In this study, patients who did not respond to conservative treatment achieved favorable outcomes following PRP injection and physiotherapy. The findings showed the efficacy of PRP injection as a non-operative treatment option for resistant isolated patellofemoral arthritis.
Anterior knee pain (AKP) is the most common reason adolescents, adults, and physically active individuals consult with a knee orthopedic surgeon. [20] AKP was thought to be caused by chondromalacia patellae until the late 1960s. Numerous authors, however, have been unable to link AKP and chondromalacia patellae conclusively. [21] In the 1970s, AKP was associated with patellofemoral malalignment (PFM), which was frequently treated surgically, with mixed results. [22] The tissue homeostasis theory was proposed in the 1990s by Scott F. Dye and his research group at the University of California, San Francisco. According to this theory, joints are not merely mechanical structures; they are living, metabolically active systems. Pain is caused by a mosaic of physio-pathological factors, including increased osseous remodeling, increased intraosseous pressure, and peripatellar synovitis, all of which result in a reduced "envelope of function" and pain. [23 24] According to Dye's envelope of load acceptance theory, overuse or cyclical overload of soft tissue or bone areas may account for AKP in a significant number of patients who do not have patellofemoral or limb malalignment. Hyperinnervation of the patellar lateral retinacula results in decreased susceptibility to stress and pain. [25] Additionally, stress cycles induce periodic ischemic states in the patellar cartilage. Selfe and colleagues classified AKP patients into three groups based on their oxygenation status: hypoxic, inflammatory, or mechanical. On the other hand, Ischemia may be the source of pain in all three groups, as inflammatory changes can occur not only following stress-induced cartilage ischemia but also following mechanical damage to the vascular system. [26]
These theories can be summarised as follows: abnormal PF joint alignment and trochlear morphology (patella alta and patellar tilt), kinetic and kinematic abnormalities (quadriceps muscle size, strength, and force), rupture and reconstruction of the ACL (anterior cruciate ligament), female gender, age, and body mass index have all been identified as risk factors for progression of PF cartilage deterioration by affecting the functional envelope. [27]
Strengthening and gait retraining is currently the primary stay of treatment for PFA. Additionally, in mild to moderate cases, non-operative measures such as cortisone injections, hyaluronic acid injections, orthobiologics such as platelet-rich plasma [PRP] or stem cell injections, and passive patellar maltracking correction using bracing and taping may be beneficial. Conservative measures are ineffective after 3–6 months, indicating the need for surgical intervention. [28]
PRP contains high concentrations of growth factors, which regulate chondral homeostasis and benefit both the healing and chondrogenesis processes. PRP stimulates the cellular proliferation and matrix synthesis of chondrocytes in vitro. By supplementing the culture medium with PRP, porcine chondrocytes and collagen and proteoglycan syntheses are increased. [29] PRP demonstrated a beneficial effect on cartilage repair and restoration following microfractures in animal and human studies. [30, 31] Moussa et al. demonstrated that PRP has a beneficial effect on chondrocytes, synovial, and stem mesenchymal cells by increasing cell proliferation, extracellular matrix production, and hyaluronic acid syntheses; PRP can also act as a bioactive scaffold in cartilage defects. 32
Meta-analyses of numerous randomized trials have supported the efficacy of PRP intra-articular knee injection in treating tibiofemoral OA. [11, 12, 33–38] However, treating patellofemoral arthritis with intra-articular injections has been linked to a worse outcome. [39]. On the other hand, some studies yielded positive results. [13–16]
The GPS III Platelet Concentration System was used to prepare the PRP, and injection was performed using the buffy coat layer. The composition of this layer was analyzed and found to contain increased platelet concentrations (3-6 times that of the patient's baseline), as well as increased white blood cell concentrations (3-6 times that of the patient's baseline); these included neutrophils, leukocytes, and monocytes, and was dubbed leukocyte-rich platelet-rich plasma (LR-PRP). White blood cells may participate in modulating inflammatory and platelet activation, thereby enhancing the tissue repair mechanism. [40] Zimmermann et al. discovered that an increase in white blood cell count explained between one-third and half of the variation in growth factors observed in their samples. They discovered a positive correlation between the white blood cell count and VEGF levels (a protein known to be produced by white blood cells) and PDGF. [41]
In this study, patients with isolated PRP who do not respond to initial conservative management may benefit from a single well-prepared PRP injection that lasts at least one year. This management mode may benefit this patient population and may result in a delay or cessation of surgical treatment. We found no adverse events associated with the use of PRP injections. Rai and Singh reported that 9 (9.18 percent) of their patients experienced headache, dizziness, sweating, and syncope for approximately 20 to 30 minutes following intra-articular PRP injection.[42] Patel hypothesized that the adverse effects of PRP were caused by the higher CaCl2 concentration used to prepare the sample. [43]
The study's limitations include small sample size, an observational design with no intention of randomization, and a brief follow-up period. We recommend additional research to address all of these limitations. However, the study has some strong points, such as the presence of a control group and the strict selection of patients to allow for a more thorough analysis of the outcomes.