The effect of closed wedge high tibial osteotomy on tibial slope: a radiographic study

In recent years there has been a renewed interest in high tibial osteotomies (HTOs). The development of new instruments and better fixation devices has significantly simplified the surgical procedure. This technique is frequently used to correct alignment in the frontal plane. However, changes in the sagittal plane following closed wedge HTO have not been appropriately investigated. Hence, the purpose of this study was to investigate any possible alteration of the tibial slope introduced by closed wedge HTO. In addition, we also investigated whether there is a correlation between changes of the frontal plane and alteration of the tibial slope in the sagittal plane. In a retrospective study, radiographs of 67 patients (41 males, mean age 36.6 and 26 females, mean age 39.4 years) who underwent a closed wedge HTOs or removal of hardware for a previous HTO were reviewed.The frontal plane was corrected by a mean of 7.9° (6–14°). The mean posterior tibial slope on the preoperative images averaged 6.1° (0–12°). The postoperative radiographs demonstrated a significant (P=0.0001) decrease of the posterior tibial slope to a mean of 1.2°. The magnitude of HTO in the frontal plane had no significant effect (P=0.739) on the postsurgical posterior tibial slope in the sagittal plane.     

胫骨高位截骨术:闭合与开放楔形截骨对比

目的比较胫骨高位截骨术中闭合楔形截骨法(闭合楔)与开放楔形截骨法(开放楔)的临床结果及影像学特点。方法选取2013年7月至2014年6月北京积水潭医院矫形骨科收治的因膝内翻畸形施行的29例(44膝)胫骨高位截骨术患者。其中16例(24膝)采用闭合楔形截骨术,13例(20膝)采用开放楔形截骨术,均采用Tomofix系列钢板进行固定,随访时间分别为平均18.3个月(18~24个月)和16.6个月(18~25个月)。于末次评价两组患者Lysholm评分的变化、关节活动度变化及并发症发生情况。影像学方面,对比两组患者力线矫正的准确性、矫正角度及,术前、术后髌骨高度的变化及胫骨平台后倾角的变化。结果闭合楔组患者Lysholm评分从术前的(96.8±6.3)分增加至术后的(98.2±3.3)分(P=0.828);开放楔组患者从术前的(95.4±8.3)分增加至术后的(98.1±3.4)分(P=0.656)。闭合楔组关节活动度术前为(137.7°±14.2°),术后为(133.5°±15.0°)(P=0.146);开放楔组术前为(138.5°±15.6°),术后为(134.3°±17.3°)(P=0.207)。闭合楔组有1例(1膝,4.2%)出现腓神经损伤症状,半年后恢复;另有1例(1膝,4.2%)出现截骨延迟愈合,术后6个月复查时截骨愈合。闭合楔组与开放楔组畸形矫正满意率分别为87.5%和90%(P=1.000)。闭合楔组矫正胫骨内翻的角度为(10.3°±4.3°);开放楔组为(9.4°±5.3°)(P=0.289)。在髌骨高度方面,术后闭合楔组Caton Deschamps指数(CDI)从(1.09±0.17)增大至(1.11±0.18)(P=0.761);开放楔组从(1.16±0.25)减小至(0.99±0.23)(P=0.034)。闭合楔组胫骨后倾角从(13.4°±5.1°)减小至(9.4°±5.3°)(P=0.010);开放楔组从(12.0°±4.1°)增大至14.9°±5.1°(P=0.050)。结论闭合楔与开放楔两种截骨技术都能获得满意的临床结果。开放楔可能减小髌骨高度,故对于术前即存在髌骨低位的患者,应避免采用开放楔,或者采用开放楔时冠状面截骨斜向前下方,将胫骨结节保留在近端截骨块,以避免进一步加重髌骨低位,影响关节活动。由于闭合楔可能减小胫骨平台后倾而开放楔可能增加后倾,故应按照实际需要个体化地选择截骨方式。     

Medial opening wedge high tibial osteotomy: how i do it

Opening wedge high tibial osteotomy allows correction of alignment deformities in all planes, particularly in planned alterations to the tibial slope in the sagittal direction. In addition, corrections of 5° or less are easier to achieve than with closing wedge osteotomy. This technique has been previously described with favorable results. Throughout the procedure, attention to detail is essential for minimizing the potential for complications.     

