|Year : 2020 | Volume
| Issue : 2 | Page : 97-105
Arthroscopic treatment of chondral lesions in varus knee in adults combined with corrective high tibial osteotomy
Wael Shaban, Eslam Hussein, Hassan El Behairy, Mohammed Yehia
Department of Orthopedic Surgery, Faculty of Medicine for Girls, Al-Azhar University, Cairo, Egypt
|Date of Submission||02-Jan-2020|
|Date of Decision||16-Jan-2020|
|Date of Acceptance||20-Jan-2020|
|Date of Web Publication||29-Jun-2020|
Dr. Wael Shaban
MD, Assistant Professor of Orthopedic Surgery, 15, Mohamed Refat St, Abassia, Cairo
Source of Support: None, Conflict of Interest: None
Objectives To document whether cartilage regeneration occurs in the degenerated medial compartment of arthritic knees in patients with varus malalignment after medial opening wedge high tibial osteotomy (MOWHTO) with concomitant cartilage procedures and to assess which predictive factors influence the clinical outcome.
Patients and methods A total of 28 patients underwent MOWHTO between December 2016 and December 2018 in Al-Zahraa University Hospital for varus malalignment and medial osteoarthritis. Preoperative and postoperative assessments were done using American Knee Society’s Knee and Functional Scoring System. All patients were evaluated by arthroscopy before and ∼12 months after HTO. The International Cartilage Repair Society grading system was used for arthroscopic grading.
Results At initial arthroscopy, two (7.1%) knees had grade II medial femoral condyle articular cartilage finding, seven (25%) knees had grade III findings, and 19 (67.9%) knees had grade IV findings. Only 20 cases had second-look arthroscopy, no regenerative change was found in 40% of knees, white scattering fibrocartilage was found in 55% of knees, and deterioration of the cartilage was observed in one (5%) case.
Conclusion The degenerated cartilage could be partially or entirely covered by newly regenerated cartilage at 1 years after adequate correction of varus deformity by MOWHTO.
Keywords: articular cartilage, high tibial osteotomy, opening wedge, osteoarthritis
|How to cite this article:|
Shaban W, Hussein E, El Behairy H, Yehia M. Arthroscopic treatment of chondral lesions in varus knee in adults combined with corrective high tibial osteotomy. Sci J Al-Azhar Med Fac Girls 2020;4:97-105
|How to cite this URL:|
Shaban W, Hussein E, El Behairy H, Yehia M. Arthroscopic treatment of chondral lesions in varus knee in adults combined with corrective high tibial osteotomy. Sci J Al-Azhar Med Fac Girls [serial online] 2020 [cited 2020 Jul 11];4:97-105. Available from: http://www.sjamf.eg.net/text.asp?2020/4/2/97/288258
| Introduction|| |
Varus deformity with unicompartmental arthritis can be symptomatically improved by corrective osteotomy. This is believed to be due to transferring the weight-bearing forces from the diseased compartment to the less involved one, so the pressure decreases and degeneration of the overloaded compartment may slow or reverse . Pauwels  showed that a previously narrowed joint space will widen postoperatively, and both subchondral cysts and sclerosis will regress. This study concerns the second-look arthroscopic assessment of cartilage regeneration after medial opening wedge high tibial osteotomy (MOWHTO).
The surgical technique underwent many variations in the fixation technique. The advantages of MOWHTO over the closed wedge procedure include the maintenance of bone stock and correction of deformities close to their origins in the proximal tibia without the need for a fibular osteotomy . The disadvantages of closed wedge HTO are danger of peroneal nerve injury, fibular osteotomy, difficulty in acquiring the correction angle, sagittal plane imbalance, and medial collateral ligament insufficiency .
| Patients and methods|| |
This study was a prospective one that consisted of 28 knees in 28 patients who underwent MOWHTO between December 2016 and December 2018 in Al-Zahraa University Hospital. Patients consent is taken from all patients as regarding all the information about the surgical procedure, including the benefits and risks. There were 15 women and 13 men, with a mean age of 36.9±6 years (range, 25–45 years). Follow-up ranged approximately from 7 to 15 months after surgery, with a mean of 9.5±2.2 months.
Inclusion criteria were varus malalignment of the limb that could be corrected by a plate requiring less than 16° correction associated with osteoarthritis and pain limited to the medial side of the knee, lateral joint compartment was intact or its cartilage lesions had an International Cartilage Repair Society grade of less than 1, absence of knee contracture, with or without ligamentous instability, and BMI less than 30 kg/m2. There were no age restrictions, and the preferred age was less than 50 years.
Exclusion criteria were combined medial and lateral arthrosis, flexion contracture more than 20°, lack of flexion beyond 80°, and instability allowing the tibia to subluxate more than 1 cm. The presence of patellofemoral arthrosis was not considered an absolute contraindication.
