Surgical Options for Treating Knee Osteoarthritis-A Concise Review

Several options are available to manage osteoarthritis of the knee including arthroscopic joint debridement, high tibial osteotomy, proximal fibula osteotomy, Maquet osteotomy, joint distraction procedure, sub-chondroplasty, injection of platelet rich plasma, injection of stem cell, patellofemoral arthroplasty, unicompartment knee arthroplasty, and total knee replacement. The choice of surgery will depend on location and severity of the osteoarthritis, age, comorbidities, and body mass index of the patient. The aim of this review is to provide an overview of the available surgical treatments for knee osteoarthritis.


Background
Osteoarthritis (OA) of the knee joint is an extremely common condition seen in our daily practice with reported prevalence of 30% in people over 60 years of age [1]. It is the fourth leading cause of disability the world-over [2,3].
The guideline for non-surgical management of OA was published in 2007 by OARSI (Osteoarthritis research society international), which have been refined based on systematic reviews [4]. There have been published pathways, evidence based guidelines and appropriate proved surgical techniques, better implants, and fixation techniques, a renewed interest has been found in this procedure [15][16][17]. It is recommended for physiologically young and active patients meeting the criteria mentioned in Table 2. Presence of advanced degenerative changes, inflammatory arthritis, and large areas of exposed bone are contraindications to the procedure [18]. The aim of this osteotomy is to over correct the mechanical alignment to 3-5 deg of valgus [14,19,20]. The correction can be achieved by either a lateral closing, medial opening or dome shaped osteotomy [21,22]. The required amount of wedge to be removed is determined pre-operatively using a technique described by Fujisawa [23]. The osteotomy can be fixed using a spacer plate (Puddu), Locked plate (Tomofix) or a dual sliding compression plate ( Figure 1)

Recommendation at present
There is limited available evidence to recommend HTO for treating pain from knee medial compartment OA.

Proximal Fibular Osteotomy
Fibula acts as a strut to load 1/6 body weight and prevents uniform settling of osteoporotic proximal tibia [26]. This contributes to increased stress on medial tibial plateau and development of varus osteotomy. Proximal fibular osteotomy redistributes the loading of tibial plateau and relieves pain ( Figure 2) [26-28]. Only few short term studies are available [26,28,29]. The improvement in post-operative score depends upon inclination and OA of proximal tibiofibular joint, BMI and pre-operative knee function [28].

Maquet Osteotomy
First proposed by Maquet in 1963 and aimed to unload painful patellofemoral (PF) joint by tibial tubercle anteriorization [30,31]. Generally, patellofemoral pain from severe PF osteoarthritis not responding to non-operative treatment is the primary indication for this procedure.
The Maquet technique relieves anterior knee pain by decreasing contact load on the PF joint by elevating tibial tubercle [30][31][32]. A bone block, either autograft or allograft, inserted beneath the tibial tubercle to maintain crest elevation ( Figure 3). It provides a good short and long term results in 80% of the cases [33,34]. Progressive anteriorization of the tibial crest is associated with progressive decrease in the PF compressive force [32]. However, only 1.5 to 2 cm of elevation is recommended as further elevation result in minimal compressive relief [35]. Reports of this procedure had good result; however, skin necrosis and graft nonunion are the main local was possible for patients to develop thromboembolism (0.5%) and infection (0.2%). They strongly recommended against arthroscopic knee surgery in patients with degenerative knee disease [12].

Recommendation at present
There is no role for routine lavage or debridement for patients with radiographic OA. However, patients with clicking or locking may be offered this procedure for improvement in mechanical symptoms only along with possible associated risks.

High Tibial Osteotomy (HTO)
This procedure was described by Jackson in 1958 and popularized by Coventry [13,14]. There was loss of interest in the procedure subsequently, but with im-

Knee Joint Distraction -Arthrodiastasis
It works on the principle of unloading of the medial tibial compartment. It was first described in 2010 as a case report and subsequently used for management of knee OA [36,37]. There was a study mentioning that the thickness of cartilage formed after this procedure was better than HTO [38]. A randomized control trial comparing knee joint distraction with HTO found no difference between the two techniques in regards to joint space widening and clinical outcome [39]. It may be considered as an alternate option for medial compartment OA in patients with minimal leg malalignment.

Recommendation at present
There is a lack of strong evidence on the efficacy of this procedure in treatment of knee OA. Well designed comparative trials in this subject are needed for evaluation of its benefit.

