Abstract
The aim of this study was to determine if microfractures improve the outcome of high tibial osteotomy in patients with medial compartmental osteoarthritis in genu varum. Forty patients presenting with Outerbridge grade III and IV chondropathies on the femoral and/or the tibial joint surface underwent high tibial osteotomy with Puddu plates (Arthrex, Inc, Naples, Florida) for primary medial compartment osteoarthritis in genu varum at our institution. Patients were randomly assigned to either the high tibial osteotomy plus microfractures group (A; n=20) or the high tibial osteotomy alone group (B; n=20). Final assessment was conducted 5 years postoperatively, including clinical response measured by the International Knee Documentation Committee (IKDC), Lysholm score, and patient satisfaction score. All patients were blinded to the treatment received and followed the same rehabilitation protocol. A statistically significant improvement between pre- and postoperative values was observed for Lysholm and IKDC scores in both groups, without any statistically significant difference between them. Regarding the satisfaction score, there were no differences between the 2 groups in terms of preoperative self-assessment ( P>.05), whereas postoperative subjective satisfaction at 5-year follow-up was significantly higher in group A than in group B ( P=.0036).
Our study results provide further evidence that medial tibial osteotomy is an effective surgical option for treating a varus knee associated with medial degenerative arthritis in patients wishing to continue accustomed levels of physical activity. In particular, patient satisfaction was higher among those who underwent the combined treatment involving high tibial osteotomy to correct femorotibial angle and microfractures.
Drs Pascale (Walter), Luraghi, Perico, and Pascale (Valerio) are from IRCCS Galeazzi Orthopaedic Institute, and Dr Pascale (Valerio) is also from Clinica Ortopedica e Traumatologica, Università degli Studi di Milano, IRCCS Galeazzi Orthopaedic Institute, Milan, Italy.
Drs Pascale (Walter), Luraghi, Perico, and Pascale (Valerio) have no relevant financial relationships to disclose.
Correspondence should be addressed to: Walter Pascale, MD, IRCCS Galeazzi Orthopaedic Institute, Via R. Galeazzi 4, 20161 Milano, Italy (pascalew@tiscali.it).Treatment of unicompartmental knee osteoarthritis continues to raise discussion. As initially described by Jackson et al, 1 the causes of knee joint cartilage degeneration have been primarily attributed to medial deviation of the functional axis of the knee, tibial and femoral bone deformities, and malalignment and disorientation due to primary laxity of the collateral ligaments. 2 High tibial osteotomy is a treatment of choice, particularly in patients wishing to continue to practice high levels of physical activity. Unicompartmental prosthesis is a more definitive treatment than high tibial osteotomy and is indicated in patients affected by wider cartilage degeneration or in older patients. 3
First described by Jackson and Waugh 4 in 1982, high tibial osteotomy attracted attention following publication of long-term results in a study by Coventry et al. 5 Debeyre and Artigou 6 outlined the technique of open wedge medial tibial osteotomy. With the introduction of the Puddu plate (Arthrex, Inc, Naples, Florida) into clinical practice in the late 1990s, which simplified the technique, high tibial osteotomy has reached wider acceptance. However, controversy exists about the use of high tibial osteotomy in association with microfractures to stimulate cartilage regeneration. 7,8
Johnson 9 reported that microfracture is a suitable treatment for knee cartilage lesions, providing repair of the lesions by the formation of fibrocartilage. Although favorable results have been reported in patients with slight deviation of the functional axis, the long-term outcome remains unclear. 10,11 In their studies, Bergenudd et al 12 and Odenbring et al 13 found that high tibial osteotomy can lead to long-term clinical improvement in cases of knee cartilage lesions.
The aim of this study was to assess patient satisfaction and functional outcome after high tibial osteotomy in combination with microfractures in patients with medial osteoarthritis in genu varum.
Materials and Methods
The study population comprised 40 patients who underwent high tibial osteotomy with Puddu plates for primary medial compartment osteoarthritis in genu varum at our institution between 2002 and 2003. Inclusion criteria were chondropathies present on the femoral and/or the tibial joint surface, multiple Outerbridge grade III and IV lesions, femorotibial deviation between 7° and 10°, age between 40 and 70 years, body mass index (BMI) <32 kg/m 2. The work was approved by our institution’s ethical committee. All patients gave their consent to be included in the study.
