Abstract
Isolated patellofemoral osteoarthritis is not uncommon, and treatment remains controversial. Several surgical procedures have been performed to treat this condition. The success of surgery highly depends on the technique and the patient selection. The surgeon can choose between a relatively extreme total knee replacement, with predictable results, or operations demanding less surgical dissection and resection, but offering less certainty. Partial lateral facetectomy is a minimally invasive procedure that is simple and effective enough in selected patients with up to 10 years follow-up. An even less aggressive technique, the arthroscopic partial lateral facetectomy in combination with lateral retinacular release, has been shown to be safe, practical, reproducible, and with a low rate of complications and revision surgery at mid-term follow-up. Benefits of arthroscopic techniques include decreased bleeding, less postoperative pain, ability to treat concomitant pathology, and better cosmesis.
The success of medical treatments highly depends on the therapeutic choice and on the selection of the patient. Each patient presents us with a unique combination of anatomic features, in the setting of their own needs and goals. It falls on us to advise the various options and surgical procedures with the patient’s best interest in mind.
Isolated patellofemoral osteoarthritis (PFOA) is now recognized to be more common than previously thought. The overall crude prevalence of PFOA in people with knee pain aged 30 years and older has been reported to be up to 39%
1
, and in 89% of patients, it affects the lateral facet.2
The cause of pain is not always clear, and the clinical symptoms do not always correlate with cartilage lesions.3
,4
Fortunately, the majority of patients with isolated patellofemoral degenerative changes are not symptomatic and do not need treatment. When symptomatic treatment of PFOA in the healthy middle-aged population is necessary, it is highly challenging and controversial. When all conservative therapies have failed, surgery becomes necessary. Several surgical procedures have been performed to treat this condition.
Partial lateral facetectomy is a minimally invasive procedure, simple and effective enough in selected patients up 10 years after the surgery.
5
Benefits of the arthroscopic techniques generally include decreased bleeding, less postoperative pain, ability to treat concomitant pathology, and better cosmesis. The arthroscopic lateral patellar facetectomy, first described by Ferrari,6
may be a satisfactory solution to treat isolated symptomatic PFOA.The study “Arthroscopic Lateral Patellar Facetectomy and Lateral Release Can Be Recommended for Isolated Patellofemoral Osteoarthritis”
7
by Douiri, Lavoué, Galvin, Boileau, and Trojani, demonstrates sustained significant improvement in knee clinical outcome scores and pain with a low rate of complications and revision surgery at mid-term follow-up by means of this minimally invasive procedure. This retrospective monocentric study offers another therapeutic option for a not inconsiderable group of patients.These authors retrospectively studied a group of 61 knees in 55 patients (44 of them clinically and radiologically) that underwent an arthroscopic lateral patellar facetectomy and lateral release for a diagnosis of isolated PFOA, at a mean follow up of 7.5 years.
The arthroscopic resection technique, followed by a complete section of the lateral patellar retinaculum is well described by the authors. The mean visual analog pain scale decreased, as well as Knee injury and Osteoarthritis Outcome Score and International Knee Documentation Committee scores improved significantly after the procedure. The patients were studied until they underwent a total knee replacement (TKR) on any revision surgery. The mean time from arthroscopic facetectomy to revision surgery was 47 months (range: 5-114 months).
There is currently no consensus on the most appropriate management of isolated PFOA. Both excessive lateral pressure syndrome and permanent lateral subluxation lead to lateral PFOA. Therefore, a lateral patellar facetectomy and lateral release will relieve pain and improve function in this group of patients. The use of arthroscopy for this purpose will help our patients who will benefit from the advantages of the arthroscopic technique.
Although the study of Douiri et al. is well presented and worthy of further study in a wider group of patients, some limitations are observed, and the interpretation of the results could be tough. The researchers reported a significant improvement of the radiological assessment of the PFOA according to the Iwano classification.
2
Nevertheless, the difference in the last follow-up is not statistically significant despite the authors reporting an improvement in the lowest Iwano’s stages. Also, the authors do not describe the congruence angle before or after the index operation, but they reported a significant improvement of lateral patellar subluxation at final follow-up (from 57% of lateral patella subluxation before the surgery to 15% at the last follow-up). López-Franco et al. have reported5
lateral patella subluxation in 27% of patients that did not undergo a TKR after partial lateral facetectomy at a minimum of 10 years follow-up and 52% in the patient group that needed the knee replacement. Moreover, trochlear dysplasia has been hypothesized to play a role in the onset of isolated PFOA, and its prevalence in a group of 101 knees that underwent vertical facetectomy was 88.1%.8
On the other hand, the authors did not observe any tibiofemoral osteoarthritis using the Ahlbäck scale preoperatively, and 36% of patients at the last follow-up ranged in mean age of 59.4 years (SD: 12 years). Apparently, the tibiofemoral OA progression is the most important cause of failure after a partial lateral facetectomy. Maybe, the Outerbridge classification could be helpful to decide a more suitable procedure.
The fact that they did not study standard weight-bearing AP view radiographs or computed tomography scanning could be another limitation of this study.
Partial lateral facetectomy in combination with lateral retinacular release can be recommended in cases of symptomatic isolated PFOA in properly selected patients with a normal valgus vector at the patellofemoral mechanism. In spite of the possible limitations of this recent study, the authors describe in a simple way an even less aggressive technique using arthroscopy and the outcomes at mid-term follow-up of a fairly large group of patients with a significant clinical improvement and without major complications.
Supplementary Data
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References
- The prevalence of patellofemoral osteoarthritis: A systematic review and meta-analysis.Osteoarthritis Cartilage. 2016; 24: 1697-1707
- Roentgenographic and clinical findings of patellofemoral osteoarthrosis.Clin Orthop Relat Res. 1990; 252: 190-197
- Conscious neurosensory mapping of the internal structures of the human knee without intraarticular anaesthesia.Am J Sports Med. 1998; 26: 773-777
- Current concepts review. Patellar malalignment.J Bone Joint Surg Am. 2000; 82A: 1639-1650
- Evaluation of a minimally aggressive method of patellofemoral osteoarthritis treatment at 10 years minimum follow-up.Knee. 2013; 20: 476-481
- Arthroscopic patellar lateral facetectomy.Arthrosc Tech. 2017; 6: e357-e362
- Arthroscopic lateral patellar facetectomy and lateral release can be recommended for isolated patellofemoral osteoarthritis.Arthroscopy. 2022; 38: 892-899
- Prevalence of trochlear dysplasia in symptomatic isolated lateral patellofemoral osteoarthritis: Transverse study of 101 cases.Orthop Traumatol Surg Res. 2021; 107: 102895
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Footnotes
The author reports the following potential conflicts of interest or sources of funding: M.L.-F. is a paid speaker for Sanofi, has received travel support from Serhosa/Zimmer, Grunenthal, and Exatech, and has received equipment, materials, drugs, medical writing, or other services from Smith & Nephew. Full ICMJE author disclosure forms are available for this article online, as supplementary material.
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