All patients were evaluated using the American Knee Society’s knee and Functional Scoring System (KSS) . It assesses pain, range of motion, and stability. It offers deductions for flexion contractures, extension lag, and angles of varus malalignment. Pain is typically localized to medial compartment early in disease process, whereas in long-standing osteoarthritis, pain becomes diffuse. Mechanical symptoms of intermittent catching or locking suggest articular irregularity or meniscal abnormality.
A full-length standing radiograph was used. We defined the point at the medial edge of the tibial condyle as 0% and the point at the lateral edge as 100%. HTO is carried to pass the mechanical axis at point 62%. According to Noyes et al. , a line is drawn from center of femoral head to point 62% of the tibial width ([Figure 1]a). A second line is drawn from center of ankle to the 62% coordinate. The angle between these two lines is the correction angle ,. On the lateral radiograph, the posterior tibial slope (PTS) is measured according to Brazier method ([Figure 1]b); it is the angle formed by the tangent to the medial tibial plateau and the line perpendicular to the tangent at the posterior tibial cortex .
|Figure 1 (a) The correction angle. (b) PTS measurement. PTS, posterior tibial slope.|
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Regarding arthroscopy, all patients received an arthroscopic examination at the time of HTO including assessments of the patellofemoral joint and the medial and the lateral compartments. If grade III or IV changes were seen in the lateral compartment, we did not perform the osteotomy, and if grade II changes were present, we still performed an osteotomy but did not overcorrect beyond neutral, as we might introduce chondral changes in the lateral compartment. Another intra-articular concomitant pathology was treated such as irrigation of joint debris or meniscectomy of a flap tear. Cartilage procedures may be carried out such as microfracture.
Regarding incision, 3-mm K-wires are advanced medially from 1 cm distal and parallel to joint line to the lateral cortex to ensure maintenance of the original PTS and prevent extension of the fracture to the tibial plateau ([Figure 2]a). Skin incision of 3–6 cm anteromedially was done midway between the tibial tubercle and posteromedial tibial cortex, beginning 1 cm inferior to the joint line and extending distally. The sartorius fascia is sharply divided superior to the gracilis tendon taking care not to penetrate the underlying superficial medial collateral ligament to expose the tendons of gracilis and semitendinosus, which retracted posteriorly ([Figure 2]b). Superficial medial collateral ligament was dissected from the bone. There was no risk of instability because the deepest and much more stabilizing tibio-meniscal bundle of the ligament remains intact. A blunt retractor is placed deep to the collateral ligament to prevent damage to the neurovascular structures. The superior attachment of the patellar tendon was recessed 5 mm using a scalpel for adequate exposure for the osteotomy.
|Figure 2 Placement of the incision. Incision landmarks and K-wire insertion.|
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Osteotomy: 2-mm K-wires were obliquely oriented starting 4 cm below joint line and directed across the superior aspect of the tibial tubercle to 1 cm below the lateral joint line to retain a possible width of the lateral tibial plateau. An oscillating saw was used to cut the medial cortex only and then sharp osteotomes are used ([Figure 3]a and b). To avoid intra-articular damage, the osteotomy was carefully exposed by the stepwise insertion of three coupled osteotomes. In case of biplanar osteotomy, only the posterior two-thirds of the tibia is cut. The ascending cut is performed 2 cm behind the tibial tuberosity at 110° to horizontal oblique osteotomy ([Figure 3]c). The osteotomy was carried to within 10 mm of the lateral cortex. The posterior cortex should be checked completely by osteotome; this is important, otherwise the opening will be greater anteriorly increasing the PTS. The osteotomy is opened gradually using a laminar spreader ([Figure 3]d). To maintain the PTS, it is of most importance at this moment to obtain full extension, and the foot should be supported not to be lodged at the table. This will ensure trapezoidal gap opening rather than rectangular in the sagittal plane, such that the anterior gap was half of the posterior gap. The posterolateral location of the cortical hinge would increase PTS, and the lateral location of the cortical hinge will not affect the PTS ([Figure 4]) .
Regarding plate fixation, 18 cases were fixed with a locking Tomofix plate and 10 with a nonlocking Puddu or EL-Assal Plate. The Tomofix device has eight locking bolts, comprising four proximal and four distal. An additional lag screw is applied at first distal hole below osteotomy after proximal fixation, inducing compression on the lateral hinge, eliminating any distraction or instability in this area ([Figure 5],[Figure 6],[Figure 7],[Figure 8]).