Group A patients were treated with high tibial osteotomy plus microfractures (20 knees in 20 patients), while group B patients received high tibial osteotomy alone (20 knees in 20 patients). All 40 patients were randomly assigned to either group by an external researcher not involved in the study using a randomization block. All procedures were performed by the same surgeon (W.P.), and the patients were blinded to treatment received. Imaging studies, including anteroposterior (AP), lateral, and tangential knee and long-leg radiographs and magnetic resonance imaging (MRI) were performed for each patient (Figure ). The radiologist also was blinded to the study conditions. The patients received a 30-day course of prophylactic deep venous thrombosis treatment and a short-term course of prophylactic antibiotic therapy.
 | Figure 1:. AP radiograph of a high tibial osteotomy procedure. |
Knee joint cartilage was evaluated arthroscopically by the same surgeon preoperatively according to Outerbridge’s criteria: grade 0=normal; grade I=softening and slight fibrillation of the surface; grade II=generally smooth joint surface but with unevenness, fragmentation, fissuring, and fibrillation over an area <1.5 cm; grade III=white fibrous tissue, fragmentation, fissuring, and fibrillation over an area >1.5 cm; grade IV=subchondral bone exposure and eburnation over almost all the joint surface. 14
Symptoms were evaluated by the International Knee Documentation Committee (IKDC) and Lysholm scales preoperatively and at 6 months, 1 year, 2 years, and 5 years postoperatively. This study presents the 5-year follow-up data. Lysholm scores were considered: >64=not sufficient; 65–83=sufficient; 84–94=good; 95–100=excellent. Patient satisfaction was measured according to a satisfaction scale (score 1–10).
Surgical Technique
High tibial osteotomy was performed by wedge interlocking osteotomy and fixation with a Puddu plate. Prior to osteotomy, the degree of joint degeneration was measured arthroscopically. In group A, abrasion arthroplasty was performed using a steel abrader to a depth of approximately 1 mm; microfractures were created by drilling holes in the perimeter and the central area of the damaged cartilage to a depth of approximately 1 mm until bleeding of the subchondral bone occurred. This procedure was performed on the tibial plateau and femoral condyle in all patients except for 3 patients in group A who did not present with chondropathy of the tibial plateau and who received microfractures of the femoral condyle only. Group B patients underwent high tibial osteotomy only.
Starting from postoperative day 2, the physiotherapy regimen comprised physiotherapist-assisted continuous passive motion exercises, approximately 4 hours daily for 2 weeks, as well as isometric gymnastic and passive and active kinesis for approximately 2 hours daily for 2 weeks (Figure ). 15,16 The work load was adjusted at 6 to 8 weeks, before full weight bearing was permitted.
 | Figure 2:. After 2 weeks of the rehabilitation program, patients were able to actively reach 90° of flexion. |
Analysis of variance (ANOVA) was performed on continuous data; the chi-square test was used to analyze the categorical scores. Statistical significance was set at P<.05.
Using an alpha value of 0.05 and a power of 80%, the power calculations were derived from an estimated difference of 8 points in postoperative Lysholm score between the 2 groups. The sample size resulted in 20 patients for each group.
Results
The clinical characteristics of the patients are summarized in Table . Group A comprised 13 men and 7 women, and group B comprised 15 men and 5 women. Average patient age at surgery was 50±4.6 years (range, 44–64 years) in group A and 49.7±5.8 years (range, 43–67 years) in group B ( P<.05).
 | Table 1. Patient Clinical Characteristics |
Eleven patients in group A and 13 patients in group B were affected by Outer-bridge grade III lesions, whereas all other patients, 9 in group A and 7 in group B, presented with grade IV cartilage lesions. All patients presented with femoral and tibial eburnation, with the exception of 3 patients in group A and 2 patients in group B who did not have tibial eburnation. Three patients in group A and 2 in group B had received arthroscopic debridement; the remaining patients, 17 in group A and 18 in group B, had undergone conservative treatment for 1 year. All patients were affected by multiple lesions, differing in size and in Outerbridge grade, but no cases involved the entire tibial plateau or condyle. A significant difference between pre- and postoperative values in terms of femorotibial angle correction was present in each group (178.5±1.5 and 184.5±0.9 for group A, respectively; 178.2±1.6 and184.6±0.9 for group B, respectively; all P<.05), but no statistically significant differences between the 2 groups were observed (P<.05).
The same trend was observed for the Lysholm and IKDC scores preoperatively and 5 years postoperatively: analysis showed a statistically significant improvement in postoperative Lysholm scores in both groups compared to the preoperative scores ( P<.05), but there was no statistically significant difference in pre- and postoperative scores between the 2 groups ( P>.05) (Table ). Preoperative IKDC score was D in 70% and 75% of patients in group A and B, respectively ( P>.05). Postoperative IKDC score significantly increased in both groups: 16 patients in the combined treatment group (80%) and 17 patients treated with high tibial osteotomy alone (85%) scored A, whereas the others scored B, with no significant differences between the 2 groups ( P>.05).
 | Table 2. Mean Pre- and Postoperative Lysholm and Satisfaction Scores |
Regarding the satisfaction score, there were no differences between the 2 groups in terms of preoperative self-assessment ( P>.05), whereas postoperative subjective satisfaction at 5-year follow-up was significantly higher in group A than in group B ( P=.0036). The inverse correlation between BMI and postoperative Lysholm score ( r=-0.049; P=.001) was statistically significant only in group B patients. Furthermore, a negative correlation emerged between age and lesion grade according to Outerbridge’s criteria in group B patients: with increasing age, the lesion grade decreased (grades III and IV at an average age of 51.8 and 46.9 years, respectively; P=.014).
