Radiographic discrepancy of lower limb alignment between preoperative planning and postoperative opening wedge high tibial osteotomy

Abstracts / Asia-Pacific Journal of Sports Medicine, Arthroscopy, Rehabilitation and Technology 9 (2017) 12e58

Conclusion: HTO techniques can realignment, improve the relationship of knee, and make the repaired/reconstructed ligament healing in normal position and loading normal strain. Keywords: Old knee dislocation, HTO, osteotomy, malalignment

Knee - Osteotomy > High tibial osteotomy OP-003 MID-TERM SURVIVAL ANALYSIS OF HIGH TIBIAL OSTEOTOMY d A COMPARATIVE STUDY OF COMPUTER ASSISTED AND CONVENTIONAL TECHNIQUE Sang Jun Song, Dae Kyung Bae, Kang Il Kim, Cheol Hee Park. Department of Orthopaedic Surgery, College of Medicine, Kyung Hee University, South Korea Background: Various factors have been reported to be associated with the survival of an HTO, including age, gender, BMI, preoperative ROM, OA grade, and postoperative correction angle. To the best of our knowledge, no study has compared survival rates between computer-assisted and conventional HTO. The purpose of the present study was to compare the clinical and radiographic results and survival rates between computerassisted and conventional closing wedge high tibial osteotomy (HTO). Material: Data from a consecutive cohort comprising 132 computerassisted HTOs and 75 conventional HTOs using miniplate staples were retrospectively reviewed. Method: The hospital for special surgery (HSS) score and femorotibial angle (FTA) were compared between the two groups. The survival rates were also compared to procedure failure. Several variables were analyzed to determine the risk factors affecting the survival rate of the HTO. Results: The HSS scores at the postoperative one year were slightly better for the computer-assisted HTOs (87.9 vs.81.8). The average postoperative FTA was greater in the computer-assisted group (valgus 9.0
vs. valgus 7.6
, P < 0.001). The inlier of postoperative FTAs was wider in the computerassisted group (81.1% vs. 58.7%). The overall 5- and 10-year survival rates were 95.4% and 86.3%, respectively. The survival rates did not differ between the groups until 9 years (P ¼ 0.369). The postoperative FTA was the only independent factor that affected the survival rate (P ¼ 0.003). Discussion: The most important finding of the present study was that there were no significant differences in the 9-year survival rate between the computer-assisted and conventional HTO groups although the clinical and radiographic results were better for the computer-assisted group. The difference in the clinical and radiographic results could be caused by the different lengths of follow-up. Therefore, we compared not only the last follow-up results, but also the postoperative 1 year clinical results and the FTA 2 weeks postoperatively between the two groups. Although the shortterm clinical and radiographic results seemed to be better in the computerassisted group, a more sophisticated longer-term survivorship analysis will be required to prove the long-term benefits of computer-assisted HTO. Conclusion: The mid-term clinical and radiographic results of HTO were satisfactory for both computer assisted and conventional HTOs, but the survival rates deteriorated over time. The 9-year survival rate of HTO was not different between the computer-assisted and conventional HTOs. A comparative analysis of a longer-term survival rate is required. It is advisable to correct the FTA to more than 7
valgus, considering the long-term survival rate. Keywords: knee, osteoarthritis, high tibial osteotomy, closing wedge, navigation, survival

Knee - Osteotomy > High tibial osteotomy OP-005 RADIOGRAPHIC DISCREPANCY OF LOWER LIMB ALIGNMENT BETWEEN PREOPERATIVE PLANNING AND POSTOPERATIVE OPENING WEDGE HIGH TIBIAL OSTEOTOMY Kosuke Nakagawa, Shuhei Otsuki, Yoshinori Okamaoto, Tomohiko Murakami, Masashi Neo. Department of orthopedic surgery, Osaka Medical College, Japan Opening wedge high tibial osteotomy (OWHTO) is widely performed for medial osteoarthritis (OA) and osteonecrosis (ON). Concept of HTO for