|Figure 5 The Tomofix plate. A lag screw is (green arrow) inserted causing a force vector upward (red arrows) with lateral hinge-point compression (blue arrows).|
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|Figure 6 Case no.1: a 30-year-old female patient. Serial radiographs at 1 month (a) and 5 months (b) postoperatively with slight increase of the PTS. Grade IV degeneration of the medial femoral condyle at the time of HTO (c). Second-look arthroscopy at 12 weeks shows some coverage with fibrous cartilage (d). HTO, high tibial osteotomy; PTS, posterior tibial slope.|
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|Figure 7 Case no.2: a 27-year-old male patient. Sequence of osteotomy gap healing at 1 and 5 months after surgery. (a) Grade IV chondral degeneration of the medial femoral condyle at the time of HTO. (b) Second-look arthroscopy at 12 weeks shows no change. HTO, high tibial osteotomy.|
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|Figure 8 Case no.3: a 30-year-old female patient with left genu varum. Sequence of osteotomy gap healing at 1 month (a) and 3 months (b) after surgery with slight increase of the PTS. Grade IV degeneration of the medial femoral condyle at the time of HTO (c). Second-look arthroscopy at 12 weeks shows some coverage with fibrous cartilage (d). HTO, high tibial osteotomy; PTS, posterior tibial slope.|
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For effective decompression of medial compartment, a complete release of the distal fibers of medial collateral ligament is necessary after osteotomy.
Postoperative follow-up program
Immediately after the operation, the patient is put in a hinged knee brace. Prophylaxis for DVT is by low-molecular-weight heparin 5000 U subcutaneously every 24 h for one week and then aspirin for 6 weeks. Isometric quadriceps and ankle exercises using continuous passive motion apparatus were begun after surgery. Patients were allowed to move the knee from 0 to 110° within the second week postoperatively, with flexion gradually increased to 135° by the fourth postoperative week. The amount of initial weight bearing depends strongly on the type of fixation used; partial weight-bearing was allowed at sixth weeks, and full weight-bearing at 12th weeks. It can be begun earlier with the use of locked Tomofix plate. Serial radiograph was done every 3 weeks. Second-look arthroscopy was done after 1 year.
| Results|| |
The mean preoperative KSS score was 85.2±8.8 (range, 66–97) and postoperative KSS score was 94.9±6.5 (range, 66–100). The mean KSS improved significantly after operation, with paired difference of 9.73 using paired sample t test, with P value less than 0.05, and this is a good result ([Table 1]).
|Table 1 Statistically significant difference between preoperative and postoperative according knee score, using paired sample t test, with P value less than 0.05, significant|
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Insertion of bone graft was applied to five (17.9%) patients as the osteotomy gap was wider. Number of requests of rescue analgesia by patients with grafts was significantly (P=0.002) higher compared with patients without grafts. Moreover, patients with grafts had significantly (P=0.001) longer postoperative hospital stay for a mean duration of 69±6 h (range, 60–72 h). The remaining 23 patients were discharged after a mean hospital stay of 50±5.8 h (range, 48–72 h), for a mean duration of hospital stay of 52.7±8.8 h (range, 48–72 h) for total studied patients ([Table 2]).
The increase in the slope in the MOWHTO was statistically significant between before and 3 months after operation (P=0.013). Radiological union was complete after 20.5±4.4 weeks in 18 (64.3%) knees, 23±0.9 weeks in six (21.4%) knees, 30±2.8 weeks in two (7.1%) knees and 34.5±2.1 weeks in the remaining two (7.1%) knees for a mean time till complete union of 22.7±4.4 weeks for all of the knees operated upon. Two (7.1%) patients had delayed union, which resolved by 7–9 months, postoperatively. Full weight bearing was achieved at a mean of 6.23±0.62 weeks (range, 6–8 weeks), postoperatively. Two (7.1%) patients had delayed union, which resolved by 7–9 months, postoperatively. Hinged knee brace used postoperative for 3 months was applied to two patients with fracture lateral cortex, and they united well.
The mean preoperative femorotibial angle was 13.43° in varus malalignment (range, 10–16° varus). 14 knees had full correction to neutral axis. 10 knee with overcorrection (mean was 1.63° valgus). undercorrection observed in four patients who had residual varus deformity(mean was 1.54° varus). The mean preoperative proximal medial tibial angle was 82° (range, 77–84), whereas the mean postoperative angle was 89° (range, 87–92). One patient developed wound infection, and prominent hardware was managed by implant removal.
At initial arthroscopy, degeneration was graded according to the International Cartilage Repair Society system: superficial lesions are considered grade I cartilage defects, whereas lesions extending down to less than 50% cartilage depth are considered grade II, which was found in two (7.1%) knees. Lesions extending down to more than 50% were considered grade III, which was found in seven (25%) knees. Lesions involving the subchondral bone are classified as grade IV, which was found in 19 (67.9%) knees.