Primary stability of four different implants for opening wedge high tibial osteotomy

Since a significant number of implant failures have been reported in association with the procedure of open wedge valgus high tibial osteotomy, the initial biomechanical stability of different fixation devices was investigated in this study. Fifteen third generation Sawbones composite tibiae were used as a model. Four different plates were tested: a short spacer plate (OWO) (n=4), a short spacer plate with multi-directional locking bolts (MSO) (n=5), a prototype version of a long spacer plate with multi-directional locking bolts (MSOnew) (n=2), and a long medial tibia plate fixator with locking bolts (MPF) (n=4). All opening wedge osteotomies were performed by the same surgeon (PL) in a standardized fashion. Axial compression of the tibiae was performed using a materials testing machine under standardized alignment of the loading axis. Single load to failure tests as well as load-controlled cyclical failure tests were performed. The required force and cycles to failure were recorded. Osteotomy gap motion was measured using linear displacement transducers. Residual stability after failure of the opposite lateral cortex was analysed. Failure occurred at the lateral cortex bone-bride in all tested implants. The rigid long plate fixator (MPF) resisted the greatest amount of force (2,881 N) in the single load to failure tests. In the cyclical load-to-failure tests, the constructs with MPF resisted more than twice the amount of loading cycles when compared to the short spacer plates. The osteotomy gap motion was smallest in the MPF, with a reduction of the displacements of up to 65, 66 and 88%, when compared to OWO, MSO and MSOnew, respectively. The highest residual stability after failure of the lateral cortex was observed in MPF as well. The results suggest that the implant design strongly influences the primary stability of medial opening wedge tibial osteotomy. A rigid long plate fixator with angle-stable locking bolts yields the best results.     

Open wedge high tibial osteotomy using fractioned drill osteotomy: a surgical modification that lowers the complication rate

We investigated retrospectively 132 cases of open wedge high tibial osteotomy using an external fixation device, concentrating on the rate of neurological complications. One group of patients underwent surgery according to the conventional technique (n=89). The rate of transient neurological complications was 15.7%; 7 months after surgery the rate of persistent deficits was 12.4%. For the second group (n=43) a modified surgical technique was used that lowered the complication rate significantly (transient deficits 14%, persistent deficits 4.7%). In the modified technique the osteotomy is not performed in the conventional way using an oscillating saw but through consecutive drill holes of increasing diameter followed by osteoclasis. The lower complication rate in the second group is mainly due to the less extensive approach that leads to a smaller number of postoperative tibialis anterior syndromes (type B lesion). No differences were found with type C lesions (extension deficit of D1). No complete peroneal nerve palsy (type A) occurred in either group. We conclude that the reduction of neurological complications in group 2 is related to the less extensive approach of the proposed technique.     

Change in gait after high tibial osteotomy: A systematic review and meta-analysis

We conducted a meta-analysis to analyze how high tibial osteotomy (HTO) changes gait and focused on the following questions: (1) How does HTO change basic gait variables? (2) How does HTO change the gait variables in the knee joint? Twelve articles were included in the final analysis. A total of 383 knees was evaluated. There were 237 open wedge (OW) and 143 closed wedge (CW) HTOs. There were 4 level II studies and 8 level III studies. All studies included gait analysis and compared pre- and postoperative values. One study compared CWHTO and unicompartmental knee arthroplasty (UKA), and another study compared CWHTO and OWHTO. Five studies compared gait variables with those of healthy controls. One study compared operated limb gait variables with those in the non-operated limb. Gait speed, stride length, knee adduction moment, and lateral thrust were major variables assessed in 2 or more studies. Walking speed increased and stride length was increased or similar after HTO compared to the preoperative value in basic gait variables. Knee adduction moment and lateral thrust were decreased after HTO compared to the preoperative knee joint gait variables. Change in co-contraction of the medial side muscle after surgery differed depending on the degree of frontal plane alignment. The relationship between change in knee adduction moment and change in mechanical axis angle was controversial. Based on our systematic review and meta-analysis, walking speed and stride length increased after HTO. Knee adduction moment and lateral thrust decreased after HTO compared to the preoperative values of gait variables in the knee joint.     

