelerated chondrolysis and later pain. technical considerations.
When was knee replacement first performed?
These patients reported anterior knee pain in over 50% of cases [1]. The first patellar resurfacing options appeared in the early 1970s, yet 6% experienced lateral patellar dislocation. Changes in TKA design and improved alignment techniques have significantly reduced this risk to < 1%. However, patella resurfacing still presents with its own unique risk of complication including fracture, mal-alignment and subluxation. Furthermore, while modern designs have reduced the incidence of anterior knee pain to about 10%, the number remains significant and thus the underlying etiology of anterior knee pain remains unclear. [2] [3].
What is the patella?
The patella is a mobile fulcrum increasing the extensor mechanism's mechanical advantage at all positions of knee motion. The extensor mechanism is 50% weaker in a knee without the patella. The patella is subject to considerable forces, 5x body weight rising from a chair, 2x body weight going up stairs, and 20x body weight with jumping.
Is patellar resurfacing benign?
Resurfacing the patella is not a benign procedure. The complication rate for patellar resurfacing is between 3-7%.
Is resurfacing the patella benign?
The patellar offset and lateral patellar tilt are both decreased in a resurfaced patella, which appear to alter patellofemoral pressure and kinematics, as compared to a native knee, and may be related to anterior knee pain [18]. Resurfacing the patella is not a benign procedure.
What is the procedure for patella resurfacing?
He noted surgeons can choose to perform patella resurfacing with either an inlay technique, which involves reaming into the native patella and leaving the perimeter and the rest of the patella untouched, or an onlay technique, which involves removing the articular surface across the patella and measuring for the appropriately sized patella implant which is fixed to the top of the patella.
Why should young patients not undergo patella resurfacing?
Nunley said young patients should not undergo patella resurfacing because of the likelihood they may need to undergo added procedures in the future to replace the implant.
Why is it important to not resurface a patella?
Those surgeons in the unresurfaced patella camp argue that an advantage of not resurfacing is that patients have no risk of potential implant complications , according to Lieberman.
What is the importance of trochlear groove?
Within the past 2 decades, implants began to appear that had a more accurate trochlear groove anatomy, which is important for successful long-term survivorship and outcomes in conjunction with accuracy of alignment and rotation and limited use of lateral release, Berend said. In addition, modern implants with a femoral component specifically designed with a patella that is both friendly to the native patella and accepting of a resurfaced patella, such as the Klassic Knee System (Total Joint Orthopedics Inc.), may reduce complications, such as patella clunk syndrome, he said.
Does Berend resurface patella?
Berend said he does not resurface the patella among patients who are being operatively converted from a partial knee replacement to a total knee replacement due to a risk of lateral ulcer, lateral fissure or cartilage loss in the lateral compartment if they have a normal kneecap.
Is patella resurfacing dependent on surgery?
In addition to choosing an appropriate implant, Spangehl said reducing complications in patella resurfacing is also dependent on the surgical technique.
Does patella resurfacing reduce knee pain?
Despite literature that suggests there is reduced knee pain when the patella is resurfaced during TKA, Ryan M. Nunley, MD, associate professor in the department of orthopedic surgery at Washington University in St. Louis, said some research has shown no difference in anterior knee pain incidence when revision surgery for patella resurfacing.