Techniques of High Tibial Osteotomy: A Review

Main intention of the research is to understand about significance of techniques associated with HTO. This research reviewed the techniques of high tibial osteotomy namely high tibial osteotomy, open wedge high tibial osteotomy, closedhigh tibial osteotomy. Patients who are suffering from knee arthritis, high tibial osteotomy assists to prevent or delay the requirement for total or partial replacement of knee to preserve damaged tissue of joint. High tibial osteotomy technique is mainly suitable for active and young patients with knee osteoarthritis. Age plays a main factor in success rate of high tibial osteotomy technique. It could be done in open wedge or closed wedge high tibial osteotomy. For some cases, surgery could be done in combined method (open wedge and closed wedge high tibial osteotomy). When compared with clinical outcomes of closed wedge high tibial osteotomy and open wedge high tibial osteotomy, open wedge high tibial osteotomy performs well in reducing the pain, duration of weight-bearing and return to normal life as soon as possible.


Introduction
Joint in knee is main and complicated joint for motion and load, entailing the PF (patellofemoral) joint and TF (tibiofemoral) joint. Joint in knee stability is mostly dependent on interacting cartilaginous and ligamentous meniscus, structures and some tendons and muscles. Loads given on tibiofemoral joint are sometimes over BW (body weight) during every day activities and average high forces for resultant were peak when climbing down the stair (346 percent BW), climbing up the stairs (316 percent BW) and walking level (261 percent BW). Force distribution between medial and lateral is relied on TF alignment and differs within various tasks like weight-bearing [1]. At the time of walking gait, distribution of load between medial and lateral differs based on tibia [2] [3]. Nearly 75 percent of load in joint passes through plateau of medial tibial at the time of single-leg stance [4].
Nowadays, OA (Osteoarthritis) is commonly seen among adults like joints disease all over the globe. It is functioned by progressive articular cartilage loss come with novel formation of bone and mostly synovial proliferation would culminate in joint function loss, pain and disability [5]. A report given by world health organization about global load of disease reveals that knee osteoarthritis (KO) mostly to become fourth main major reason of disability among females and eighth most reason among males [6].
KO is most commonly seen in India when compared with western countries and also found one of major disability like any other chronic ones. KO is seen commonly seen in elderly person but nowadays even it is affecting person age less than fifty years [7]. Both local factors such as deformity in the joint and weakness in the muscle and systemic factors like genes, sex and age seem to major factor among individual joints which develop the disease. Particular aetiological factors are not known; at the same time also encompass failure of internal remodelling system controlled by chrondrocyte, mechanical overloading and additional cartilaginous factors like vascular changes or synovial changes [8]. High tibial osteotomy (HTO) is surgical technique accepted for medial knee arthrosis compartment in young patients. HTO's biomechanical principle which redistributes the forces of weight bearing from compartment of worn towards lateral compartment thus relieves pain and lowers the progression of disease. Choosing suitable patients, accurate surgical technique and extensive planning for pre-operation are needed for successful result [9].
KO is general clinical disease which affects person above 65. Major reasons of KO are overwork, knee degenerative diseases, postural errors and more. Deformities of knee, which represent one of main reason of KO, were not taken seriously.
It could cause damage in force line at lower limb, surface wear of knee cartilage and collapse of tibial plateau which lead to KO. Most significant method of treatment in clinic is arthroplasty of knee. Such method is traumatic, expensive and complications prone and revision of artificial joint after surgery. At the same time, complete application of HTO is tissue regeneration of chronic distraction and external fixation assisted in computer for treating severe KA has effective and exact control on the angle of HTO, patient recover quickly, low volumes in bleeding, postoperative ability of adjustment, surgical trauma at low levels and so on [10].
HTO is best option in physically active and younger patient with loss of symptomatic cartilage and malalignment of varus [11]. Though, HTO has revision rate of nearly thirty percent at 10 years, attributable either to arthrosis development in patellofemoral or laternal compartments or arthrosis progress in compartment of medial tibiofemoral [11] [12].
Presently only option for revision for failed HTO is TKA (total knee arthro-  Malahias et al. [35] pointed out that patients with deficient varus angulated knee-anterior cruciate ligament (ACL) require isolated HTO as well as extra ACL reconstruction. From the findings of the investigation, it was found that ACL reconstruction and one stage HTO is efficient and safe procedure to treat the patients who suffer from symptomatic varus osteoarthritis to combine with instability of anterior knee. Cao et al. [36] and Takeuchi et al. [37] [46]. Hui et al. [7] compared patients older and younger than fifty years and identified hazard ratio of 3.7 percent among patients above 50 years. When carrying out multivariate analysis, age was found to be main factor of patients who undergo arthroplasty with 8 percent high risk for increasing age at every one year. However it is not clear that what cutoff of age could be adopted, high rise in rates of failures likes to happen in age group of 50 to 60 years. Older patients who decide to do HTO surgery have to consider all risk factors. It was noted that impact of age on revision when compared with OA preoperative diagnosis is very less and therefore severity of the disease and physiological age are better signs of revision instead of preferring complete biological age.
Pannell et al. [47] identified 1576 procedures from 2000 to 2014, among these 358 procedures were changed to arthroplasty during ten years. It was found that older patients who undergone arthroplasty after surgery HTO had great frequency of hypertension and great likelihood of getting comorbidity. Furthermore, it was noted that patients were 8 percent would need arthroplasty for every other year in age. It was noticed that female patients were under high conversion risk to arthroplasty than male patients. Apart from these, survivorship at 10 and 5 years was 56 percent and 80 percent respectively and failure rate's median time was 5.1 years. Long-term survival was seen among selected patients who undergone HTO. Careful observations have to be provided to patient sex, age and KO when patients decide to undergo this procedure.
Kumar et al. [48] conducted single centre and interventional research was performed on 60 patients were radiologically and clinically diagnosed as varus deformity KO. After assessment of proper pre-operative one, patient had undergone HTO. Outcomes in terms of clinically were estimated with functional score and score of knee society. At regular intervals, follow-up was done for patients during third, sixth and 12 th month. Mean functional score and knee score of preoperative mean for patients' prior operation were 53.22 percent and 54.3 percent respectively. Functional score and knee score at 1 year was found to be 81.5 percent and 82.3 percent respectively. Thus comparison score of postoperative and pre-operative indicated statistically important enhancement in functional and knee society score. From the findings of the investigation, it was found there was major rise in functional score and knee score after HTO for patients of varus deformity KO. Thus HTO must be suggested for degenerative arthritis treatment of knee in active, young patients for symptomatic enhancement and activity levels maintenance. HTO is adopted for physically active and young patients with KO. Such pa-

