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Proximal femoral endoprosthesis- Adler Pantheon for reconstruction after radical excision of femoral metastasis and trochanteric reattachment using Kinamed SuperCables

    Overview

    Professional Guidelines Included
    Learn the Proximal femoral endoprosthesis: Adler Pantheon for reconstruction after radical excision of femoral metastasis and trochanteric reattachment using Kinamed SuperCables surgical technique with step by step instructions on OrthOracle. Our e-learning platform contains high resolution images and a certified CME of the Proximal femoral endoprosthesis: Adler Pantheon for reconstruction after radical excision of femoral metastasis and trochanteric reattachment using Kinamed SuperCables surgical procedure.
    Metastatic bone disease is becoming increasingly prevalent and more cases are presenting to orthopaedic surgeons. These patients may be referred by GPs or from emergency departments or oncologists with skeletal related events, such as severe pain, impending fracture or pathological fracture, metastatic spinal cord compression or hypercalcaemia.
    Metastatic prostate cancer is the second most common presentation of metastatic bone disease to orthopaedic oncologists, after breast cancer. Prostate cancer frequently metastasises to bone and surgical options may include stabilisation of pathological fractures, arthroplasty, spinal decompression, resection and endoprosthetic reconstruction. Almost half the patients with prostate cancer who develop bone metastases develop skeletal related events within nine months of the development of skeletal disease.
    In this case, a patient with carcinoma of the prostate was referred by their oncologist, having undergone whole-body staging for an increasing PSA using a Choline PET-CT, which identified an asymptomatic proximal femoral metastasis. After discussions between the patient, oncologist and surgeon, it was decided that there was an advantage to the patient of excision of this solitary prostate bone metastasis (oligometastasis = <3 metastatic lesions) for local control and improved oncological outcomes. The underlying principle regarding the term ‘oligometastatic’, coined in the 1990s, is that treatment still has curative intent, which sadly is rarely the case in patients with multiple metastases.
    The patient underwent excision and reconstruction with a modular Adler Pantheon proximal femoral endoprosthesis with reattachment of the greater trochanter, to permit early weight-bearing and rapid return to function. The Adler Pantheon system was selected for this case because of the 3D printed bridging collar designed to achieve bone in- and on-growth to minimise the risk of aseptic loosening and trochanteric reattachment failure, the Agluna silver coating to minimise the risk of early prosthetic joint infection, and modularity to permit any possible segmental reconstruction of the proximal femur.

