http://www.healio.com/orthopedics/blogs/patellofemoral-update
Variability in tibial tubercle to trochlear groove distance and measurements of malalignment
In the assessment of patellar instability, malalignment is an important factor to consider in determining the appropriate surgical treatment. Mechanical variations, such as excessive femoral anterversion, genu valgum or external tibial torsion, can increase the lateralization of the tibial tubercle and contribute to patellar instability. Identifying such factors can aid in determining the optimal surgical options for a patient, particularly with respect to tibial tubercle osteotomy. Realigning t...
Anteromedial tibial tubercle transfer is a powerful procedure to control patellofemoral pain, instability
Anteromedial tibial tubercle transfer, originally described in 1983, effectively moves the patella from tracking laterally and thus unloads the lateral patella while making the patellofemoral joint more congruous and stable. Additionally, because the tibial tubercle is also moved anteriorly, the distal pole of the patella is lifted up thereby unloading distally located patella articular lesions that may be a source of pain. Such lesions are fairly common in association with a lateral tracking, painful patella.
Is there any indication for trochleoplasty?
Trochleoplasty for patients with recurrent patellar instability has been debated the past few years. The procedure is becoming more common in Europe, while orthopedic surgeons in the United States have a more cautious approach, although a few surgeons are doing the procedure. One can ask if there is a need for trochleoplasties when there are other well-established procedures.
Many surgeons are excited about medial patellofemoral ligament (MPFL) reconstructions. Some studies with long-term follow-up seem to have good results; however, it is not a solution for all patients with patellar instabilities. We have to be aware of the underlying pathomorphology. In a recent meta analysis, Shah and colleagues found a complication rate of 26% after MPFL reconstruction. A major complication was postoperative instability with recurrent apprehension, which was 32% of all complications. Howells and colleagues found that 15 of 25 patients with persistent recurrent symptoms after reconstruction of the MPFL had moderate trochlear dysplasia. Patients with severe trochlear dysplasia already had been excluded.
Catastrophic thinking is a new puzzle piece in understanding anterior knee pain
Anterior knee pain is one of the most common reasons to consult an orthopedic surgeon who specializes in the knee. Despite the high frequency of anterior knee pain, its etiopathogeny is not well known and myths about the condition are widespread. One myth is the patient with anterior knee pain as a patient with peculiar psychological traits responsible for the genesis of pain.
Many patients with anterior knee pain (AKP) have insubstantial clinical and radiologic findings. However, their pain and disability are important. If we add in the allodynia and hyperalgesia that many patients have, then we could be led to believe that the problem is psychological. This is not true. Patients with AKP have a high incidence of anxiety, depression, kinesophobia (the belief that movement will create additional injury or re-injury and pain) and catastrophizing (the belief that pain will get worse and one is helpless to deal with it). However, it is also true that these psychological disorders are the result of the pain severity but not the cause of the pain and disability.
Is anatomic femoral tunnel position important in medial patellofemoral ligament reconstruction?
Biomechanical studies have shown increased medial patellofemoral force and pressure with a malpositioned femoral tunnel. Clinical reports describe knee pain, medial patella overload, medial patella subluxation and knee stiffness in select cases with femoral tunnel malposition. However, larger clinical studies have not shown any correlation with tunnel position and clinical outcome at short-term follow-up.
Servien and colleagues had 10 of 29 femoral tunnels malpositioned on MRI but no difference in outcomes when comparing groups. McCarthy and colleagues evaluated postoperative radiographs in 60 patients and found 65% of femoral tunnels were malpositioned. However, there was no difference in clinical outcomes.
Lateral facetectomy can improve symptoms of patellofemoral osteoarthritis
Isolate patellofemoral osteoarthritis is a relatively common condition. In a radiographic study of patients older than 40 years who had painful knees, Davies and colleagues noted that the prevalence of patellofemoral osteoarthritis (PFO) was 9% (19 of 206 knees).
McAlindon and colleagues found the presence of isolated patellofemoral degeneration in 12% of men and 26% of women in patients with knee pain who were older than 55 years. In patients older than 55 years without knee pain, the prevalence was 5% in both men and women. They concluded from this study that PFO is common, associated with disability, occurs in the absence of tibiofemoral disease, and can no longer be omitted from future studies of the osteoarthritis of the knee joint.
