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Purpose: This study documented the healing potential of degenerated articular cartilage after opening-wedge valgus high tibial osteotomy (HTO) in patients with osteoarthritis of the knee. It was hypothesized that regeneration of articular cartilage is affected by several factors, including preoperative cartilage degeneration grade, difference between the medial femoral condyle (MFC) and the medial tibial condyle (MTC), and postoperative knee alignment., Methods: Medial opening-wedge valgus HTO was performed in 131 knees of 100 patients (mean age 66 ± 7.7 years). Initial arthroscopy was performed at the time of HTO, and a second-look arthroscopy was performed at the time of plate removal (20.8 ± 6.5 months after HTO). Status of articular cartilage was assessed according to the ICRS grade. Cartilage regeneration was also evaluated by the presence of newly formed cartilaginous tissue. All subjects were followed up postoperatively at 2 years for assessment of clinical and radiographic outcomes., Results: The number of subjects in ICRS grade 1/2/3/4 was significantly altered from 0/11/53/67 preoperatively to 14/21/56/40 postoperatively in the MFC (P < 0.05) and 0/12/62/57 preoperatively to 9/24/64/34 postoperatively in the MTC (P < 0.05). Newly formed cartilaginous tissue was found in 71 % of MFCs and 51 % of MTCs. Incidence of cartilage regeneration was significantly higher in lower BMI cases, MFC, preoperatively advanced ICRS grade and overcorrected knees. Age, gender and clinical outcomes did not affect cartilage regeneration., Conclusion: Cartilage regeneration in degenerated articular cartilage is induced after opening-wedge valgus HTO, which is affected by BMI, the difference between the MFC and MTC, preoperative cartilage degeneration grade, and postoperative limb alignment. Therefore, patient selection by BMI rather than age, and surgical techniques maintaining valgus knee alignment should be considered for cartilage regeneration., Level of Evidence: Level IV, therapeutic case series.

It has been predicted that significant stress will be applied to the plate and lateral cortical hinge of an osteotomy site when early full weight bearing is commenced after an open wedge high tibial osteotomy. We hypothesized that the stress concentration on the plate or at the lateral cortical hinge would be reduced by inserting bone substitutes into the osteotomy gap. Two different types of tibia model were investigated: Group A, fixation with TomoFix with the osteotomy site left as an open space; and Group B, two beta-TCP wedges are inserted into osteotomy site and fixed with TomoFix. Stress at five points was measured using strain gauges. Specimens were mounted onto a testing machine with an FTA (femoro-tibial angle) of 170 degrees . Cyclic load tests and an ultimate load test were then performed. The mean stress on the plate was measured at 15.5+/-1.8Mpa in Group A. On the other hand, this value in Group B was only 9.52+/-2.1Mpa and this was a significant difference (P<0.01). The mean stress on the lateral hinge in Groups A and B was 3.31+/-0.5 and 2.49+/-0.2, respectively which was also a significant difference (P<0.05). The mean maximum breaking load in Group A was 2500+/-280N and in Group B 4270+/-420N which was a significant difference (P<0.01). Hence, for OWHTO procedures, the use of beta-TCP wedges and TomoFix is thus likely to improve the initial axial and possibly rotational stability at the osteotomy site in comparison with methods that leave the osteotomy gap open.

Since 1969 corrective osteotomy has been performed at our institute in young patients (under 40 years) with bowlegs, knock knees and flexion or rotational deformities around the knee. Fifty-seven knees (29 left, 28 right) of 45 patients (19 boys, 26 girls) were followed-up for a period ranging from 30 to 38 years in seven patients with seven knees, from 20 to 29 years in nine patients with 11 knees, and from ten to 19 years in 29 patients with 39 knees. Supracondylar femoral osteotomy was performed on 12 knees (11 patients), high tibial osteotomy above the tibial tuberosity on eight knees (six patients) and below the tuberosity on 37 knees (28 patients). At the final follow-up (age range 42-73 years), all of the deformities were satisfactorily corrected, with no symptoms apart from nine knees, seven of which had dull pain after strenuous sport with osteophytes, etc. in the radiograph. Total knee arthroplasty was performed in the remaining two knees, at ten and 26 years, respectively, after the initial osteotomy. Osteoarthritis developed in the contralateral knee to the initial osteotomy in two patients after 34 years at age 73 and after 33 years at age 67.