    Indications

    INDICATIONS
    The indications for a proximal femoral endoprosthesis are to reconstruct segmental bone loss following excision of the proximal femur for bone tumours, failed trauma osteosynthesis or failed arthroplasty. Where the trochanter is not involved by the tumour and can be spared, it is thought to be advantageous to osteotomise the trochanter to preserve the attachments of the gluteus medius and the vastus lateralis, both to maintain function of these muscles and also to improve soft-tissue coverage of the prosthesis to minimise the risk of infection.
    SYMPTOMS & EXAMINATION
    Patients with proximal femoral metastasises usually present with pain, causing inability to bear weight, necessitating walking-aids. Patients with tumours with extra-osseous spread outside of the bone may have soft-tissue swelling apparent in the proximal thigh. Very large tumours may start to cause obstruction of venous return, causing generalised swelling of the whole limb and may start to involve neural structures such as the sciatic nerve causing neurological sequalae in very rare cases.
    In this particular case, the patient was asymptomatic, as this tumour was detected both biochemically (PSA) and with whole-body imaging (PET-CT). Should the patient develop a pathological fracture, patients classically present with prodromal pain prior to a low energy fracture, out of keeping with the normal injury mechanism for a hip or femoral fracture.
    IMAGING
    All patients with suspected metastatic bone diseases, should have x-rays of the whole bone, so in this case an x-ray of the whole femur AP and lateral and MRI scan of the whole bone and if it involves the hip joint, to include the pelvis as well and they should have a staging CT chest, abdomen & pelvis. In this case, the patient already had a whole-body Choline PET-CT for distal staging, which confirmed that this was a solitary bone metastasis.
    Other alternatives for distal skeletal staging, would include whole body bone scintigraphy or whole-body MRI. In addition, sometimes a CT scan is useful of the bony metastasis to assess for skeletal integrity or if one is planning a custom endoprosthesis.
    If, a patient presents with a solitary metastasis a biopsy is usually indicated, as per the BOA (British Orthopaedic Association) guidelines 2015 (which are available in the guidelines section) to confirm the diagnosis and exclude the rare possibility of a primary bone tumour or of a different diagnosis. It is not uncommon for patients to have more than one diagnosis and in a recent investigation of our local data, it was found that in patients with a previous history of malignancy and a solitary bone lesion, 20% had a different diagnosis to their previous cancer.
    Bone biopsy can be performed in theatre using a Jamshidi needle and image intensification or done using CT guidance by the radiology team.
    Once the diagnosis is confirmed, then the patient’s case is normally discussed at a disease specific MDT, in this case the urology MDT and a discussion is had with the patient’s treating oncologist, who in this case referred the patient, prior to undergoing excision and reconstruction of the oligometastatic bone disease.
    ALTERNATIVE OPERATIVE TREATMENT
    Alternatives to surgical en-bloc resection and reconstruction may include intra-medullary nail stabilisation in a patient for palliative management of an impending or pathological fracture with polyostotic disease. In oligo-metastatic disease this would not excise the tumour, merely stabilise the bone. In non-oligometastatic disease, i.e. where the treatment intent is palliative, then cephalo-medullary nails would be reasonable but are associated with a high revision rate due to mechanical failure and disease progression.
    NON-OPERATIVE MANAGEMENT
    Non-operative management in general for metastatic bone disease, may include radiotherapy, hormone therapy, chemotherapy, immunotherapy and minimally invasive techniques may include cryotherapy or cementoplasty for pelvic disease.
    In this case a Cyberknife, which is a form of targeted radiotherapy, was discussed but felt inappropriate because it is a weight-bearing bone, but this may be considered in other anatomical areas.
    CONTRAINDICATIONS
    Contraindications to surgery, include those patients whose prognosis is thought to be less than six months, in which case palliative radiotherapy maybe more appropriate, or in patients with multiple morbidities preventing anaesthesia and major surgery. Indications might include active infection or concurrent pulmonary embolus.

    Setup

    The patient is positioned right side down and left side up and appropriate anaesthetic (in this case combined spinal anaesthesia with general anaesthetic) with pressure aero protection and routine hip props with intravenous antibiotic prophylaxis administered one hour prior to skin incision (flucloxacillin and gentamicin as per local antimicrobial guidelines) and the urinary catheter and intravenous tranexamic acid.
    The patient has isolation drapes and pre-operative skin cleansing, using alcoholic chlorhexidine twice with suction and electrocautery available.

    Operation – 1

    Shows a whole body Choline PET-CT, showing significant uptake in the liver and the bowel and bladder as one would expect but also uptake in the left proximal femoral metaphysis suspicious for a solitary bone metastasis, given this patient’s background history of prostate cancer, for which he had been treated with hormone therapy for many years, which had previously kept his PSA (prostate-specific antigen) normal.

    T2-weighted coronal MRI sequence showing abnormality in the proximal femoral metadiaphysis concerning for a prostate metastasis.

    Axial CT slice showing a biopsy a needle being inserted laterally into the left proximal femoral meta-diaphysis at the time of the biopsy to confirm the diagnosis of metastatic prostate cancer.

    X-ray of the proximal femur and hip joint showing surgical clips in the pelvis from the previous radical prostatectomy five years earlier and a area of localised sclerosis in the proximal meta-diaphysis distal to the lesser trochanter at the site of the abnormality on the MRI scan and the Choline PET.

