Osteoarthritis (OA) of the knee is joint damage, resulting in pain accompanied by varying
degrees of functional limitation and reduced quality of life. 20% of adults over 50 and 40%
over 80 years report disability from knee pain secondary to osteoarthritis.The majority of
patients present to primary care with symptoms of pain and stiffness, which reduces mobility
and with associated reduction in quality of life, with many patients not requiring surgery,
with their symptoms adequately controlled by non-surgical measures. When patient's symptoms
are not controlled by up to 3 months of non-operative treatment they become candidates for
assessment for joint surgery. There are a number of surgical (Arthroscopy, Total/Partial Knee
Replacement, High Tibial Osteotomy) and non-surgical (including exercise, weight loss, manual
therapy, oral medication, injection therapy, splints and braces) options available. The
decision to undergo surgery is based on patient symptom pattern, with the type of surgery
determined by the pattern of joint damage and the patient's preference. High Tibial Osteotomy
(HTO) should be considered primarily for patients with varus mis-alignment in medial
unicompartmental osteoarthritis of the knee as the main indication for the procedure. HTO
involves removing or adding bone to realign the limb and offload the knee. It is effective
and can provide functional outcomes similar to those seen after joint replacement. HTO is a
commonly used surgical procedure and has wide appeal because of the preservation of the knee
joint. The principal advantages of opening wedge high tibial osteotomy include maintenance of
the bone stock, correction of the deformity close to its origin, and no requirement for a
fibular osteotomy. Although it is a good option for young patients with isolated medial
compartment OA and varus deformity, it can be done even for older active people over 65. By
preserving the patient's own knee anatomy, a successful osteotomy may delay the need for a
joint replacement for several years. Another advantage is that there are no restrictions on
physical activities after an osteotomy, even high impact exercise.
Contemporary Surgical approaches to HTO can often utilise bone graft substitutes to improve
patient outcomes. Bone grafting in open wedge high tibial osteotomy (HTO) is an area of
clinical research that requires further evaluation. While open wedge high tibial osteotomy
(OWHTO) with medial plate fixation is a proven adequate and safe method for treatment of
medial compartment osteoarthritis of the knee and varus deformity, particularly in young
and/or active, it nevertheless creates a gap in the metaphysis of the tibia. To enhance bone
healing and increase initial mechanical stability, a high degree HTO may require the
application of bone graft/substitute to fill the osteotomy gap. Moreover, HTO has been
associated with risk of nonunion, collapse and loss of correction. Autologous bone graft is
the "gold standard" to fill the bone defect, but iliac crest graft harvest has risks. The
associated complications include pain, thigh hypoesthesia, infection, pelvic bone fracture
and discomfort wearing clothes. Allograft is commonly used to avoid the risks of
autografting, such as donor side morbidity. However, the use of allograft increases
additional risks such as disease transmission, immunologic reactions and slow remodelling.
Due to the limited autologous bone availability and the problem of donor-site morbidity, many
efforts have been made to find adequate supporting material for augmentation after osteotomy.
Hydroxyapatite, β-tricalcium phosphate or the combination of both are the most commonly used
synthetic augments in HTO. However, the most suitable material for filling the opening space
in OWHTO has not been conclusively identified. While HTO with and without bone grafting has
been assessed as radiologically equivalent, of particular interest to clinicians and patients
is the contention around the secondary outcomes (site morbidity and bleeding, chronic pain,
patient discomfort long term) which are frequently a challenge in postoperative management of
patients. Autologous bone graft would still be the best choice for a lot of applications
where bone grafting is needed but there are many disadvantages - the relatively high donor
morbidity and the limited amount which can be harvested - which will eventually lead to a
very restricted use of it. Allografts do not have these limitations, but in the form of
demineralized bone matrix they have very variable osteoinductive properties and can possibly
transmit diseases. Synthetic 2nd generation biomaterials have a long and safe history of use
but do not provide a compelling alternative to traditional bone grafting. 3rd generation
biomaterials as bone graft substitutes, such as HydroxyColl, offer exciting prospects of
improved patient clinical outcomes and may provide a viable alternative to autologous bone
grafts. Treatment for these patients would be with Open Wedge High Tibial Osteotomy with
medial plate fixation. Over the period of the trial, adverse events will be reported by the
study centre and it will be the prominence or absence of these, along with blood inflammatory
marker evaluations that will determine the inherent safety of Hydroxycoll compared to the
standard of care. At each follow up visit x-rays will be performed and evaluated by a
certified radiologist. Site morbidity and bleeding will be clinically assessed. They will
report and assess the radiographic images determining if healing has occurred. Along with the
clinical assessment, the surgeon or a member of the clinical team will determine extent of
healing. Patients will also self-report a number of key pain, mobility and post-operative
joint inflammation outcomes.
The study is a single centre randomized blinded study to assess the efficacy and safety of
Hydroxycoll bone graft substitute used as a bone graft substitute in Open Wedge High Tibial
Osteotomy with DePuy Synthes TomoFix Medial High Tibial Plate (MHT) fixation (Standard of
Care). This study has been designed to last for 52 weeks with follow up visits post surgery,
6 weeks, 12 weeks and a final follow-up at 52 weeks. In case of AEs/SAEs ongoing when the
patient has completed the study, the patient will be contacted by phone one month after study
completion for follow-up. The study will have 2 arms with 20 subjects per arm, each receiving
at the time of surgical intervention either; 1) Open Wedge High Tibial Osteotomy with medial
plate fixation (without bone grafting). 2) Open Wedge High Tibial Osteotomy with medial plate
fixation (with bone grafting) using Hydroxycoll bone graft substitute. An Independent Review
Board (IRB) will approve the protocol before the study begins. A clinical monitor selected by
SurgaColl will monitor the trial. Any serious adverse events (SAE) will be reported as soon
as possible (within 48 hours of awareness) to SurgaColl by the study centre. SurgaColl will
communicate the SAE to all relevant authorities.