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medial OA is to transfer mechanical axis to the lateral compartment of the knee, thereby reduces knee pain, and prevent OA change in medial compartment, suggesting that accurate correction of lower limb alignment is critical for getting the successful outcome after OWHTO. However, postoperative lower limb alignment is sometimes different from preoperative planning. Although several factors might be affected this discrepancy, we focused on soft tissue knee laxity. The current study evaluated the effect of soft tissue around the knee using varus / valgus stress radiography. Materials & Methods: This study involved 26 knees from 23 patients undergoing OWHTO for primary medial OA and ON from March 2014 to November 2016. 10 knees were from 8 males and 16 knees were from 15 females with the average of 65 ± 11 years old (range 35-81 years old) at the time of surgery. Preoperative planning for the degree of correction was assessed on full-length anteroposterior radiograph with the standing position as the mechanical axis passed through the lateral intercondylar eminence of proximal tibia by using softwere (Advanced Caseplan, Trauma CAD, Germany). After medial opening high tibial osteotomy site was performed with two b eTricalciumPhosphate wedges (Osferion60, Olympus Terumo Biomaterials, Tokyo, Japan) and locking plate (TomoFixTM, Synthes, Bettlach, Switzerland, FlexitSystem®, neosteo, France and Tris Medial HTO Plate System, Olympus Terumo Biomaterials, Tokyo, Japan). Radiographs were obtained both pre- and post-operatively (1 month after surgery) and hip knee ankle angle (HKA), medial proximal tibial angle (MPTA), mechanical axis (%MA), and joint line convergence angle (JLCA) were measured. Varus JLCA was defined as JLCA during manual varus stress under fluoroscopy. Valgus JLCA was defined as JLCA during manual valgus stress too. Results: The average HKA angle significantly changed from varus 5.9 ± 2.7
(varus 1
to 12
) to valgus 3.4
± 1.6
(valgus 0
to 7
,p ˂ 0.001). The average MPTA significantly changed from 84.2
± 2.7
(79
to 89
) to valgus 92.6
± 2.4
(87
to 96
,p ˂ 0.001). The average JLCA significantly changed from 3.7
± 1.9
(1
to 8
) to valgus 2.2
± 1.4
(-1
to 4
, p ˂ 0.001). The average %MA significantly changed from 22.6% ± 15.3% (-6.8% to 47.5%) to 59.7% ± 10.4% (37% to 79%, p ˂ 0.001). The average planning HKA was valgus 2.5
± 1.1
(valgus 1
to 5
) and was significantly different from postoperative HKA (p ¼ 0.038). The average planning MPTA was 92.7
± 2.6
(87
to 96
) and was not significantly different from postoperative HKA (p ¼ 0.92). Preoperatively stress tests showed that varus JLCA was 4.1
± 1.7
(1
to 7
), valgus JLCA was -0.2
± 1.5
(-2
to 3
). DHKA angle showed a moderate correlation with varus HKA angle (r, 0.46) and pre- to post differences in JLCA (r, 0.56). But, DHKA angle showed a poor correlation with valgus JLCA (r, 0.25). Discussion: The most important findings of the present study was that knee laxity which was evaluated with varus JLCA showed a correlation withDHKA angle (over correction) between preoperative planning and postoperative OWHTO. In conclusion, as knee varus laxity was getting increased, the discrepancy between preoperative planning and postoperative alignment was detected, especially with over correction. Keywords: high tibial osteotomy, hip knee ankle angle, preoperative planning, over correction

Knee - Osteotomy > High tibial osteotomy OP-006 COMPARISON OF THE METHOD USING 3D PRINTING MODEL AND PACS IN PREOPERATIVE PLANNING FOR OPEN WEDGE HIGH TIBIAL OSTEOTOMY Hee-June Kim, Hee-Soo Kyung. Department of Orthopaedic Surgery, Kyungpook National University Hospital, Daegu, Republic of Korea Purpose: The purpose was to compare the accuracy of the method using 3D printing model with the method using picture archiving and communication system (PACS) images in high tibial osteotomy (HTO). Materials and Methods: This study analyzed 40 patients with varus deformity and medial osteoarthritis. From 2012 to 2016, patients underwent HTO using either 3D printing model (20 knees) or method based on a PACS image (20 knees). After obtaining the correction angle for the target point (62.5% point of the mediolateral tibial plateau width), in the 3D printing method, the wedge-shaped 3D-printed model was designed with the measured angle and osteotomy section and was produced by the 3D