胫骨高位截骨术失败后行全膝关节假体置换术的长期疗效观察

目的 针对胫骨高位截骨术(high tibial osteotomy,HTO)失败后行全膝人工关节置换术(total knee arthmplasty,TKA)进行长期疗效观察,分析其远期临床疗效及术中注意事项.方法 选择法国Medico-Chirurgical du Cedre中心1990年3月-1992年6月18例(19膝)HTO术后失败的患者并行TKA治疗.所有关节均有内外侧间室退变,4例伴有外侧胫骨平台中度骨缺损.采用X线测量和膝关节协会评分系统(Knee Society Scoring System,KSS)评估手术疗效,X线测量包括髋膝踝角(hip knee ankle,HKA)、α角、β角、髌骨指数、胫骨平台后倾角等.结果 TKA中11膝因HTO术后严重外翻和髌骨外侧半脱位而在TKA中行胫骨结节截骨及内移术;5膝因侧方软组织条件差或平衡不良而置入半限制型假体.随访时18例患者中2例死亡,获访16例(17膝).无失访和翻修病例.7膝在随访时出现严重聚乙烯衬垫磨损,但临床症状较轻.随访时KSS平均147.2分,优良率82%. 结论 HTO术后行TKA临床疗效优良.但由于外翻畸形和髌股关节并发症多见,可能需采用胫骨结节截骨术并内移术;HTO术后外翻畸形为TKA软组织平衡和胫骨截骨造成一定困难,术前应准备置入限制性更高的假体.     

Improvements in spinal alignment after high tibial osteotomy in patients with medial compartment knee osteoarthritis

Since the correlation between spinal and lower extremity alignments is high, high tibial osteotomy (HTO) surgery may also affect spinal alignment, where the spinal alignment parameters are the most important parameters for the evaluation of spinal disorders. In this study, the effect of HTO surgery on spinal alignment during gait was investigated by comparing spinal alignment parameters between patients with knee osteoarthritis (OA) and healthy young controls. Eight patients (age, 55.0 ± 5.1 years; height, 160.3 ± 7.0 cm; weight, 71.3 ± 14.1 kg) with a medial compartment knee OA participated in the gait experiment two times approximately one week before and one year after HTO surgery and eight healthy young controls (age, 26.7 ± 1.7 years; height, 163.4 ± 6.5 cm; weight, 58.4 ± 11.3 kg) participated only once. Cervical curvature angle, thoracic curvature angle, lumbar curvature angle, coronal vertical axis, and coronal pelvic tilt in the coronal plane and cervical lordosis, thoracic kyphosis, lumbar lordosis, sagittal vertical axis, and sagittal pelvic tilt in the sagittal plane were estimated using motion analysis system with skin markers. All spinal alignment parameters after HTO surgery were significantly closer to those of healthy young subjects than those before HTO, especially in the coronal plane. These findings suggest that the HTO had a positive effect on spinal alignment, as well as lower extremity alignment, and moreover, reduced the abnormality that may result in spinal problems such as degeneration or pain.     

Tibial slope and high tibial osteotomy using the circular external fixator

Alteration of tibial slope is one of the important anatomical changes of the proximal tibia after high tibial osteotomy. Increased or decreased tibial slope can effect further total knee prosthesis procedure. In this retrospective study, 18 knees of 17 patients (17 female, mean age 51 range 43–61, mean BMI is 33.6 ± 4.6 kg/m²) who were applied high tibial osteotomy using circular external fixator due to medial compartment arthrosis of the knee were evaluated in terms of tibial slope changes. While mean correction about 12.3° in mechanical femoro-tibial angle was obtained in frontal plan (P = 0.0001), significant change in tibial slope was not determined in sagittal plan (P = 0.127). The mean posterior proximal femoral angle values were measured as 79.5 ± 2.1° preoperatively and as 80.3 ± 2.7° postoperatively and found to fall into the normal range (80.4 ± 1.6°). As there is no significant alteration in tibial slope after high tibial osteotomy performed with the Ilizarov system, complications due to alteration in tibial slope will not be experienced in follow-up or in further total knee prosthesis procedure.     

