Bilateral genu varum deformity correction in an adult by medial opening-wedge high tibial osteotomy without internal fixation

Abstract

A young adult man in 20s presented with bow leg deformity of both the knees, since childhood and bilateral knee pain for the last 4 years. Plain radiographs of both the knees confirmed bilateral genu varum deformity, more on the right side (16.2°) as compared with left (12.3°). He was managed surgically by a single-stage bilateral medial opening wedge high tibial osteotomy, using a synthetic bone substitute of a tri calcium phosphate. After the healing of osteotomies at 3 months, the patient was pain free and walked comfortably with normal lower limb alignment.

Background

Genu varum deformity resulting is relatively uncommon in younger adults.¹ Symptomatic deformity in young individuals is challenging to manage; more so if there is bilateral involvement. A joint preservation technique like a corrective osteotomy is a useful and attractive option here.²

High tibial osteotomy (HTO) is a popular treatment option for medial compartment cartilage loss or OA with concurrent varus deformity. HTO displace the lower limb’s load-bearing axis laterally and causes a postoperative valgus limb alignment, thus realigning the weight-bearing line in the coronal plane, from the arthritic compartment to the healthy tibiofemoral compartment. Load reduction in the diseased compartment relieves knee joint pain and slows the progression of OA.³

We present a case of a young adult with symptomatic genu varum deformity, which was managed by a single-stage bilateral HTO (medial open wedge). It is conventional and a routine practice to use metallic implants to fix an HTO, but this case has a novelty that no metallic implants were used here.

Case presentation

A young adult man in 20s presented with deformity of both knees since childhood (due to rickets), and developed bilateral knee pain for the last 4 years, which has been increasing progressively. He denied any history of trauma. He was on conservative management like physical therapy, non-steroid anti inflammatory drugs, for his knees pain. His activities of daily living were being now affected due to knee pain. He was an average-built adult, with a normal bone mass index. There were no associated medical comorbidities. Local examination revealed a bilateral genu varum deformity of 15° (figure 1). The knee movements were painful terminally and there was no ligament laxity.

Figure 1.

Preoperative clinical photograph of both lower limbs showing bilateral genu varum deformity of both the knees.

Investigations

Plain radiographs (anteroposterior and long leg alignment views) of both lower limbs confirmed bilateral genu varum deformity (figure 2). The mechanical axes of both lower limbs were shifted medial to the centre of the knee with varus more on the right side (16.2°) as compared with the left (12.3°). The centre of rotational angulation was at the junction of metaphysis and diaphysis. The tibial metaphyseal-diaphyseal angle on the right side was 10.2° and on the left side, it was 9.2°.

Figure 2.

Preoperative long leg alignment radiograph (anteroposterior views) showing bilateral genu varum deformity. Varus is marginally more on the right side (16.2°) as compared with left (12.3°).

Differential diagnosis

All the likely causes of genu varum deformity in young adults must be considered as a differential in making a diagnosis such as Blount’s disease, sequelae of vitamin D deficiency, osteomyelitis and post traumatic. Less commonly, it can be associated with osteogenesis imperfecta, achondroplasia, Paget’s disease and Turner’s syndrome. These conditions have specific clinical features which are crucial in differentiation with each other. Vitamin D deficiency and Paget’s disease also have biochemical abnormalities like low vitamin D and high Alkaline phosphate levels.

Treatment

The treatment options were discussed with the patient in detail, and all the pros and cons were explained about them. He opted for a bilateral (single-sitting) procedure due to his logistic reasons. After obtaining informed consent, he was managed with a single-staged bilateral HTO (medial open wedge), using a synthetic bone substitute of tri calcium phosphate (TCP). No metallic implants were used for internal fixation of the osteotomy.

Preoperative planning for the deformity correction was done based on the long leg radiographs. It was calculated that 8° of valgus correction is needed. The surgery was done under spinal anasethesia using pneumatic tourniquet and an image intensifier. A 7 cm long vertical incision was made over the upper medial tibia, centering over the tibial tuberosity and 1 cm medial to it. The periosteum was eleveated and a curved Langenbeck retractor was placed over posteromedial shaft of the tibia. A guide was inserted into the upper tibia in the intended line of osteotomy, from medial side at the level of tibial tuberosity, aiming towards the head of fibula, under X-ray control. An osteotomy was then made parallel to the guide wire from medial to the lateral side, just short of lateral cortex. The osteotomy was completed with the sharp osteotomes ensuring that the contralateral cortex is not breached or osteotomised. The osteotomy was then opened up with a valgus stress and gradual dilatation of it was done using special dilators from 6 mm to 8 mm (as per preplanning). An 8 mm TCP wedge was then impacted into the osteotomy gap, with a rubber punch in and hammer, in extension. Finally, the stability of osteotomy fixation of the osteotomy was checked on image intensifier.

Outcome and follow-up

Postoperatively, a knee-immobiliser splint was used for 2 weeks, and then knee flexion was started. He was mobilised in a wheelchair for 6 weeks followed by mobilisation with a walking frame for another 6 weeks and then full weight-bearing was permitted at 12 weeks. At 6 months follow-up, he is pain free, able to mobilise without support, and osteotomy was healing well (figure 3). He was comfortably sitting cross-legged and was able to squat (figure 4).

