There wasn’t a single defining case, but

rather a progressive shift in my clinical

practice. I became the primary referral

surgeon for paediatric patellofemoral

instability within my institution, managing

approximately 50 such cases per year.

With that volume, it became increasingly

important to optimise outcomes in a group

of patients who present unique anatomical

and developmental considerations.

Attending specialist meetings, including

paediatric knee conferences such as the Kid

Knee meeting in Sheffield, further

highlighted the need to refine our approach.

This led me to focus on developing a

technique that addresses instability in an

anatomical and reproducible way, while

respecting the distal femoral physis and

avoiding unnecessary donor site morbidity

by preserving the hamstrings.

The main challenge lies in the variability of

skeletal maturity in this age group.

Chronological age does not always reflect

skeletal maturity, and surgeons must carefully

assess the relationship between the planned

femoral fixation point and the distal femoral

physis. Another important consideration is

balancing stability with the risk of over-

constraint. Adolescents may still undergo some

degree of growth, so reconstruction must

restore stability without excessively tightening

the medial restraint of the patellofemoral joint.

This becomes particularly relevant when using

synthetic ligaments. At this stage of

development, growth is predominantly

longitudinal rather than radial, and overall knee

dimensions are approaching adult morphology.

As a result, the risk of progressive over-

tensioning of a non-elastic synthetic MPFL

construct is likely reduced compared to

younger children.

Fluoroscopy plays a critical role in safely

identifying the femoral insertion point

while protecting the distal femoral physis.

Research has highlighted that Schöttle’s

point is consistently located distal to the

medial femoral physis, which aligns with

my clinical experience.

Intraoperatively, I begin by obtaining a

true lateral radiograph to identify

Schöttle’s point. On this view, the entry

point may appear to overlap or even

traverse the physis. However, this can be

misleading due to the characteristic “W-

shaped” morphology of the distal femoral

physis. The medial limb of this “W” slopes

proximally, creating the illusion that the

entry point lies within the physis on the

lateral projection.

For this reason, I always confirm

positioning with an AP view before

entering the bone. The AP radiograph

reliably demonstrates that Schöttle’s

point is distal to the physis on the medial

side. Once confirmed, the Beath pin is

placed onto the periosteum and gently

tapped into the epiphysis rather than

drilled, minimising the risk of thermal

injury.

The guidewire is directed slightly

anteriorly and distally, ensuring that the

femoral socket remains entirely within

the epiphysis and away from the physis. A

hand reaming technique is then used to

create the socket, further reducing the

risk of thermal damage.

Although some adult techniques rely on

anatomical landmarks without

fluoroscopy, I would strongly advocate

routine use of image intensification in

paediatric cases, where direct

visualisation of the physis is essential to

ensure safe and accurate tunnel

placement.

In adolescent patients, avoiding donor-site

morbidity is an important consideration.

Harvesting hamstring tendons can lead to

measurable strength deficits, and in younger

patients the gracilis tendon is often relatively

small, occasionally necessitating harvest of the

semitendinosus to achieve an adequate graft.

Preserving these structures is particularly

valuable in active patients.

In addition, many patients presenting with

patellofemoral instability in this age group

demonstrate features of generalized

ligamentous laxity. In such cases, autograft

tissue may itself be relatively compliant, raising

the possibility of graft elongation over time. A

synthetic ligament offers a more consistent

construct, which may be advantageous in this

cohort.

There is also emerging clinical evidence

supporting the use of synthetic ligaments in

MPFL reconstruction. Work by Hersh Deo using

the XIROS 5mm Infinity Lock tape has

demonstrated excellent clinical outcomes with

low failure rates, providing a strong foundation

for further application in selected patients.

From a technical perspective, the XIROS Infinity

Loop tape has a low-profile, flat configuration,

which is well suited to the relatively superficial

anatomy of the MPFL, particularly in paediatric

patients. Its open-weave structure also allows

for tissue ingrowth and biological integration

over time.

In my early experience, patients have

demonstrated a rapid recovery and high levels

of satisfaction. While there is a theoretical risk of

over-constraint with non-elastic constructs,

careful patient selection and appropriate

intraoperative tensioning are key. We are

currently undertaking structured follow-up of

our paediatric cohort and hope to report these

outcomes in due course.

One of the key differences in this

technique is that it reverses the traditional

sequence of fixation. Rather than fixing on

the patella first and tensioning on the

femoral side, I perform femoral fixation

initially using a blind-ending socket within

the distal femoral epiphysis, and then

tension the construct on the patellar side.

This approach allows much more

controlled assessment of patellar tracking.

By passing the synthetic tape through

two transverse patellar tunnels and

temporarily securing it on the lateral side

with a clamp, I can assess patellar stability

dynamically through a full range of

motion. This includes full extension, 30

degrees, and 60 degrees of flexion, while

also evaluating lateral translation. It allows

both hands to be free, facilitating a more

accurate and reproducible assessment of

appropriate tensioning.