Clinical results and radiographical evaluation of opening wedge high tibial osteotomy for spontaneous osteonecrosis of the knee

We evaluated the clinical outcomes, in terms of early weight bearing, of using opening wedge high tibial osteotomy (OWHTO) to treat spontaneous osteonecrosis of the medial femoral condyle of the knee (SONK) using TomoFix™ and artificial bone substitute. Damaged cartilage tissue was removed and drilling of the necrotic area followed by OWHTO was performed in 30 knees from 30 patients with an average age of 71 years (range 58–82) at the time of operation. Patients were allowed to undertake partial weight-bearing exercises 1 week after the osteotomy procedure, with all patients performing full weight-bearing exercise at 2 weeks post-surgery. The mean follow-up period was 40 months (range 24–62). All of the SONK patients could walk with a full weight-bearing load, using only a T-cane, at 2 weeks after undergoing OWHTO. Clinical assays, including the mean American Knee Society Score and Function Score, showed significant improvements from 51 to 93 points, and 58 to 93 points, respectively. Prior to surgery, the average femoro-tibial angle (FTA) during standing was 181 (1° anatomical varus) and had significantly changed to 170 (10° valgus) at the time of follow-up. There were no cases of non-union, or implant failure in any of our patients. In addition, none of the patients could sit in the Japanese style prior to surgery, but 21 of 30 patients (70%) could do so after treatment. Arthroscopic findings could be observed in 24 out of 30 cases at implant removal. Necrotic area in each case was covered with fibrous cartilage-like tissue completely. Drilling of the necrotic area followed by OWHTO with TomoFix and artificial bone substitute is an effective treatment for SONK as it results in pain alleviation and regeneration of the fibrous cartilage tissue over the necrotic legion. In addition, an early weight-bearing exercise program is possible after this procedure and full weight-bearing can be achieved at two weeks after surgery.     

Simultaneous bilateral opening-wedge high tibial osteotomy with early full weight-bearing exercise

Simultaneous bilateral opening-wedge high tibial osteotomies (OWHTOs), using the TomoFix fixation device and artificial bone wedges (β-TCP) were performed on 20 knees of 10 patients with an average age of 67 years (range 53–75) at the time of the operation. We established an early weight-bearing exercise program during which patients were permitted partial weight-bearing exercise 1 week after osteotomy, with all patients performing full weight-bearing exercise at 3 weeks. The follow-up period was an average of 15 months (range 6–39). The American Knee Society Score and the Function Score were improved significantly from 46 ± 8.1 to 92 ± 6.8 points and 67 ± 7.9 to 95 ± 7.9 points, respectively. Prior to surgery, the average lateral femoro-tibial angle (FTA) during standing was 182 ± 2.3° (2° anatomical varus) and significantly changed to 170 ± 2.5° (10° valgus) at the time of follow-up. There were no cases of infection, non-union, or implant failure. Overall, this procedure was highly successfully in correcting knee malalignment in patients with medial compartmental osteoarthritis. In our study also, there was no evidence of correction loss, implant failure, collapse of the artificial bone wedges, or screw loosening. Simultaneous treatment of bilateral OWHTOs under a single administration of anesthesia appears to be superior to separate procedures of unilateral surgical procedures in providing the potential benefits of minimizing hospitalization, reducing costs and maximizing clinical outcomes for patients and institutions.     

Heterotopic ossification post navigated high tibial osteotomy

The authors present a case of heterotopic ossification (HO) following a navigated high tibial osteotomy which necessitated a second surgical procedure. There is no evidence in the literature of HO following the use of invasive navigation reference markers. Although osseous reference marker fixation is the current standard technique, this case underscores the need for non-invasive reference markers.     