Only 20 cases underwent second-look arthroscopic examination. This evaluation was not performed in the eight cases that were lost to follow-up. For evaluation of cartilage regeneration, the articular cartilage was classified according to regeneration and maturation grade  into two grades, as no regenerative change (grade I) or white scattering with fibrocartilage (grade II). Grade I (no regenerative change) was found in 40% of knees (eight knees), and grade II (white scattering fibrocartilage) was found in 55% of knees (11 knees); deterioration of the cartilage was observed in one (5%) knee.
| Discussion|| |
HTO is an effective procedure for the relief of pain and restoration of function in patients with medial osteoarthritis of the knee. It unloads the medial joint, decreases the medial tibial sclerosis, and improves the adduction moment about the knee during gait. The role of additional cartilage procedures along with HTO including arthroscopic debridement, drilling, shaving, and microfracture has been debated. Akizuki et al.  compared combined HTO and abrasion arthroplasty versus HTO alone and found no difference in clinical and histologic examinations between groups. Okahashi  suggested that improvement of the cartilage was confirmed. They reported that regenerated cartilage was hyaline-like cartilage in a few cases through histologic examination. A recent study  analyzed the effect of subchondral drilling among patients with HTO and found no difference in the formation of fibrocartilage with or without subchondral drilling.
Throughout our study, 46 patients were eligible for evaluation. Fifteen patients were excluded for having combined medial and lateral arthrosis (n=4), BMI of more than 30 kg/m2 (n=4), lack of flexion beyond 80° (n=3), joint instability (n=2), and patellofemoral arthrosis (two patients). Thirty-one patients were enrolled in the study; however, three patients were excluded after the arthroscopy for having grade IV changes in lateral compartment, and the remaining 28 patients continued the study. Degenerative cartilage was partially regenerated in almost all cases after MOWHTO; it was a thickened tissue that resembled fibrocartilage and was not hyaline cartilage with regard to hardness as judged by palpation with a probe. However, because of the lack of a control group in our study, the effect of chondral resurfacing procedures remains unclear.
Ideal postoperative alignment after HTO has been proven to have a significant influence on clinical outcome. Jung et al.  found that improvement is much more in cases with postoperative limb alignment (mechanical tibiofemoral angle >0° and valgus <6°) than in those with undercorrection (<0°) and overcorrection (valgus >6°). However, Tsukada and Wakui  found no significant differences between overcorrected and moderately corrected knees. In our study, the postoperative alignment influenced the clinical improvement as evidenced by KSS scores at a minimum of 1-year follow-up because of the effect of nonweight bearing and the biologic effect of osteotomy. However, we did not observe poor results in patients with undercorrection. We think that this result comes from the short follow-up period. Most of the patients are satisfied because of the decompressive effect on bone, and this effect alleviates pain in short term. It remains unclear whether overcorrected knees could obtain a higher ratio of cartilage repair than moderately corrected knees.
MOWHTO increases the PTS by ∼3–4°. This change in slope is stable over time, and there is no correlation between the amount of correction in the frontal plane and the degree change in the PTS. To minimize the change in PTS after HTO, Noyes et al.  advised that the opening gap at the tibial tuberosity should be approximately half of the gap at the posteromedial cortex. Hernigou et al.  emphasized that to minimize changes in PTS, it is necessary to place the plate as close as possible to the posteromedial corner. Our results are similar, but with smaller average increase.
Despite the routine addition of bone graft as a part of the HTO procedure, this study supports MOWHTO without bone graft, which shortens the operative time and avoids unnecessary donor site morbidity, and early weight-bearing can occur without an elevated risk of nonunion or loss of correction.
This study had some limitations. First is the need for longer follow-up. We need to determine if a combined MOWHTO and chondral resurfacing procedure will provide greater longevity in its ability to delay or eliminate the need for arthroplasty as compared with the longevity of patients treated with an osteotomy in isolation. There was a lack of a control group with MOWHTO alone; therefore, we cannot conclude how much of the improvement was due to the combined procedure versus just an osteotomy, although most patients improved. Second, the reasons for regeneration of degenerated articular cartilage after HTO were not identified. The histologic findings at second-look arthroscopy were not investigated. This study did not assess the use of GEMRIC technologies (gadolinium-enhanced magnetic resonance imaging of cartilage) and expression of fibrogenic cytokines in the synovium. Such methods of assessment would have improved the analysis of cartilage quality after HTO.
| Conclusion|| |
In conclusion, excessive pressure on the medial compartment of the osteoarthritic knee with a varus deformity can cause the articular cartilage to wear down and fragment. A MOWHTO can be stabilized with a plate and can be used to treat medial osteoarthritis with genu varum. The degenerated cartilage of the medial femoral condyle and medial tibial plateau could be partially covered by newly regenerated cartilage at 1 year after adequate correction of varus deformity. Although this study has some limitations, our results suggest that the degree of correction obtained with a MOWHTO correlates with both visible improvement in the articular surface and the clinical score.There are no conflicts of interest
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
[Table 1], [Table 2]