Postoperative Lysholm score was sufficient in 65% and good in 35% of group A patients, whereas in group B it was insufficient in 5%, sufficient in 60%, and good in 35% of patients. The patients who scored highest on the Lysholm scale were those with the highest preoperative lesion grade.
Magnetic resonance imaging assessment 5 years postoperatively disclosed regeneration of cartilage tissue on the femoral and tibial bones. In 3 cases of residual pain and articular stiffness in the operated knee, an arthroscopic second look of the joint observed good formation of a covering tissue (Figure ).
 | Figure 3:. Arthroscopic second look after 1 year with microfracture treatment of a medial femoral condyle. |
At 1-year follow-up, 1 patient was excluded from the study because of failure to return for examination. At 5-year follow-up, 2 patients (5%) were noted to have 3° undercorrection in genu varum that produced arthroscopically and clinically insufficient healing. For this reason and because of persistent pain, both received total knee arthroplasty (TKA). Deep venous thrombosis in 1 patient (2.5%) resolved with medical and compression therapy and did not affect the final analysis of the results.
Discussion
Our study results provide further evidence that medial tibial osteotomy is an effective surgical option for treating a varus knee associated with medial degenerative arthritis in patients wishing to continue accustomed levels of physical activity. In particular, patient satisfaction was higher among those who underwent the combined treatment involving high tibial osteotomy to correct femorotibial angle and microfractures. Furthermore, an inverse correlation emerged between BMI values, Lysholm and IKDC scores, patient age, and degree of correction.
In this study population, a second intervention was necessary in only 2 cases where correction of the mechanical axis failed to restore normal valgus and serious pain persisted at 5-year follow-up. The 2 patients subsequently underwent TKA.
Published data suggest that abrasion-microfractures fail to completely resolve knee joint damage in patients with medial compartment arthritis associated with severe genu varum. 17–19 Indeed, symptoms may later return, even after initial good results at 1-year postoperatively. For this reason, as described by Shaw and Moulton, 20 high tibial osteotomy associated with microfractures is a valid attempt to correct the primary cause of arthritis. As demonstrated in a study by Puddu et al, 21 medial tibial osteotomy is able to produce a clear improvement in clinical and subjective symptoms. Given the subjective nature of pain symptoms, our results show that the combined treatment achieved greater postoperative patient satisfaction, although the clinical results in the 2 treatment groups were objectively definitely comparable. This was probably due to the fibrocartilage formation that abrasion and microfracture are able to promote by stimulating the incoming of subchondral bone marrow blood to the surgical site. Fibrocartilage formation leads to enhanced restoration of physiological knee joint equilibrium, thus reducing pain and increasing patient satisfaction.
Six years postoperatively, we performed arthroscopic reintervention for a medial meniscal lesion in 3 patients. In these patients we were able to observe the new regenerated cartilaginous tissue on the area treated by microfractures. In 2 of these patients, the new formed tissue completely covered the chondral lesion, both approximately 1 cm 2, at femoral condyle level in 1 case and on the tibial plateau in the other. In the third patient, where the lesion size was approximately 3 cm 2, the new regenerated cartilaginous tissue just partially covered the tibial area. However, despite the results obtained by the second look arthroscopy in 3 of our patients showing no differences between condyles and tibial plateau, our surgical experience allowed us to observe that normally the use of microfractures in combination with osteotomy yields better subjective results in the femoral condyle than in the tibial plateau.
Even if it is known that chondral lesions microfractures could not result in exhaustive and durable results, in particular in lesions >1 cm 2, this technique is still the most used treatment for isolated cartilage lesions. When patients present an axial deviation, the outcome could ameliorate combining microfractures with high tibial osteotomy. However, when high tibial osteotomy is not practical, as in normal morphotype patients, alternative treatments could be used for larger cartilage lesions according to patient age, activity level, and general joint conditions. 22 This evidence induced us to use microfractures in patients with focal chondral lesions, whereas for larger lesions, and in cases of correct indications, we performed high tibial osteotomy or a uniprosthesis.
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