Nerve and vessel injuries during high tibial osteotomy combined with distal fibular osteotomy: a clinically relevant anatomic study

Based on our clinical experience and an anatomical study, we examined the conditions under which injury to the popliteal artery, tibial nerve or peroneal nerve and its branches may occur during high tibial osteotomy. In 250 high tibial osteotomies performed in our department, we observed the following intraoperative complications. (1) The popliteal artery was severed in 1 patient and repaired by the same surgical team using a microsurgical technique. (2) A tibial nerve paresis also occurred in 1 patient. (3) In 3 patients, temporary palsy of the anterior tibialis muscle was documented. (4) In 4 other patients, palsy of the extensor hallucis longus occurred. To investigate the causes of these complications in the popliteal artery, tibial nerve and branches of the peroneal nerve, we dissected the neurovascular structures surrounding the area of the osteotomy in 10 cadaveric knees and performed a high tibial osteotomy in another 13 cadaveric knees. We concluded the following. (1) The popliteal artery and tibial nerve are protected, at the level of the osteotomy, behind the popliteus and tibialis posterior muscles. Damage can occur only by placing the Hohman retractor behind the muscles. The insertion of the muscles is very close to the periosteum and can be separated only with a scalpel. (2) The tibialis anterior muscle is innervated by a group of branches arising from the deep branch of the peroneal nerve. In two-thirds of the dissected knees, we found a main branch close to the periosteum, which can be damaged by dividing the muscle improperly or due to improper placement and pressure of the Hohman retractor. This may explain the partially reversible muscle palsy. (3) The extensor hallucis longus is also innervated by 2–3 thin branches, arising from the deep branch of the peroneal nerve, but in 25% of the specimens, only one large branch was found. This branch is placed under tension by manipulating the distal tibia forward. Thus, it may be damaged by the Hohman retractor during distal screw fixation, tensioned by hyperextension or directly injured during midshaft fibular osteotomy. Received: 12 May 1997 Accepted: 12 November 1997     

Comparison of augmented and non-augmented anterior cruciate ligament reconstruction combined with high tibial osteotomy

In a follow-up study 27 patients were evaluated after anterior cruciate ligament (ACL-)reconstruction combined with high tibial osteotomy because of chronic rupture of the ACL, cartilaginous lesions of the medial compartment and varus malalignment. They were divided into two groups. In 14 patients (non-LAD group) ACL reconstruction was performed using the central third of the autologous patellar tendon modified according to Eriksson-Trillat. Thirteen patients (LAD group) underwent repair with the same technique, but a Kennedy ligament augmentation device (LAD) in hot dog technique and fixed over the top was added. The postoperative treatment was the same in both groups. All patients were examined according to IKDC criteria. KT-1000 arthrometer testing at maximum manual traction was performed. Although the mean follow-up interval was more than double in the non-LAD group (non-LAD: 127 months vs LAD: 58 months), the subjective and clinical results, IKDC evaluation and KT-1000 arthrometer testing results were similar, showing no statistically significant difference. Further, no complications due to the use of LAD occurred. In this study no evident functional or clinical advantage from the augmentation performed could be shown.Investigation performed at the Department of Orthopaedic and Trauma Surgery, University Hospital Basle, Switzerland. No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Funds were received in total or partial support of the research or clinical study presented in this article. The funding sources were SUVA Assurance, Lucerne, and the science fund of the University Hospital Basle     

Tibial slope changes following dome-type high tibial osteotomy

The tibial slope is essential in knee biomechanics, both for ligament function and knee kinematics. High tibial osteotomy (HTO) designed primarily to correct frontal plane malalignment in osteoarthritis of the knee joint can cause unintentional tibial slope changes. We evaluated tibial slope changes in 40 knees in patients with medial compartment osteoarthritis treated by dome-type HTO and external fixation on one side, and followed up for 55 months on average. Four different tibial slope measurement methods (anterior tibial cortex, proximal tibial anatomic axis, posterior tibial cortex, and proximal fibular anatomic axis) were used preoperatively and postoperatively on both sides. Patients were allocated into three groups according to their final frontal plane alignment of the knee joint (hypercorrection, normocorrection, and undercorrection groups) based on tibiofemoral anatomic axis angle. As a whole, preoperative slope values (11.2°, 7.5°, 5.6°, and 8.2° for the four methods, respectively) displayed a significant decrease postoperatively (on average 7.9°, 4.8°, 2.2°, and 3.7°, respectively). Patients with undercorrection (or recurrence of deformity) had a more remarkable decrease in slope than those with normocorrection or hypercorrection. The higher the degree of postoperative mechanical axis valgus, the higher the degree of posterior tibial slope that resulted. Sagittal plane changes after dome-type HTO basically decreasing the tibial slope should be taken into account for subsequent reconstructive procedures such as total knee arthroplasty.     