The treatment of patients with osteoarthritic knees accompanied by ipsilateral osteoarthritic ankles is not well documented. We here report both clinical results and radiographic evaluations of such patients treated using a high tibial osteotomy (HTO). HTO was performed on 16 knees of 10 patients (all women with a mean age; 68 years; range 58 to 73 years) who had a varus deformity of both their legs as a result of medial compartmental osteoarthritis of their knees. The Hospital for Special Surgery's (HSS score) knee scoring system and the clinical rating system for the ankle-hindfoot by Kitaoka (AOFAS) were used to evaluate the patients clinically before and after HTO. Radiographic findings were measured using antero-posterior one-leg weight bearing radiographs of the whole lower extremity taken before surgery. The mean time of follow-up was 8 years (range, 4-10 years). The HSS score improved from 54 to 91 points after HTO and the mean ankle score improved significantly from 54 to 86 points. After HTO also, the alignment of the knees changed from 6 degrees varus to 12 degrees valgus. The decrease of the inclination angle of the tibial axis changed from 10 degrees laterally to - 2 degrees medially and the talar tilt angle improved from 18 degrees to 6 degrees resulting in an improvement of the ankle congruity. HTO, which can correct the total alignment of the lower extremity, is thus recommended as one of more effective surgical procedures for patients with an ipsilateral osteoarthritis of the knee and ankle.

A long-term follow-up study was performed on 75 knees of 53 patients after high tibial valgus osteotomy. The earlier results have previously been reported. There were 15 knees in 11 men and 60 knees in 42 women. The follow-up period ranged from 15 to 28 years with a mean of 19 +/- 3 years. The age at osteotomy ranged from 46 to 73 years with a mean of 59.6 +/- 6.7 years. The diagnosis was medial compartmental osteoarthritis (OA) in 68 knees (46 patients) and spontaneous osteonecrosis of the medial femoral condyle in 7 knees (7 patients). Valgus osteotomy was performed above the tibial tuberosity, with removal of a laterally based wedge in all cases, aiming for anatomical valgus angulation of 10 degrees . The American Knee Society Score showed a Knee Score of 37 +/- 20 and a Function Score of 38 +/- 16 preoperatively and 87 +/- 13 and 80 +/- 19 at the final 15 to 28 years' follow-up. The femoro-tibial angle in standing was 186 +/- 6.5 degrees (6 degrees of anatomical varus angulation) before and 171 +/- 7.5 degrees (9 degrees of anatomical valgus angulation) at final follow-up (p < 0.0001), with no apparent loss of limb alignment.

The aim of the current study was to document regeneration of the articular cartilage after correction of varus deformity for osteoarthritis of the knee. The repair of articular cartilage after high tibial valgus osteotomy for medial compartmental osteoarthritis was observed in 146 knees of 115 patients. The mean age of the patients at osteotomy was 65+/-7 years (range 47-80). Observations were made through an arthrotomy at the time of removal of the blade plate, an average of 2 years after the initial osteotomy. Regeneration of the degenerated cartilage was classified into three stages. There were no regenerative findings (Stage A) in 13 knees; partial regeneration with fibrocartilaginous tissue (Stage B) in the previous degenerated area (Stage B) in 86 knees; and total coverage by new regenerated fibrocartilage or hyaline-like cartilage (Stage C) in 47 knees. Mature regeneration (Stage C) was observed more frequently in the knees with increased width of the medial joint space after high tibial osteotomy than in those with unchanged width (P<0.01), and in the knees with more than 5 degrees of anatomical valgus angulation after osteotomy than in those with less than 5 degrees (P=0.05). Even the knees with eburnation of subchondral bone in the weight-bearing portion showed Stage C regeneration in 26 out of 80, in contrast with no regeneration in two knees with degenerated cartilage remaining. O'Driscoll's histological and histochemical grading score was higher in the Stage C group (P<0.02). The weight-bearing portion of the medial femoral condyle with exposed bone was concluded to be partially or entirely covered by newly regenerated cartilage after 1 year after adequate correction of varus deformity by high tibial osteotomy without antologous chondrocyte implantation.