    Coronal CT whole left femur, again showing focal endosteal sclerosis consistent with metastatic prostate carcinoma but showing no cortical erosion or loss. It also shows there is no disease in the greater trochanter which can be osteotomised for soft tissue reconstruction at the end of the operation. There is no further disease elsewhere in the distal femur.

    Post-operative x-ray.
    AP pelvis showing satisfactory and location of the prosthesis and reattachment of the osteotomised trochanter onto the prosthesis.

    Post-operative x-ray of the femur showing satisfactory cementation and fit the endosteal collar at the bone prosthesis interface and reattachment of the trochanteric osteotomy. The collar is sat proud of the bone hence the lucent line between the collar and bone, which to date has no caused a problem but frequently encountered.

    The whole left lower-limb is isolated using surgical drapes and the skin has had an initial cleanse with alcoholic chlorhexidine skin preparation.
    The intended surgical incision is marked with marker pen, centred over the greater trochanter, curved slightly over the buttock for a routine posterior approach to the hip and this is an extensile approach proximally and distally which can be extended down the thigh to the knee and proximally into a Kocher-Langenbeck pelvic approach.

    Immediately prior to skin incision. Following a further skin cleanse with chlorhexidine, the lower leg has been covered with surgical drapes and the skin covered with Ioban incisional drapes, the intended skin incision is still seen through the drapes.

    The skin incision is made along the skin mark centred over the greater trochanter, deepened through the dermis and fat, down to the deep fascia.

    Using cautery, the skin incision is deepened through the fat and any bleeding vessels are cauterised as we proceed through the fat layer.

    The deep fascia has been identified and punctured using the cautery and an artery clip is slipped under it.The fascia lata is elevated off the deeper structures, to avoid inadvertent cautery onto the tumour and to help divide the fascia lata in line with the fibres of the gluteus maximus beneath.

    Identify the sciatic nerve.Having divided the fascia lata and split the fibres of the (GM) gluteus maximus, which are visible at the top of the wound, the (GT) greater trochanter and the (VL) vests lateralis are visible. Posterior to the greater trochanter, the (ERs) external rotators can be seen and by gentle palpation between the gluteus maximus and the external rotators, the (Sn) sciatic nerve which is pointed out can be felt and/or seen, this is an important and vital structure to preserve and protect throughout the operation.

    Release the gluteus maximus tendon off the posterior femur then release quadratus femorisHaving identified the (Sn) sciatic nerve, insert an artery clip beneath the (GMax) gluteus maximus tendon and using cautery, divide the gluteus maximus tendon about 1 cm away from its insertion onto the femur. Care is taken not to inadvertently damage the first perforator vessel which courses around the femur at this level and the sciatic nerve which is deep to the gluteus maximus tendon.

    Having released the gluteus maximus tendon off the posterior femur, again using an artery clip placed underneath, release the quadratus femoris muscle, which is the next structure proximally after the gluteus maximus tendon, to begin the approach to excising the proximal femur. Again, the sciatic nerve is clearly visible and at risk during this step.

    Identify the piriformis and obturator internus tendonsPlace a Hohmann retractor beneath the (GMed) gluteus medius and minimus onto the hip joint capsule, overlying the femoral head and by elevating the retractor the (P) piriformis tendon is clearly visible inserting into the piriformis fossa at the tip of the (GT) greater trochanter. From proximal to distal the structures released are piriformis, superior gemellus, (OI) obturator internus, inferior gemellus, obturator externus, and (QF) quadratus femoris with the joint capsule beneath. Allow the rotators to reflect over the sciatic nerve for protection during the procedure. The (VL) vastus lateralis is shown to the right of the photo arising from the flare of the trochanter.

    Perform a capsulotomy of the hip.Divide the external rotators and hip capsule from proximal to distal as shown using cautery. Be aware of the little vessels which require coagulation using the diathermy during this step.