Drop foot after high tibial osteotomy: a prospective study of aetiological factors

Drop foot is not uncommon after high tibial osteotomy for genu varum. The authors report their results of a prospective study of 16 patients operated on between May 1990 and May 1991. All patients had medial femoro-tibial osteoarthritis with a constitutional genu varum. They all had a subtraction valgus high tibial osteotomy fixed by a blade plate. The experimental protocol included clinical review, antero-lateral compartment pressure measurements, intra- and post-operative electromyography, assessment of the post-operative drainage, serum estimation of muscle ensymes and post-operative arteriography. From their own results and a literature review, the authors consider successively the different aetiological factors for post-operative drop foot. Certain deficits occur due to direct trauma on the nerve during high osteotomy of the fibula, by local high pressure due to poor haemostasis or ineffective drainage. In addition, there are several related phenomena. The pneumatic tourniquet ssensitises the nerve to trauma, and stretching of the nerve during correction of the deformation depends on the local anatomical factors and their marked variation. In order to diminish the frequency of these post-operative complications, the authors suggest limiting the surgical approach, and limiting as far as possible the traumatic manoeuvres on the nerve by using a tibial resection jig, which allows correction without forced manoeuvres. Finally, the authors discuss the benefits of using a pneumatic tourniquet.     

High tibial osteotomy alone or combined with ligament reconstruction in anterior cruciate ligament-deficient knees

High tibial osteotomy (HTO) is widely accepted as a treatment option in patients with medial unicompartimental osteoarthritis (OA) and varus morphotype of the knee. We increasingly see younger patients with a chronic anterior instability, an additional varus morphotype and beginning medial OA. Treatment options for these patients are not clear up to now. In this clinical study we compare for the first time three different treatment rationales and introduce a concept of symptom-oriented surgery in young patients with medial OA and chronic anterior instability.Materials/methods: Between 1984 and 1994 30 patients were treated with a medial unicompartimental OA and chronic anterior instability of the knee. Patients were grouped into three different groups according to treatment. 1) only HTO was performed. 2) HTO and simultaneously an ACL-reconstruction and 3) HTO and 6–12 months later an ACL-reconstruction was performed. 27/30 patients were available for follow-up. All patients had an arthroscopy before surgery. Evaluation was done according to the IKDC-protocol and X-ray documentation.Results: Pain was a major problem in all patients. None of them was completely pain-free. 8/27 patients had pain even with light activities. This included 1/11 patients of group 1, 3/8 of group 2 and 4/8 of group 3. 9/27 patients had stable knee joints with a Lachman-test of 3–5 mm. No patient had a Lachman test<3 mm. 3/11 patients of group 1, 3/8 of group 2 and 2/8 of group 3 had a Lachman test of 5–10 mm. A positive pivot-shift could be found in 9/27 patients. 2/11 of group 1, 4/8 in group 2 and 3/8 in group 3. The overall IKDC-score improved in 23/27 patients, one patient remained unchanged, two deteriorated. Radiologically a slight progression of OA could be seen in all patients. Radiological signs of OA and pain did not show any correlation. There was, however, a significant rate of postoperative complications involving 4/11 patients of group 1 and 3/8 of group 3. There were 6 major complications in 5/8 patients in group 2. Nevertheless overall patient satisfaction was high. 25/27 patients would undergo the procedure again.Conclusion: HTO is a good treatment option for younger patients with medial OA and chronic anterior instability of the knee. These patients pose a high challenge to diagnostic and operative skills of the surgeon. Main symptoms of these patients have to be analysed clearly in terms of instability and pain. In patients aged 40 and older an HTO alone is an excellent treatment option with reproducably good results. In younger patients we advise an HTO first. If instability persists, an ACL-reconstruction can be done 6–12 months later. One has to be aware that a simultaneous combined procedure has a significant complication rate. Hence if a simultaneous combined treatment is planned the surroundings including surgical technique, rehabilitation and patient compliance have to be ideal. These young patients need an activity counselling in order to realise that their knee joint has suffered significantly from the injury and ongoing high physical demands on their knee joint.     