Sub-Chondroplasty
It is minimally invasive procedure described for knee OA patients with bone marrow edema ( Figure 4). These patients have been shown to have accelerated progression to painful OA [40,41]. This technique involves fluoroscopic control and application of calcium sulphate based bone substitute. Early results (2-4 years) have shown relief in pain with improved structural quality and remodeling of bone [42][43][44]. Longer term studies and controlled trial are required before it can be included in the guidelines.  The indications and contraindications for PFA are summarized in Table 3. Total knee replacement (TKR) with patellar replacement is the gold standard for treating advanced PFOA due to long term good result [58]. However, meta-analysis of 28 studies revealed comparable results in function and complications rate between TKR and modern generation PFA in short and mid-term results [59].

Unicompartment Knee Arthroplasty
There has been more interest in this technique recently, although it was described initially in 1970 [60]. Medial compartment is more commonly involved and unicompartment knee arthroplasty (UKA) comprises 11% of total arthroplasty cases of knee joint (UK joint registry). It was classically indicated for elderly > 60 years low demand and thin patients (weight < 82 kg) [61]. The indications have been extended to younger patients by oxford group (Cite -oxford knee) as a result of better surgical technique, better prosthesis design and improved polywear [60][61][62]. Historically ACL deficient knees have shown early failure after UKA due to eccentric loading and polywear. Recent studies have divided ACL deficient knees into two subgroups; traumatic and degenerative. UKA should not be done in patients with traumatic, symptomatic ACL rupture. Although satisfactory results have been reported in these by combining ACL reconstruction with UKA [63,64]. The other group of patients with degenerative tear of ACL should have a posterior slope < 7 degrees [65].
UKA has been successful in middle aged patients with > 90% survival at 10 years, with excellent function (Figure 5) [66,67]. In comparison to total TKR, UKA provides faster rehabilitation and quick recovery, less morbidity, and less blood loss. It also preserves normal kinematics of the joint. This procedure should be avoided in conditions shown in Table 4.

Platelet Rich Plasma (PRP)
Concentrates obtained from blood releases various cytokines which help in cartilage regeneration and reducing synovial inflammation [45]. Early results (1 year) of PRP injection are better than Hyaluronic acid/placebo without any additional risks [46,47]. It is recommended to make shared decision with the patient [48].

Recommendation at present
There is inadequate evidence on the efficacy of this procedure in relieving OA knee pain. However, there is no known major harm of using PRP.

Stem Cell
Pleuripotent mesenchymal stem cells help in replacing lost cells. They release trophic factors which help to reduce inflammation and stabilize matrix [49]. Randomized control trials comparing stem cells injection with conservative treatment have shown improved function at 12 months and a lot of future studies are anticipated in this modality of treatment [50][51][52][53].

Patellofemoral Arthroplasty
Patellofemoral arthroplasty (PFA) introduced by Mackveer in 1955, but initial design was associated with poor functional results [54]. However the current modern design has produced good results and outcomes with ten years survivorship of more than 80% [55]. Patient selection, implant designs, and surgical technique are the main factors for achieving better outcome. The main indication for PFA is advanced isolated OA of knee   [68]. It can be safely said that a conventional knee can be performed by an approach familiar to surgeon, using standard well established components, with or without tourniquet and without drains to achieve good long term results [68].

Conclusion
Surgical option should be considered to manage OA knees only after exhausting conservative options. The treatment offered should be modified based on patient age, demands and symptoms. HTO and UKA are considered in single compartment disease and total knee should be reserved for end stage disease. A realistic expectation should be offered to the patient based on available evidence to have a satisfied patient.

Declarations Ethical consideration
This is a review article that does not involve patients or patient's information.

Financial support and sponsorship
Nil.

Conflicts of interest
There are no conflicts of interest.

Authors' contributions
JSL conceived and designed the article's outlines and wrote the initial and final draft. SAH contributed with draft writing, organized and prepared the figures, and was the corresponding author. SUG: Reviewed the final Total Knee Replacement TKR is indicated for end stage OA ( Figure 6). A 25 year survival rate of 82% has been reported (95% CT -83-83.2) [68]. But despite this, one out of five patients are still not satisfied after surgery [69]. The aim of the procedure is to restore mechanical alignment, joint line, and achieve normal balanced ligaments with restored angle. The joint can be approached using either a medial parapatellar, mid vastus or subvastus approach. Better early outcomes were reported subvastus and midvastus approach but in long term there was no difference between two groups [70][71][72]. Coronal plane alignment is achieved by precise bone cuts, releasing of tight medial ligaments and tightening of lax lateral side. The saggital plane alignment is achieved by tackling tibia in symmetric gap mismatch and femur in asymmetric gap mismatch. There is no difference in clinical results between posterior cruciate retaining and stabilized implants [73,74]. The implant fixation (cemented/uncemented) bearing surface (mobile/fixed) and alignment