    The (FH) femoral head and neck are now visible through the capsulotomy and the tendons and muscles at the back of the femur have all been released to the pertrochanteric region.

    place stay sutures into the external rotators.Using No. 1 vicryl stay sutures, are placed into the (P) piriformis and obturator internus tendons as shown for re-attachment later and is useful for judging offset at the time of trialling, like a routine hip replacement. This helps to keep the external rotator layer together and to lie over the sciatic nerve for protection during the operation.

    Elevate then release the vastus lateralis off the femurInset a Hohmann’s retractor beneath the deep fascia of the (VL) vastus lateralis from posterior to anterior and use this to retract the vastus lateralis anteriorly, almost exposing the (F) femoral shaft as shown. I insert the Hohmann’s beneath the vastus lateralis muscle, at the level of the divided gluteus maximus tendon. This still leaves a layer of muscle and periosteum on the bone tumour for a resection margin.

    Using cautery, divide any tissue retaining the (VL) vastus lateralis up to the vastus ridge, which is the origin of the vastus lateralis muscle, just distal to the bare area of the (GT) greater trochanter.

    Measure the position for osteotomy of the trochanter and proceedUsing a metal ruler and Kocher’s forceps to identify the tip of the (GT) greater trochanter, measure the length of the pre-planned trochanteric osteotomy based on the MRI and CT scan. The intended line of the osteotomy has been marked using cautery around the back of the trochanter, from a line starting at the vastus ridge, were the (VL) vastus lateralis is originating to the greater trochanter in the piriformis fossa, to include the (GMed) gluteus medius tendon insertion.

    Using an oscillating saw with a 1.27 mm blade begin the osteotomy from posterior to anterior. Care is taken to judge the angle, so that the bone is osteotomised to preserve the (GMed) gluteus medius insertion onto the trochanter anteriorly, superiorly and posteriorly. I tend to ensure that the knee and foot are level with the floor so that i can appreciate the rotation of the femur.

    Continue the osteotomy until feedback from the oscillating blade confirms that the anterior cortex has been cut.

    Complete the trochanteric osteotomy using an osteotome and mobilise the trochanteric osteotomyRemove the saw blade and take a broad osteotome and insert it into the osteotomy to complete the osteotomy anteriorly, proximally and distally and then use the osteotome to elevate the (GT) greater trochanter (as shown) whilst simultaneously externally rotating the femur. This as can been seen this preserves the (GMed) gluteus medius tendon insertion onto the trochanter in continuity with the (VL) vastus lateralis origin distally.

    Operation – 2

    Using Hohmann’s retractor and a Langenbeck’s retractor, the trochanteric osteotomy is retracted anteriorly, and cautery is used just to free up any capsular attachments to the osteotomised fragment, to mobilise the trochanteric osteotomy.

    Continue dissection distally towards the femoral resection point. Using cautery elevate the remaining vastus lateralis off the femoral shaft distally, leaving a small cuff of tissue on the bone as a resection margin; there are no vessels or nerves in this area to be concerned about, merely intra-muscular branches.

    Release vastus intermedius off femur then measure the femoral resection point Now release the (VI) vastus intermedius off the anterior aspects of the proximal (F) femur and this is aided by the use of artery clip placed under the muscle to elevate it off the bone and maintain tension when using the cautery.

    Continue to release the soft-tissues off the proximal femur, all the way up to the hip joint anteriorly, again preserving a small margin of small rim of muscle on the bone as a surgical resection margin, to ensure a complete resection of the tumour.

    Using a metal ruler and Kocher’s forceps, measure of the tip of the (GT) greater trochanter down to the level of femoral resection, as per pre-operative planning using the T1 weighted MRI scan. We can see that the posterior and anterior femur have been skeletonised leaving only the medial adductor structures to be released off the femur following the femoral osteotomy.

    Release sort head of biceps femoris off linea asperaThe femur is now put in a maximal internal rotation, revealing the (LT) lesser trochanter and the (FN) femoral neck more clearly. The short-head of biceps femoris is released off the femur, again leaving a cuff of muscle as a surgical margin. The short head of biceps femoris arises from the lateral portion of the linea aspera and conjoins with the long head (arising from ischial tuberosity). Of note the short head is innervated by the common fibular branch of the sciatic nerve whereas the long head is innervated by the tibial branch (this difference is useful for EMG assessments if one is investigating a suspected foot drop).

