When does Anterior Knee Pain occur?
Consensus statement on the implications of AKP
The medical profession is increasingly aware that AKP, while it often can be a minor problem that disappears after conservative management (non-steroidal analgesics, anti-inflammatories, physical therapy, bracing, and avoidance of the situations causing the pain), can become severe and prolonged, profoundly affecting quality of life.
A retreat of knee experts convened in 2016 in Manchester, UK, provided this statement, using the term 'patellofemoral pain', for AKP, acknowledging that it “… typically presents as diffuse anterior knee pain, usually with activities such as squatting, running, stair ascent and descent. It is common in active individuals across the lifespan, and is a frequent cause for presentation at physiotherapy, general practice, orthopaedic and sports medicine clinics in particular.
My personal involvement in developing this alternative approach to treating AKP – Case 1, the Index Case.
As a result of serendipitous observations during an arthroscopy early in my career in the military, I became aware that AKP is linked to the infrapatellar plica (IPP) and the fat pad, structures that fill the anterior compartment of the knee (see the sections on BACKGROUND ANATOMY). This was a single case, in which a very fit soldier, suffering from recalcitrant AKP, underwent arthroscopy. The articular surfaces of the knee were pristine, but there were two abnormalities. First there was a small zone of inflammation adjacent to the femoral attachment of the IPP. Second was the IPP itself, which on close examination, demonstrated mechanical behaviour, stretching visibly with motion. As the IPP was considered to be an embryological remnant of no clinical importance and with no mechanical or nutritional function, this represented a paradox. For me mentally, this was a ”Eureka moment”. With no other evidence of pathology in the knee, I released and resected the IPP, with immediate relief of the soldier’s pain. Prior to this case I had occasionally performed this simple procedure to improve visualization in the knee, but in this setting, the chronic pain was gone. With this unanticipated success, we developed a team of individuals, and sought the answer to the question: 'How does releasing/resecting the IPP help patients suffering from AKP?'
Our team members included: Dr. Kris Shekitka, a pathologist from the now-closed Armed Forces Institute of Pathology; Drs. Amos Race and Ken Mann, both biomedical engineers at the Institute of Human Performance, at Upstate Medical University; and, Dr. Oliver Portner, an orthopaedic surgeon and my senior colleague when I began my career. The practical clinical aspects of our research appeared in an article on 30 April, 2018, in Arthroscopy Techniques, an on-line, open access journal, entitled: 'Arthroscopic Untethering of the Fat Pad of the Knee: Release or Resection of the Infrapatellar Plica (Ligamentum Mucosum) and Related Structures for Anterior Knee Pain.'
This published article outlines the technique and scientific basis for the described simple, safe operation, which addresses AKP that is related to presence of the IPP-fat pad complex (see the sections on BACKGROUND ANATOMY...). We consider this concept an important addition to the knowledge base on AKP as it demonstrates a successful operation that can be performed early (we suggest 3-6 months) if non-operative management fails and is safe, having the complication rate of a diagnostic arthroscopy. We recommend this operation as the initial surgery performed for recalcitrant AKP.
Five clinical cases are listed in the chapters following this introduction to the course. The first two are typical of adult cases with no history of childhood AKP who develop the problem de novo in two typical scenarios, acute overuse (Case 1) and after injury (Case 2). The last three are of onset in adolescence, all occurring in association with the growth spurt, the first in a sedentary child (Case 3), the second in a track athlete with relative overuse (Case 4), and the last a dancer, also with overuse, but also with unique physiology and a psychiatric profile that produced devastating effects for this child (Case 5).
- Case 1 - Adult AKP – acute overuse. The Index Case
- Case 2 - Adult AKP – direct trauma
- Case 3 - Adolescent AKP, insidious onset, history of inflammatory arthropathy
- Case 4 - Adolescent AKP, insidious onset, varsity level track athlete, AKP associated with overuse, exacerbated by lateral release
- Case 5 - Adolescent AKP, insidious onset, profound psychological effect
Children are Special: We Consider their Surgical Treatment as Semi-Urgent.
Adolescent AKP seems to be a special group of patients as some children seem to be uniquely sensitive to the prolonged effect of AKP, perhaps because of its neuraligic nature. We presented our data on adolescent AKP, thinking that this patient group with a limited lifetime of injury, would demonstrate fewer confounding variables in assessing data with respect to AKP. In an Institutional Research Board approved study, conducted at Upstate Medical University and at Auburn Community Hospital, we collected our retrospective results over 18 years of practice; the data was purely retrospective, and thus was faulted on a scientific basis by the reviewers. We continue to seek to publish this article (The Infrapatellar Plica: A Major Cause of Chronic Adolescent Anterior Knee Pain, relieved by Arthroscopic Resection) because of the importance of the results. Present practice is to avoid surgery because conservative management works in many and the complication rate for surgeries that re-align limbs or reconstruct the soft tissues about the patella is of the order of 25%.
Scott Dye, an acknowledged knee expert, writing on the impact of such complications, commented on this: “…The treatment algorithms that follow from the nearly exclusive consideration of such structural data (including excessive use of the lateral retinacular release, aggressive chondroplasties, and proximal and distal realignments) unfortunately often have resulted in the worsening of the patient’s symptoms…”.
The natural history of adolescent AKP has been studied. In many adolescents, the condition is benign and self-limited in many; however, in 25% to 45% pain becomes chronic with long-term sequelae, both physical and mental. Our approach, that of performing a diagnostic arthroscopy, especially when the IPP-fat pad complex is present, was for patients whose conservative management has failed.
We operated on 49 patients over 18 years, and were able to contact and evaluate 35 patients, with 49 knees operated. These patients had failed conservative management, and had no option other than living with their pain. Every patient had the IPP-fat pad complex. The result was good to excellent in 84% of knees, with an average follow-up of 64 months, with no complications. Fair or poor ratings were given for those patients who still had some pain, even though all but one had improved scores. The one knee that did not improve also did not worsen, being essentially unchanged by the surgery. 41 knees had no pain, and full function, some after years of disabling pain -- remarkable success for a condition considered untreatable.
The clinical cases listed above of chronic adolescent AKP are typical examples, each involving years of suffering, changed to a return to normal life after arthroscopic surgery that included defining and addressing the problems present.
Diagnostic arthroscopy, with appropriate intra-articular surgery, including untethering of the fat pad, is recommended for children who fail after 3 months of conservative management.