Total knee arthroplasty following failed high tibial osteotomy: mid-term comparison of posterior cruciate-retaining versus posterior stabilized prosthesis

This study evaluated the mid-term results of total knee arthroplasty (TKA) following high tibial osteotomy (HTO), comparing posterior cruciate-retaining prostheses to posterior stabilized prostheses. The Knee Society score for the entire group (20 knees) improved significantly from 62 (median) preoperatively to 87 at the latest follow-up. The postoperative Knee Society score of 85 in posterior cruciate-retaining prostheses (8 knees) was significantly inferior to the 94 score in posterior stabilized prostheses (12 knees). Of Knee Society score, Stability and ROM scores (17 and 21, respectively) in posterior cruciate-retaining TKA were inferior to those in posterior stabilized TKA (25 and 24, respectively). Since postoperative knee instability due to posterior cruciate ligament (PCL) insufficiency is thought to contribute to the inferior results of posterior cruciate-retaining prostheses after HTO, PCL-substituting TKA would be suitable for use after HTO.     

The influence of open and closed high tibial osteotomy on dynamic patellar tracking: a biomechanical study

High tibial osteotomy (HTO) can cause alterations in patellar height, depending on the surgical technique, the amount of correction and the postoperative management. Alterations in patella location after HTO may lead to postoperative complications. However, information on changes in dynamic patellar kinematics following HTO is very limited. We conducted a biomechanical study, to analyze the effect of open (OWO) and closed wedge osteotomy (CWO) on patellar tracking. Using an inventive experimental set-up, we studied the 3D dynamic patellar tracking in ten cadaver knees before and after valgus HTO. In each specimen, corrections of 7° and 15° of valgus according to, both, the OWO and CWO technique, were performed. Patellar height significantly increased with CWO and decreased with OWO. Both, OWO and CWO led to significant changes in the patellar tracking parameters tilt and rotation. We also found significant differences between OWO and CWO. Valgus high tibial osteotomy increased the medial patellar tilt and reduced the medial patellar rotation. These effects were more profound after OWO. No significant differences were found for the effect on medial–lateral patellar translation. These observations can be taken into consideration in the decision whether to perform an OWO or a CWO in a patient with medial compartment osteoarthritis of the knee.     

Medial opening wedge high-tibial osteotomy using a kinematic navigation system versus a conventional method: a 1-year retrospective, comparative study

High tibial osteotomy is a realignment procedure to transfer weight-bearing load to the intact compartment of the knee to alleviate symptoms, slow disease progression, and defer subsequent total knee arthroplasty. To prevent overcorrection or undercorrection, it is not only important to have an exact preoperative calculation of the desired correction angle, but it is also critical to have an accurate intraoperative technique. 85 consecutive patients (90 knees) were enrolled, who were available at 1-year follow-up after a medial opening wedge high tibial osteotomy using a kinematic navigation system or a conventional method, for medial unicompartmental osteoarthritis. On radiographic assessment, the navigation group showed better results than the conventional group in both the mechanical axis and the coordinate of the weight-bearing line on a full-length standing anteroposterior radiograph (3.9° ± 1.0° vs. 2.7° ± 2.2° of valgus, P < 0.01), (62.3 ± 2.9% vs. 58.7 ± 6.6% coordinate at the tibial plateau, P < 0.01). There was no significant difference in the alteration of tibial slope between the two groups. On clinical assessment, the navigation group showed better results in both the mean Hospital for Special Surgery knee score (84 ± 8 vs. 79 ± 7, P < 0.01) and the mean Lysholm knee score (85 ± 6 vs. 83 ± 5, P < 0.05). There was no significant difference in operation times between the two groups. Kinematic navigation-guided high tibial osteotomy is a reproducible and reliable procedure compared to conventional high tibial osteotomy.