Patellar alta: More precise measurements are needed for operative management
Patella alta has been a known associated factor of recurrent lateral patella dislocations for decades. The Lyon group recognized patella alta as and one of four main “objective” patella instability risk factors, and suggested distalization of the tibial tubercle as a surgical solution for the problem.
The biomechanical result of patella alta is decreased bony constraint secondary to the delayed entry of the patella into the trochlear groove, thus there is a greater arc of knee motion in early flexion in which the patella is potentially subjected to lateral forces leading to a patella dislocation. This delayed entry into the groove is magnified in the face of trochlear dysplasia when there is a shortened or shallower groove as well. This delayed entry also alters the patellofemoral contact area, which in conjunction with known forces at early flexion angles, results in an increase in patellofemoral (PF) stress. This increased stress could lead to pain and chondral wear.
With the historical backdrop of patellar infra contraction syndrome (PICS), many U.S. surgeons have been hesitant to treat patellar alta. Surgeons now realize that optimizing patellar height can be performed without causing patella infra. However, distalization of the tuberosity with poor surgical technique or wrong indications can lead to disastrous results.
Is there a role for medial-sided repair in patellar instability?
Historically, combinations of proximal and distal realignment procedures have been used to address patellar instability.
The proximal realignment procedures include medial retinacular repair, medial imbrication, VMO advancement, medial patellofemoral ligament (MPFL) repair or medial capsular reefing, with or without lateral retinacular release. Although several level 4 case series have shown satisfactory results with these proximal realignment procedures, there are at least four level 1 studies which have failed to show a difference between these medial-sided repairs and nonoperative treatment.
Arthroplasty vs. joint preservation in young adults
Treatment of full-thickness patellofemoral chondral lesions in young patients remains a challenge. The goal of restoring hyaline cartilage that possesses normal structural and mechanical properties has been particularly difficult to achieve in the patellofemoral joint. Treatment options include marrow stimulation techniques, osteochondral autograft or allograft transfer and various autologous chondrocyte implantation (ACI) techniques. Concomitant correction of anatomic abnormalities, such as tibiofemoral or patellofemoral malalignment, appears to improve the results of such restoration procedures.
Recognize the unique characteristics of the patellofemoral compartment
Unfortunately, the general treatment options for cartilage restoration in the United States have remained somewhat stagnant for more than 15 years. Fortunately, within this static group of specific cartilage treatments, orthopedic surgeons have expanded treatment options in the knee and other joints.
Initially, the technique was primarily used for femoral lesions. With relative success in those areas, surgeons gradually expanded the techniques to the patellofemoral (PF) compartment. While the compartment obviously has the same type of articular cartilage as the tibiofemoral (TF) compartments, certain factors are essential to optimize outcomes.
First and foremost, cartilage is aneural. Therefore, it must be appreciated that the cartilage lesion is secondarily contributing to the patient’s pain. The source of the pain must be exhaustively investigated. Cartilage treatment only should be contemplated after failure of thorough physical therapy (with up-to-date patellofemoral specific techniques) and adherence to the “envelope of function” principles by Scott Dye, MD.
Develop functional approach to exercise for patients with patellofemoral pain
While many advocate a functional approach to exercise for patients with patellofemoral pain, isolated muscle weakness can lead to bad compensation patterns in weight-bearing exercise if the strength impairment is not addressed first. The eternal open chain vs. closed chain, isolated versus multi-joint exercise argument is derivative. Why set up an either-or unnecessary forced choice?
Arthroscopic patella realignment: Don’t forget minimally invasive stabilization
There has been great emphasis recently on invasive methods of medial patellofemoral ligament reconstruction for patella instability. Although these techniques can be effective and appropriate for severe cases of instability caused by medial patellofemoral ligament insufficiency, it is important to keep perspective on the appropriate indications for these techniques.
Medial patellofemoral ligament (MPFL) reconstruction with a graft is indicated when the native MPFL is incompetent, and the remaining native tissue is inadequate to be repaired or reefed primarily. However, in many cases of mild or moderate instability, a simple reefing of the MPFL is a highly successful procedure, whether done arthroscopically or by mini-open techniques, and is a much less invasive procedure.
Numerous studies have been published documenting the effectiveness of arthroscopic realignment for patella instability, with success rates of more than 90% and no or minimal complications. Although effective, MPFL reconstruction is an open invasive procedure fraught with potential complications including patella fracture, over-tightening, and non-isometric placement of the graft resulting in pain stiffness and medial tracking.