On the patellar side, careful preparation is

essential to minimise the risk of fracture.

The use of small-diameter (2.4 mm)

transverse tunnels creates a minimal bony

footprint and reduces stress risers. Once

appropriate tension is confirmed, final

fixation is performed on the medial side

using PEEK bone anchors, typically 3.5

mm or 4.75 mm depending on patellar

size, which can be planned preoperatively

using imaging. Importantly, only the

medial portion of the patella requires

preparation for anchor placement, rather

than full-length drilling across the entire

patella, further reducing risk.

Additional technical considerations

include the use of a tap in patients with

denser bone to facilitate anchor insertion

and minimise stress on the patella. Early

in the learning curve, an ACL guide can

assist with accurate tunnel placement,

although this becomes less necessary

with experience. Overall, careful attention to tunnel size,

controlled tensioning, and dynamic

assessment of patellar tracking are key to

achieving a stable reconstruction while

avoiding complications such as patellar

fracture or over-constraint.

The graft is typically fixed with the knee in

approximately 30 degrees of flexion. At this

position, the patella is beginning to engage the trochlea, allowing a reliable assessment of medial restraint. In this technique, I tension the graft on the

patellar side rather than the femoral side. By

temporarily securing the synthetic tape on the lateral side of the patella with a clamp, I am able to assess patellar tracking dynamically using both hands. This allows evaluation of lateral translation and tracking through a range of motion,

including full extension, 30 degrees, and 60

degrees of flexion. In my experience, this provides a more controlled and reproducible method of assessing tension compared to femoral-side tensioning, where

manual control can be more limited.

It is important that the graft functions as a check- rein rather than a rigid restraint. In particular,

when using a synthetic ligament in this age

group, it is preferable to err slightly on the side of a looser construct rather than risking over-constraint. Excessive tension should be avoided to minimise the risk of medial patellofemoral overload and altered joint mechanics.

In our early experience, patients have

demonstrated excellent restoration of

patellar stability following synthetic MPFL

reconstruction. Recovery has been relatively

rapid, which we attribute in part to avoiding

hamstring harvest and therefore reducing

overall surgical morbidity.

Patients have reported high levels of

satisfaction and have been able to return to

their previous activities, and in some cases

exceed their pre-injury level of function.

Importantly, we have not observed any

cases of over-constraint with the synthetic

construct when appropriate tensioning

principles are followed. Radiographic

follow-up with long-leg alignment films has

not demonstrated any change in coronal

alignment, and we have not identified any

evidence of physeal injury when femoral

fixation is performed using a careful,

fluoroscopy-guided technique.

We have also performed postoperative MRI

assessments in our cohort, which have not

demonstrated any evidence of patellar tilt

or medial over-constraint. These imaging

findings provide further reassurance that

the reconstruction restores stability without

adversely affecting patellofemoral

mechanics.

Our early cohort has now been followed for

at least one year, and complication rates to

date have been very low. We are continuing

structured follow-up, including comparison

of pre- and postoperative MRI findings, to

better understand how the synthetic

ligament contributes to stability over time

and how it behaves in relation to femoral

growth as patients continue to develop. We

hope to present and publish these results

to further inform clinical practice.

There is an increasing recognition that

patellofemoral instability is multifactorial, and not solely the result of MPFL insufficiency. Factors such as trochlear morphology, coronal and rotational alignment, and generalized

ligamentous laxity all play an important role, and need to be considered when planning treatment. As a result, the future of MPFL reconstruction in paediatric and adolescent patients is likely to

move toward a more individualised, anatomy-driven approach, where reconstruction is combined with correction of underlying risk factors when necessary.

In addition, there is growing interest in

alternative medial stabilising structures such as the medial quadriceps tendon–femoral ligament (MQTFL), which attaches from the distal quadriceps tendon to the femur near Schöttle’s point. This may offer another option for restoring medial restraint, particularly in patients where

patellar fixation is less desirable.

We are also likely to see increasing comparative data on different graft choices, including hamstring autograft, quadriceps-based techniques, and synthetic ligaments. As this evidence evolves, it will allow for more tailored, patient-specific surgical decision-making. Over the next five to ten years, we can expect more robust long-term outcome data to emerge, not only for isolated MPFL reconstruction but also for combined procedures addressing these

contributing factors. This will allow us to better understand which patients benefit from additional interventions and how best to optimise long-term joint health.

From a clinical perspective, we are already seeing the long-term consequences of untreated instability, with patients presenting later in life with patellofemoral degeneration requiring joint replacement. Earlier and more comprehensive management of instability may help to preserve joint function and delay or prevent this progression. Synthetic reconstruction is likely to play an increasing role in selected patients, particularly where preservation of native tissues is desirable. As further outcome data becomes available, its role will become more clearly defined within the broader management strategy for

patellofemoral instability.