Condition category
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status

Plain English Summary

Background and study aims
In osteoarthritis, tissues where two bones make contact in the knee joint become damaged or worn away and walking can become painful or uncomfortable, sometimes with a feeling of grinding or catching in the knee. The whole knee joint can be replaced with artificial components to treat knee osteoarthritis, but this is a serious surgery that can take a long time to recover from. In younger patients (aged 55 to 64 years) it is likely that the knee replacement might need to be redone after about 10 years. High tibial osteotomy (HTO) is a simpler surgery that aims to realign the knee joint of there is wear on one side more than the other. It involves inserting a wedge into the tibia (shin bone) near the knee joint in order to move the force involved when a person is walking onto the healthy side of their knee joint. This surgery can delay the point where a knee replacement is necessary by 8-10 years.
In HTO, a metal plate is used to hold the wedged-open tibia in place while the bone heals, which takes up to a year. This plate can be left in place afterwards, but some patients experience discomfort from the plate and need another operation to remove it. This study aims to compare two HTO plates to see if one results in less pain after surgery or fewer removal operations.

Who can participate?
There will be no open recruitment for this study. Patients scheduled to undergo HTO at the study hospital will be asked if they would like to participate.

What does the study involve?
Participants will be randomly allocated to receive one of the two HTO plates. They will not know which one they have received. The surgery will be carried out as normal, other than which plate is used. After surgery, participants will be asked to rate their pain for the first 5 days. They will come to the outpatient clinic at 2 weeks, 6 weeks and 1 year after surgery for routine assessment. At 2 years after the surgery, they will be sent a questionnaire asking whether they have had the plate removed or are scheduled to have it removed.

What are the possible benefits and risks of participating?
There are no risks involved to the research participants as the treatment they receive will not differ to their standard care. The two plates are both CE-marked, which means they are considered safe, and they are both on the market. There is no potential benefit for the participant other than the contributing to better healthcare for future patients. Qualified and experienced members of the research team will ensure that participants are carefully managed to maintain safety and comfort for the duration of the study

Where is the study run from?
North Bristol NHS Trust (UK)

When is the study starting and how long is it expected to run for?

Who is funding the study?
Newclip Technics (France), which produces one of the plates used in this study, and the UK National Institute for Health Research (NIHR)

Who is the main contact?
Mrs Rachel Bray,

Trial website

Contact information



Primary contact

Mrs Rachel Bray


Contact details

Clinical Research Centre – Bristol Knee Group
North Bristol NHS Trust
Southmead Hospital
BS10 5NB
United Kingdom
+44 (0)117 4148131

Additional identifiers

EudraCT number

Nil known number

Nil known

Protocol/serial number

CPMS 34888, IRAS 211393

Study information

Scientific title

Removal of metalwork following high tibial osteotomy: A randomised controlled trial comparing removal of metalwork rates for the ActivMotion (Newclip) and Tomofix (Synthes) high tibial osteotomy plates



Study hypothesis

This study aims to compare two different plates currently used in high tibial osteotomy (HTO) surgery (knee realignment). The purpose of the metal osteotomy plates is to maintain the correct realignment achieved at surgery whilst the bone heals. The TomoFix and ActivMotion plating systems are both used in current practice and comply safety regulations.

Once the correction has healed (approx. 12 months) the plate can be left in. Some patients may however experience discomfort related to the plate and benefit from plate removal, about a year after their initial operation. The ActivMotion plate design is a smaller than the Tomofix and it is therefore potentially less likely to cause discomfort. It is anticipated that second operations for plate removal will be less frequent than for the Tomofix plate.

A small cohort study (Tomes et al. Unpublished data) suggested that plate removal rates may be much lower – 5%. However there has been no comparative study. In this study we would like to compare the number of plates that need removal following surgery, assess pain levels in patients in the first 2 years following surgery and compare the amount of analgesia used in the immediate post-operative recovery period.

Patients who will be asked to participate are those about to have a high tibial osteotomy. Participants will be asked to complete a questionnaire before they have their operation and 12 months after the operation to assess their pain and function. They will also be asked to record their pain levels before their operation, for 5 days after their operation and at each of their routine follow ups (2 and 6 weeks and 12 months). The amount of analgesia participants use will be recorded in the initial post-operative period. This information will be used to compare the outcome of the plates.