Distalization of the patella to correct patella alta in patients with patella instability
The review of the available literature by Robert A. Magnussen, MD, on this topic is timely as orthopedic surgeons are increasingly interested in the correction of patella alta to control patella instability. Distalization of the tibial tuberosity brings the patella into the deeper part of the trochlear groove sooner in knee flexion, thereby affording improved stability and diminished likelihood of dislocation. When the trochlea is shallow, distalization makes sense.
As pointed out by Magnussen et al, the question remains as to when other procedures such as medial tubercle transfer or reconstruction of the medial capsular structures, including the medial patellofemoral ligament (MPFL), might be warranted in addition to, or instead of, patella distalization. Many surgeons have achieved patella stability for years by assuring proper alignment/tracking of the patella in the trochlear groove and then restoring, by reconstruction, the medial support structures that support the patella as it slides along the trochlea with flexion and extension of the knee.
Avoid overtreatment of patellofemoral chondrosis/arthrosis in the athlete
Patellofemoral chondrosis/arthrosis is extremely common. It is often an incidental finding and has been reported in almost 50% of MRIs in asymptomatic players of the National Basketball Association.
The articular cartilage is aneural and most pain originates in the soft tissues. The treating orthopedic surgeon must be careful in attributing a patient’s anterior knee pain to the presence of a patellofemoral articular cartilage lesion. Often times, they are incidental findings and it is imperative to search for other causes. Most patellofemoral pain will go away if treated conservatively despite the presence of a significant articular cartilage lesion. Always look at the soft tissues closely as a source of pain.
Paper underlines importance of patient counseling in maintenance of ideal body weight
Anterior knee pain is one of the most common complaints in an orthopedist's office. Some patients have pain due to abnormalities of the patella tracking over the trochlea, but a significant number of patients have normal X-ray parameters indicating normal alignment and no clinical evidence of maltracking. Many of these patients are significantly, if not severely overweight presenting with a body mass index of 40 and higher. These patients likely overload the patellofemoral joint. It is important to understand that, while all lower extremity joints suffer from high body mass, the patellofemoral joint sees the highest loads (7 to 10 times body weight) with every step the patient takes.
Primum non nocere: MPFL reconstruction complications
This case series by Panikh and colleagues reviews the authors’ experience with complications after medial patellofemoral ligament reconstruction. I greatly appreciate their honestly and willingness to publish and emphasize complications related to this procedure. Much too often authors emphasize and readers remember only the success rates of surgical procedures.
The patient population included 179 patients with recurrent patellar instability. They determined by retrospective record review with more than 3-year follow-up that 16% of their patients developed complications including recurrent instability, stiffness, pain and patella fractures. Their medial patellofemoral ligament (MPFL) technique evolved somewhat away from more aggressive patellar tunnels (to avoid fracture), but for the sake of consistency it did not include lateral release in any patients. According to the Materials and Methods section, the preoperative evaluation included tibial tuberosity-trochlear groove (TTTG) analysis although those results were not reported. It would be interesting to know if the patients who had recurrent instability had increased TTTG measurements compared to the more successfully treated patients.
Diagnosis and treatment of patellofemoral disorders must be individualized
After reading an article from Pagenstert and colleagues on lateral retinacular release vs. lengthening, I was compelled to respond with a letter to the editor. I was surprised and disappointed that an orthopedic surgeon would design a study using a 22-year-old technique that was said to assure an “adequate” release (the “90° turn-up” test), even cutting the vastus lateralis tendon if necessary to achieve this goal, and leave it unrepaired. Severing the vastus lateralis tendon is known to cause iatrogenic medial patellar subluxation and permanent disability in a high proportion of patients. Indeed, about one third of their release-only patients have this totally predictable fate.
Patellofemoral pain: Where does it originate and how to get rid of it
Pain in the front of the knee is usually called patellofemoral pain, but may originate in any of innervated structure around this part of the knee, or be referred from the hip or back. Anterior knee pain walking down stairs or running is a fairly common cause of time lost from sports and vigorous activity. Irritation of structures around the patella – retinaculum and synovium – from overuse or imbalances also can cause pain. Such anterior knee pain will usually get better with rest ...