Background: The aims of this study were to investigate the results of opening-wedge high tibial valgus osteotomy in patients with medial compartment osteoarthritis of the knee and to examine the usefulness of hydroxyapatite wedges as the supporting material., Methods: Medial opening-wedge osteotomy was performed in twenty-one osteoarthritic knees in eighteen patients who had a mean age of 66.6 years. The mean duration of follow-up was 78.6 months. A medial transverse osteotomy was performed proximal to the tibial tuberosity, with the most lateral 10% of the tibia left intact. The medial side of the osteotomy site was opened to the desired angle of correction. Two hydroxyapatite wedges of the same size (5.0, 7.5, or 10.0 mm) were inserted into the opened osteotomy site along with bone grafts, and the fragments were fixed with two plates. The angle of correction could be adjusted by altering the direction of wedge insertion. The goal was to achieve a final standing alignment of 10 degrees of anatomical valgus angulation., Results: All patients had pain relief and improvement in walking ability after the osteotomy. The mean knee and function scores of the American Knee Society were 60.2 +/- 5.3 and 48.1 +/- 10.4 points, respectively, before the osteotomy and 94.3 +/- 7.3 and 93.1 +/- 9.8 points, respectively, at the time of the final follow-up. Limb alignment, expressed as the standing femorotibial angle, was corrected from 180 degrees +/- 2.9 degrees preoperatively to 169.7 degrees +/- 3.7 degrees (10.3 degrees of anatomical valgus angulation) at the time of the latest follow-up. There were no cases of recurrence of varus deformity or collapse of the hydroxyapatite wedges., Conclusions: After a mean duration of follow-up of 6.6 years, we found that the medial opening-wedge osteotomy of the proximal part of the tibia provided satisfactory clinical results for patients with osteoarthritis of the knee. Use of the porous hydroxyapatite wedges resulted in no collapse or subsidence at the osteotomy site., Level of Evidence: Therapeutic study, Level IV (case series [no, or historical, control group]). See p. 2 for complete description of levels of evidence.

In order to investigate the change in limb alignment in cases of knee flexion deformity, 17 male volunteers aged from 25 to 35 years with no complaints and no knee disorders were selected. The femorotibial angle (FTA), which is the lateral angle at the intersection between the femoral axis and the tibial axis in an anteroposterior radiograph, was employed as an index of limb alignment. FTA in standing on one leg with and without knee flexion was measured. The mean standing FTA was 179.4+/-19 degrees in full extension, which decreased to 176.9+/-2.5 degrees in a mean flexion position of 18+/-3.3 degrees (range 15-25 degrees ) (P<0.002), and in all cases, standing FTA in flexion was smaller (more valgus-angulated) than that in full extension. There was a significant positive relationship with a straight regression line (D=0.101KFA + 0.296, R=0.8505) between the angle of knee flexion (KFA) and the difference (D) in standing FTA between full extension and knee flexion. We conclude that limb alignment became more valgus-angulated with an increase in flexion deformity.

In order to obtain better range of motion in knees with osteoarthritis, medial and lateral parapatellar retinaculo-capsular release operations were performed at the time of high tibial osteotomy, with fixation using dual plating on medial compartmental knee osteoarthritis (29 knees) or spontaneous osteonecrosis of the medial femoral condyle (15 knees). At removal of the blade plate, 1 to 2 years after the initial osteotomy, the same release procedures were performed together with resection of adhesive soft tissue and resection of osteophytes, which were obstacles to full flexion. A grading system (Grade 0-3) was proposed to evaluate the duration (min) of formal floor sitting. After these procedures, the patients were able to sit on the floor with 155-165 degrees of flexion for more than 30 min (Grade 3) in 20 knees, for 10-29 min (Grade 2) in seven, for less than 10 min (Grade 1) in nine and were unable to sit on the floor (Grade 0) in eight knees. Maximum knee flexion and total range of motion were 142+/-8.4 degrees and 137+/-11 degrees before and 152+/-6.6 degrees and 151+/-7.4 degrees after surgery, respectively. The American Knee Society Knee Score and Function Score were 61+/-17 and 46+/-16 before, and 97+/-5 (P<0.0001) and 91+/-13 (P<0.0001) after surgery at the final follow-up, respectively. The femoro-tibial angle in standing with one leg was 183+/-6 degrees (3 degrees of anatomical varus angulation) before and 170+/-3 degrees (P<0.0001) (10 degrees of anatomical valgus angulation) after surgery., (Copyright 2002 Elsevier Science B.V.)