Ethics approval

Approved 26/07/2017, London - West London & GTAC Research Ethics Committee (The Old Chapel, Royal Standard Place, Nottingham NG1 6FS; +44 (0)207 104 8007;, ref: 17/LO/0896

Study design

Randomised; Interventional; Design type: Treatment, Surgery

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

No participant information sheet available


High tibial osteotomy (HTO) for knee realignment


This is a randomised controlled trial comparing two high tibial osteotomy plates - both currently used in standard practice and both CE marked. The research nurses working on the study will follow a Standard Operating Procedure (SOP) to complete randomisation using block randomisation via sealed numbered envelopes. The randomised treatment will be recorded in the patient’s hospital notes plus study notes, and the surgeon will be notified. Patients will be blinded to their allocation treatment.

20 patients will be recruited to each arm at one NHS Trust site. The study duration comprises 2 years recruitment and 2 years follow up.

At the pre-operative visit, a baseline assessment of pain will be recorded and the KOOS score will be used to record baseline pain, quality of life and function.

On the day of surgery, leg circumference and wound measurements will be taken at the end of the operation.

On Days 1-5 post-surgery, pain levels will be recorded by patients at home for 5 days following surgery using a Visual Analogue Score (VAS). The research team will contact participants by telephone on day 1 and day 4 to provide support with this process. Patients will then use pre-paid envelopes to return their VAS scores to the research team.

At the Week 2, Week 6 and Month 12 visits, participants will be seen in the outpatient clinic. VAS pain scores will be recorded at each visit. A KOOS score will be recorded at 12 months.

A postal questionnaire will be sent to patients at 2 years following surgery to establish whether they have had their plate removed or have been listed for plate removal.

The X-rays performed for this study are the same as those performed in standard care and routine treatment for patients with this condition.

Intervention type



Not Applicable

Drug names

1. TomoFix
2. ActivMotion

Primary outcome measure

Proportion of participants requiring removal of plate or listed for plate removal within 2 years of surgery assessed using a questionnaire posted to participants

Secondary outcome measures

1. Pain assessed using a visual analogue score (VAS) at 1-5 days, 2 weeks, 6 weeks and 1 year post-operatively
2. Pain associated with knee osteoarthritis assessed using the Knee Osteoarthritis Outcome Score (KOOS) score at baseline and 1 year
3. Knee function assessed using the KOOS score at baseline and 1 year
4. Quality of life related to knee problems assessed using the KOOS score at baseline and 1 year
5. Wound size assessed using the measurements of the circumference of the limb and the wound
incisions taken at the time of surgery.

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Standing varus malalignment benefitting from high tibial osteotomy correction
2. Diagnosed with current osteoarthritis of the knee
3. Aged over 18 and under 65 years
4. Candidate to be implanted with a Tomofix or ActivMotion plate
5. Understands and accepts the obligation to comply with the required follow-up visits and is logistically able to meet all study requirements
6. Has signed informed consent for the use of their personal private data

Participant type


Age group




Target number of participants

Planned Sample Size: 40; UK Sample Size: 40

Participant exclusion criteria

1. Has declined to sign informed consent for the use of their person /private data
2. Correction greater than 14 mm opening wedge
3. Flexion contracture greater than 15°
4. Knee flexion under 90°
5. Medial/lateral tibial subluxation over 1 cm
6. Medial bone loss of over 3 mm
7. Inflammatory arthritis
8. Arthritis in the lateral compartment
9. Patella baja
10. Weight over 110 kg
11. Severe patellofemoral symptoms
12. Unaddressed ligamentous instability
13. Fixed flexion contracture
14. Known or suspected osteoporosis or osteopenia based on medical history and radiographic images
15. Current use of nicotine products.
16. Requires other surgical procedures at the time of the HTO surgery excluding arthroscopic exploration, chondroplasty, meniscectomy and cartilage preservation procedures
17. Diabetes mellitus

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Southmead Hospital
North Bristol NHS Trust Westbury-on-Trym
BS10 5NB
United Kingdom

Sponsor information


North Bristol NHS Trust

Sponsor details

Research and Innovation
Level 3
Learning and Research Building
Southmead Hospital
BS10 5NB
United Kingdom
+44 (0)117 4149336

Sponsor type

Hospital/treatment centre



Funder type


Funder name

Newclip Technics

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

National Institute for Health Research

Alternative name(s)


Funding Body Type

government organisation

Funding Body Subtype

National government


United Kingdom

Results and Publications

Publication and dissemination plan

Planned publication in a high-impact peer-reviewed journal.

IPD sharing statement:
The data sharing plans for the current study are unknown and will be made available at a later date.

Intention to publish date


Participant level data

To be made available at a later date

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

12/05/2020: Due to current public health guidance, recruitment for this study has been paused. 03/02/2020: Trial's existence confirmed by the National Institute for Health Research (NIHR).