Open Wedge HTO
Yokoyama et al. [50] recommended that impact of OWHTO emerged in three months and average period for healing was 6.3 months. This research evaluated 47 patients who undergone OWHTO treatment. Women and patients with high body mass index would like to have a much time to heal. Such facts are taken into consideration when selecting suitable method for surgery and have to be shared with patients with degenerative gonarthrosis of medial type since this could be main data for patients for deciding whether to undertake OWHTO. Prospective interventional research in hospital was carried out on 30 patients of varus deformity osteoarthritis. All 30 patients were properly assessed the form of pre-operative surgical intervention in HTO was carried out and result was estimated using scoring system of knee society. This research has revealed that HTO for patients with UCO (Unicompartmental osteoarthritis) would reduce the pain as well as maximize the functional and knee score. Suitable selection of patient, exact types of osteotomy and exact surgical techniques are important for HTO success. It was also found that successful result of HTO is maintained for eight to ten years thus delay the necessity for conversion to arthroplasty of total knee. Thus HTO are suggested for treating the knee's degenerative arthritis among young patients [51].
OWHTO is an expanded method to treat the patients with MCO (medial compartment osteoarthritis) and VM (varus malalignment). For these patients, HRQL (health-related quality of life) are enhanced by adopting such procedure. 120 patients were selected for this research who undergone OWHTO without a graft of bone with the TomoFix TM plate. Mental component score for lower preoperative outcomes in minimized postoperative clinical result and extended time of inability for work after OWHTO. On the other hand, score of physical component exhibit comparable values to usual inhabitant already six months after OWHTO [52]. [33] [45] [46] stated that HTO is best suitable for treating the young patients.
Age was found to be main factor for selection of HTO patient. Bonasia et al. [53] examined 99 OWHTOs patients and it was identified that age was main factor, probably failed operation was 5 times highest in patients aged greater than 56 years which indicate there must be necessity to again consider the range of age. Results are consistent with the findings of [45]. It was revealed that medial OWHTO would influence the patellofemoral joint (PJ). Some of the researchers have opined that medial OWHTO result in patella baja, thus lead to maximized pressure in patellofemoral contact [54] [55] [56]. In addition to these, some researchers have investigated about that impact of medial OWHTO on PJ with the help of arthroscopic assessment. It was found that overall decline in PJ at articular cartilage over time with the help of medial OWHTO [57] [58] [59] [60]. Open Journal of Orthopedics Moon et al. [61] examined over 92 patients with medical OWHTO and proceeding by assessment of 2 nd -look arthroscopic. Patients were categorized into 2 groups. Comparative analysis was carried out with respect to measurements of arthroscopic, radiographic parameters and clinical scores among two groups.
From the outcomes of clinical result, it was indicated overall enhancement from baseline to 2 nd -look operation time, with no major variance between 2 groups. In radiographic parameters, no significant variances were found among two groups.
Patellofemoral osteoarthritis in terms of radiographic grade in both groups in- High EKAM (external knee adduction moment) is a replacement assessment of medial loading of knee, thus correlates greater with internal forces of medial contact in initial stance [63]. OWHTO minimizes initially elevated high level of EKAM which is minimal when compared with noticed control subjects [64] [65] [66].
Dragosloveanu et al. [67] determined that there was no significance between after slope of surgery tibial and preoperative varus whereas posterior inclination after HTO impacts the slope of tibial posterior at two years. Correction degree has strong impact over reduce or increase in slope of tibial posterior. A rise in tibial slope maximizes the flexion in the knee by 1.45 degree for each inclination degree. Moghtadaei et al. [68]

Closed Wedge HTO
Soleimanpour et al. [70] identified a statistically related difference between closed wedge HTO and OWHTO. It was clear that OWHTO was significant in operation length, duration of weight-bearing and return to normal lifestyle. Prognosis of single and integrated HTO with other procedures was studied. It was found that postoperative follow-up after 2 years, prognostic survival was best in terms of OWHTO when compared with CWHTO [71]. OWHTO

Conflicts of Interest
The authors declare no conflicts of interest regarding the publication of this paper.

Funding Source
Funding is fully supported by Department of Orthopedic surgery, Zhongda Hospital affiliated to Southeast University.