High tibial osteotomy was performed in 73 knees of 50 patients with medial and patellofemoral compartmental osteoarthritis of the knee, which was combined with anterior advancement of the distal fragment. At the operation, parapatellar release of the retinaculum and subperiosteal elevation of contracted medial soft tissue were also adjoined. The average age of the patients at the time of surgery was 64 years. The follow-up period was an average of 58 months. On overall clinical results assessed with the Knee Society score, the average total knee score was improved from preoperative 50 points to postoperative 94, and the preoperative average functional score of 47 points increased to 92 postoperatively. At follow-up, pain from a grinding patella was not found in 68 of 73 knees and pain from grinding and deviating of the patella was relieved in more than 96% of all cases. The mean femorotibial angle was reduced from preoperative 185 degrees to postoperative 167 degrees. On skyline view, the width of the lateral facet joint space was widely opened postoperatively, particularly on the flexion angle of 90 degrees. This operative procedure successfully relieved patellofemoral symptoms of the patients with medial and patellofemoral compartmental osteoarthritis of the knee.

A porous hydroxyapatite (highly purified synthetic Ca10(PO4)6(OH)2) wedge was inserted into the tibia in 10 knees of 7 patients with osteoarthritis of the knee who underwent high tibial osteotomy. The interface of this HA wedge with bone was histologically examined in undecalcified specimens obtained at the time of hardware removal in all 10 knees, and total incorporation of the HA into bone was observed, with no inflammatory reaction. The proportion of pores that were filled with regenerated bone within 300 microm from the interface was 71.8 +/- 10.1% (mean +/- S.D.), and it was positively correlated with the time from implantation to biopsy. Radiodensity of the HA wedge was measured during the follow-up period, and it did not change significantly within 36 months after osteotomy. Our study concluded that bone ingrowth into the HA block slowly progressed and was correlated with the passage of time.

A mixture of hydroxyapatite (HA) particles and plaster of Paris (POP) with saline solution was injected into the bone marrow of 30 unilateral tibiae of 30 rabbits. As a control, POP with saline solution was similarly injected into the bone marrow of 30 unilateral tibiae of 30 additional rabbits. Five rabbits in each group were killed 2, 4, 8, 12, 24 and 40 weeks after injection. Histological examination was performed on three tibiae of five killed animals, and X-ray diffraction analysis of the bone marrow was performed on the remaining two tibiae. In two of three tibiae, bridges of new bone were formed between the hydroxyapatite particles and the cortical bone, 4 weeks after the injection of the HA particle-POP mixture. New bone formation was seen in all three tibiae at 8 weeks and thereafter. No new bone formation was observed in the tibiae of the control group. The affinity index, a parameter of osteogenesis, was 0% at 2 weeks, 52.2+/-14.0% at 4 weeks, 74.8+/-5.3% at 8 weeks, 86.1+/-6.1% at 12 weeks, 90.1+/-8.3% at 24 weeks and 92.8+/-4.1% at 40 weeks after injection. Statistically significant increases were found between the affinity indexes of 2 weeks and 4 weeks and between those of 4 weeks and 8 weeks, p < 0.03 and p < 0.05, respectively. Between 12, 24 and 40 weeks, the indexes showed tendencies toward increases. X-ray diffraction of bone marrow of two tibiae into which HA particle-POP mixture or POP alone was injected showed that POP had disappeared 8 weeks after injection.

