Background: Intra-articular injection of hyaluronic acid has become an intervention step between conservative and operative treatment of knee osteoarthritis. This is recommended by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR). However, the expected outcomes and the selection criteria are undetermined and controversial. A few articles have mentioned the long-term result of Sodium Hyaluronate in failed conservative treatment.
Objective: Determine the clinical outcomes of treatment with three intra-articular Sodium Hyaluronate injections (500-730 kilodalton (KDA), Hyalgan) in knee-osteoarthritis patients who failed conservative treatment.
Material and Method: This was an uncontrolled, retrospective-cohort study with at least a 24-month followup period. The outcomes of the treatment were evaluated by questionnaires and telephone calls. The primary efficacy parameter was the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score and the secondary efficacy parameter was delay or cancellation of any surgical treatments during the followup period. Patients who had undergone surgical treatments were placed in the non response group. The response group has repeated treatment every year.
Results: One hundred and eighty-three patients (208 knees) treated with intra-articular Sodium Hyaluronate were classified into three groups according to radiographic assessment. In group 1, narrowing joint space (Ahlback grade 1-2), WOMAC score improved from 70.46 to 26.55 (p < 0.0001), 41 in 46 patients (44/49 knees) did not require any surgical treatments. In group 2, bony attrition (Ahlback grade 3-4), WOMAC score improved from 70.19 to 40.38 (p < 0.0001), 47 in 70 patients (51/78 knees) did not require surgical treatment. In group 3, lateral subluxation (Ahlback grade5) WOMAC score improved from 64.71 to 32.67 (p < 0.0001), 58 in 67 patients (69/81knees) did not require surgical treatment. The result from WOMAC subscale analysis revealed an improvement in pain, stiffness, and function in all groups (p < 0.0001), but did not improve in ambulatory status.
Conclusion: Intra-articular Sodium Hyaluronate injection, used in knee-osteoarthritis patients who failed conservative treatment, was effective in visible cartilage patients (Ahlback grade1, 2) without mechanical problems involved. In severe osteoarthritis patients (Ahlback grade 3, 4, 5), this treatment was of less benefit if those patients were young, active, and expected independent ambulation. Surgical treatment may be a procedure of choice to meet patient expectation in improving function and ambulatory status. On the other hand, if patients were old and inactive with household ambulation, using intra-articular Sodium Hyaluronate was beneficial in improving pain, stiffness, and function but not ambulation level with 86.56% of excellent or good in overall satisfaction level. Thus, the radiographic evaluation, age, ambulatory status, and patient expectation may be the key factors to determine successful outcomes.

Keywords: Hyaluronic acid, Failed Conservative Treatment, Knee Osteoarthritis