Figure 3.

Postoperative plain radiographs of both the knees (anteroposterior and lateral views) and long leg alignment (anteroposterior) radiograph (at 3-month follow-up), showing normal lower limb alignment, healing osteotomy and a well-placed tri calcium phosphate wedge at the osteotomy site.

Figure 4.

Postoperative clinical photographs at 3-month follow-up, showing normal lower limb alignment, complete knee flexion and sitting in cross-legged position.

Discussion

HTO is a useful and effective treatment modality for medial compartment knee OA, with symptomatic varus deformity, especially in younger people. Various operative techniques are described and used for the HTO; the most popular being an opening wedge osteotomy.^{4 5} The medial open wedge osteotomy (MOWHTO) offers several advantages like restoring the height of the medial column, not significantly altering the tibial slope and patellar height, easy to convert to TKA, no fibular osteotomy required, and no restriction of activities needed,^{6 7} as with arthroplasty. A MOWHTO is mostly fixed with different types of commercially available plates. Their use may result in some problems like increased cost and risk of infection, future TKA necessitates implant removal, larger skin incision and soft-tissue dissection are required for TKA. In addition, MRI may be difficult to perform, and interpreting the presence of an internal fixation device may interfere with the ACL reconstruction tibial tunnel.

We present a novel technique of performing the MOWHTO without using any metallic implants. This technique can be performed in most cases with mild-to-moderate genu varum deformity (<10°), without any hardware by using a beta-tricalcium phosphate (TCP) wedge and achieving satisfactory alignment and functional results.^8–10 This procedure avoids the likely problems associated with the use of metallic implants. These TCP wedges are bioabsorbable and anatomically contoured implants, which are bioactive, and gradually release calcium and phosphate ions into the milieu interior. This results in new bone formation at the osteotomy site. The porosity of the TCP wedges varies, from 30% to 70%. The porous structure acts as an osteoconductive conduit for the osteoblasts proliferation and neovascularisation. Over time, the porosity of the wedges is slowly replaced by viable bone and results in complete incorporation of the wedge. Van Hemert WL et al have described five stages of bioabsorption of TCP wedges; a healed osteotomy is seen in the osteoblastic phase, when a distinction between TCP and bone is slightly visible, and a full reformation with a recognisable osteotomy site is seen in the consolidation phase, when the TCP is fully incorporated biologically with no visible osteotomy in the last stage.¹¹

Whereas, the non invasive or lesser invasive options of joint preservation like knee braces, arthroscopic procedures are effective only in early OA, and not is moderate or severe knee deformities, whereas arthroplasty if often avoided in younger age group because of the likelihood of future revision surgeries. An HTO aims to alleviate knee pain by shifting weight-bearing loads to the relatively unaffected lateral compartment in varus knees and to postpone the need for a knee replacement by retarding medial joint compartment degeneration.⁴ However, proper patient selection and precise surgical planning are crucial.^12–14 Younger (<65 years) and active individuals with symptomatic mild to moderate varus knee deformity (<10°) are considered ideal candidates for HTO.^15–17 El-Ganjoury et al reported that the HTO provides a better range of motion than the unicompartmental arthroplasty and is especially beneficial for people who require a lot of activity,¹⁸ whereas UKA is better for older patients due to shorter rehabilitation time and faster functional recovery.^{19 20}

We did bilateral single-stage MOWHTO in this case, and found it to be effective and a safe procedure. Hernigou et al compared the safety of a simultaneous bilateral HTO with staged bilateral HTO, in 35 and 55 cases, respectively, and found that the simultaneous bilateral HTO was a good treatment option. We agree with the authors that the individuals who undergo staged bilateral HTO face the risk of complications twice, in addition to two hospitalisations and prolonged treatment period and off from work. However, cases that undergo simultaneous bilateral HTO may have a higher chance of blood transfusion.²¹ Neirynck et al compared the outcome of simultaneous bilateral HTO with unilateral HTO in 29 cases and concluded that simultaneous bilateral HTO provides similar clinical outcomes as unilateral HTO and does not take an excessive amount of time to achieve these outcomes. When compared with two-staged surgery, they revealed it to be a safer and more effective treatment approach for those suffering from bilateral medial knee OA and varus alignment.²²

Patient’s perspective.

I had deformity in my both knees since childhood and pain in both knees during walking since 4 years. But now I am extremely happy with the outcome of my treatment. Now, I have normal legs alignment and also able to walk pain free without support. I can do comfortably sitting cross-legged and squatting. This has helped me to do my activities of daily living independently.

Learning points.

• Bilateral genu varum deformity in young adults is uncommon, and is challenging to manage. On the other hand, these deformities are common in older people with osteoarthritis.

• A corrective high tibial osteotomy (HTO) is advisable to prevent osteoarthritis and to address the pain (if present).

• We achieved a successful outcome in an adult male with symptomatic genu varum deformity, after performing a bilateral medial open-wedge HTO in a single sitting.

• Fixation of HTO with a metallic implant is not necessary in all the cases (especially with mild to moderate degrees of deformities) and insertion of a tri calcium phosphate wedge (synthetic bone graft) into the osteotomy site is sufficient in both younger and older patients.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s)