The synovium of the osteoarthritic knee was investigated for pathological changes after high tibial osteotomy (HTO) in a prospective two-year follow-up study. The series included 11 osteoarthritic knees in 9 patients with a mean age of 57 +/- 8 years (range: 47 to 70 years). Synovial specimens were obtained from the medial part of the knee just above the medial meniscus at the time of HTO, and taken from a different medial portion from the initial biopsy at the time of removal of the internal fixation (mean interval: 21 +/- 4 months). Lining cell hyperplasia, villous hypertrophy, cell infiltration, and vascular proliferation, observed in the first biopsy specimens, were less discernible in the samples from the second biopsy, which were obtained at the time of the removal of the fixation device. Immunohistochemical staining of the specimens revealed that cartilage fragments positive for type 2 collagen were surrounded by proliferating lining cells at the time of osteotomy. These lining cells were predominantly stained with anti-CD68 antibody for macrophage lineage cells. The mean numbers of type 2 collagen-positive fragments and CD68-positive cells in the lining layer at HTO were 9.1 +/- 6.2 (3 to 26) and 30.8 +/- 11.0 (17 to 55) per high power field (x400), respectively, while they were 1.1 +/- 1.2 (0 to 4) (p < 0.005) and 14.8 +/- 4.7 (7 to 21) (p < 0.01), respectively, at the time of removal. The number of these cartilage fragments decreased markedly after correction of the varus deformity by HTO. In conclusion, the excessive pressure on the medial compartment of the osteoarthritic knee with a varus deformity can cause wearing of the articular cartilage and fragmentation. The cartilage fragments might stimulate macrophage lineage cells in the lining layer and might cause synovitis in osteoarthritis. After correction of the varus deformity by HTO, the synovitis subsided because there were fewer cartilage fragments and less wear.

The cortical bones of swine were cut into plates measuring 40 x 10 x 2 mm and scanned by quantitative computed tomography (QCT). Compressive loading tests were performed at 100 Newtons, and the strain on the bone was measured with strain gauges. The mean Young's modulus and Poisson's ratio of one hundred specimens were 19.4 +/- 5.8 GPa and 0.34 +/- 0.09, respectively. A positive correlation (r = 0.47 +/- 0.11, p < 0.001) was observed between Young's modulus and the bone density of specimens determined by QCT, which suggests that QCT values might directly predict Young's modulus of cortical bone.

Radiographically demonstrated osteosclerosis was quantitatively evaluated in knees with medial compartmental osteoarthritis by dual xray absorptiometry. Bone density was measured in various areas of 144 knees with medial compartmental osteoarthritis, 23 knees of which were treated with high tibial osteotomy. The bone mineral density of the medial femoral and tibial condyles was greater than that of the lateral femoral and tibial condyles in all knees with medial compartmental osteoarthritis. The ratios of bone mineral density of the medial condyles to that of the lateral condyles were found to increase significantly with the progression of osteoarthritis. There was a significant positive regression line correlation between those ratios and the increase of varus deformity as expressed by the standing femorotibial angle. The former were calculated to be 1.0 when the latter was nearly 170 degrees (10 degrees anatomic valgus angulation). The ratio of bone mineral density of the medial femoral condyles to the lateral femoral condyles decreased sharply in all 23 knees within 1 year after high tibial osteotomy.

The change of patellar height after the displacement of tibial tuberosity and its effect on the improvement of clinical signs of knees was studied. The anterior displacement of tibial tuberosity was performed on fourteen knees and the anteromedial displacement on twenty knees with patellofemoral arthrosis of twenty-nine patients, four men and twenty-five women with the age at operation ranging from 47 to 79 years (average: 58.3). The anteromedial displacement of tibial tuberosity was performed on ten knees and medial displacement on fifteen knees with recurrent patellar dislocation (eleven knees) or patellar subluxation (fourteen knees) of twenty-four patients, two men and women with the an age range from 14 to 37, (average: 22.4). Patellar height was measured on lateral view by the Insall-Salvati method using Ligament/Patella ratio (Lt/Lp ratio). Ligament/Patella ratio of the older group with patellofemoral arthrosis was decreased significantly (p < 0.01) after surgery, from 1.10 to 0.94. The ratio of the younger group with patellar dislocation or subluxation showed no significant changes, but of seven knees with high riding patella, which ratio revealed more than 1.2 before operation, decreased significantly (p < 0.001) from 1.47 to 1.31. The postoperative patella baja had no poor effect on the improvement of clinical signs.

Patellofemoral compressive force was measured before and after anterior displacement of the tibial tuberosity for patellofemoral disorders on 30 knees in 28 patients. All patients selected for this experiment were those who obtained relief of pain in the activities of daily living. Twenty-five women and three men, with an average age of 54 years (range, 21-79 years), were followed an average of 38 months (range, 24-84 months). The maximum strength of knee extension was measured by a myodynamometer with the knee at 45 degrees flexion. Patellofemoral compressive force was calculated using a vector of quadriceps muscle power. At the final follow-up evaluation, the quadriceps lever arm increased in all knees with an average rate of increase of 20% +/- 2%. The maximum strength of knee extension increased in all but three knees with an average rate of increase of 147% +/- 27%. Patellofemoral compressive force increased in 22 knees, was unchanged in five, and decreased in three, with an average rate of increase of 67% +/- 15% compared with the preoperative level.

High tibial osteotomies were performed on 136 osteoarthritic knees for correction of varus deformity. Before osteotomy all patients experienced moderate or severe pain, and the knees showed lateral thrust on weight-bearing. The patients were followed up for one to five years. Marked relief of pain was obtained in 112 knees, and the patients were satisfied with the result of operation in 122. These painless knees showed no lateral thrust, and in the majority the deformity had been adequately corrected, with post-operative femoro-tibial angles (standing) ranging from 165 degrees to 174 degrees. Four of 28 knees with femoro-tibial angles of 175 degrees to 179 degrees, when measured one year after operation, showed recurrence of varus deformity three years after osteotomy. Preoperative ranges of knee motion were well maintained after osteotomy even when arthrotomy had also been undertaken. Intra-articular assessment in two patients, several years after operation, showed that the most degenerated portions of the articular surface were completely covered by a fibrocartilagenous layer, with no bare bone. High tibial osteotomy is most effective in osteoarthritic knees with varus deformity, when correction is made to a femoro-tibial angle (standing) of 170 degrees (10 degrees valgus).

In total knee arthroplasty, the top of fibular head sometimes has to be resected simultaneously during cutting tibial plateau. Therefore, tibial plateau-fibular head distance was measured in the 244 normal knees of 125 Japanese volunteers (80 men, 45 women), with average age of 27 years ranging from 21 to 40 years. Tibial plateau-fibular head distance was measured using lateral view of knee roentgenogram. The average distance was 6.1 +/- 2.5 mm in men (range, -0.5 to 12.5 mm), and 4.7 +/- 2.6 mm in women (range, -2.5 to 12.0 mm), which was thinner than that of tibial component of conventional knee prosthesis (6-8 mm or over). The relatively high level of fibular head in Japanese may disturb proper positioning of tibial component and transmit load to tibial component in weight bearing, resulting in gradual medial tilting of the tibial component. Resection of either a tip of the fibular head or a segment of the shaft may solve this problem.

Surgical techniques were described on tibial osteotomy above the tuberosity, the fragments of which were fixed with a Koshino blade plate. Postoperative clinical results on 176 knees with medial compartment osteoarthritis of 138 patients with an average age of 62.1 years were excellent in 110 and good in 55 knees with an average of 5.5 years' follow-up. The best knee score was obtained in the knee with postoperative limb alignment of 6 to 15 degree valgus angulation (standing). The results were satisfactory, especially in postoperative management, which was much easier with the Koshino blade plate fixation than with other methods. The sinking of the osteotomy site was checked through observation of screw movement in the slot of the plate during postoperative management in 53 selected knees, and the averaged distance of sinking was 3.9 +/- 2.5 mm. The time of mechanical bone union judged by cessation of sinking averaged 12.9 +/- 6.2 weeks after osteotomy.

High tibial osteotomy to correct a varus or valgus deformity was performed on thirty-seven knees (thirty-six patients) with spontaneous osteonecrosis of the femoral condyle (thirty-five medial and two lateral). Drilling or bone-grafting of the necrotic lesion was done concomitantly with the osteotomy in twenty-three knees. Follow-up periods ranged from two years to eight years and six months. Preoperative pain was relieved and walking ability was improved in thirty-five knees. The clinical results, as rated by a knee score, were better in those knees with osteonecrosis of the medial femoral condyle and a postoperative femorotibial angle (as measured on a standing roentgenogram) ranging from 164 to 173 degrees (7 to 16 degrees of valgus angulation). Postoperatively in seventeen knees. Roentgenographic improvement was greater in those knees in which tibial osteotomy was performed concomitantly with bone-grafting or drilling. Postoperative arthrotomy in eight knees showed that the necrotic lesion was covered with a white layer of fibrocartilage in three of the four knees that had had osteotomy more than one and one-half years previously.