    Remeasure the femoral osteotomy. Double check the measurement before the osteotomy and mark the level of the osteotomy using cautery and an osteotome perpendicular to the anatomical axis of the femoral diaphysis.

    A 1.27 mm oscillating saw blade is used to divide the femoral shaft at the level of the resection point from the pre-operative planning.Use a Langenbeck and two Hohmann’s retractors around the femur to protect the soft tissues.

    Following the femoral osteotomy, a Heygroves bone holding forceps is placed onto the proximal side of the osteotomy to elevate the femur out of the wound using the hip joint as a fulcrum.
    This permits access to the medial abductor muscles, which can be divided off the femur using cautery.
    Care is taken not to damage the profunda femoris vessels which lie medial to the femur between the vastii and adductor brevis and pectineus.

    The last structure to be divided is the psoas tendon at the level of the (LT) lesser trochanter. A clip is placed behind the psoas tendon to help divide it using cautery close to the lesser trochanter and this enables the femur to be lifted out of the wound and the (FH) femoral head dislocated.

    Dislocate the femoral headFollowing dislocation of the femoral head, the final structure to be cut is the ligament teres (not visualised because it is within the acetabulum) using cautery or curved scissors.

    Measure the femoral head using callipers in two places to determine diameter for the hemiarthroplasty reconstruction.

    Measure the femoral head then trial the hemiarthroplasty headTrial the hemiarthroplasty head, taking the appropriately sized unipolar head trial off the Adler Pantheon set, place this into the acetabulum and assess for whether the size is correct. There should be a suction effect and it should be difficult to remove without breaking the suction seal using an instrument (suggesting undersized) and it shouldn’t be oversized such that the head doesn’t reach the floor of the acetabulum and there is resistance to rotation.

    Prepare the femur by sequential reamingUsing Heygroves bone holding forceps to grasp the residual distal femur, use the sequential femoral reamers off the Adler Pantheon set to prepare the medullary canal.
    These reamers start at 8 mm and increase in 1 mm intervals. These are inserted anterograde and increase in size until cortical chatter indicating endosteal fit has been reached.
    The reamer should be inserted until the (LM) laser mark on the reamer is level with the femoral osteotomy.

    The Adler Pantheon system is designed to use the femoral reamer as a spigot for endosteal reaming and face reaming, so once the desired reamer size has been reached, confirmed when axial and rotational stability has been achieved, uncouple and leave the reamer in-situ inside the femur.

    Leaving the spigot of the femoral canal reamer in-situ in the distal femur, take the appropriately sized face reamer for the diameter of the femoral reamer and place it over the spigot. the bridging collar of the prosthesis comes in three sizes (small, medium and large), so whichever matches the disputer of the femur closest is selected.

    Using the powered face reamer, plane the femoral osteotomy to optimise contact between the 3D-printed bridging collar and the residual distal femur for maximal bony on-growth and in-growth, to prevent aseptic loosening.

    Sequentially ream the endosteal bone using the endosteal reamer (shown) which is also placed over the spigot. Each stem size has a corresponding endosteal reamer size, so if the femoral reamer in-situ is 11mm then ream up to the matching 11mm endosteal reamer. This is because each bridging collar corresponds to the intended stem that is to be implanted.
    Ensure the endosteal reamer is flush with the osteotomy to allow accurate seating of the definitive collar, to maximise bone in and on growth onto the collar

    Having reamed the endosteum, a channel can be seen between the femoral reamer and the endosteum, where the femoral collar will sit for endosteal bone in- and on-growth to the collar to minimise the risk of aseptic loosening.

    On the back table, assemble appropriate parts to form a modular trial prosthesis.
    Using the trial head with a trochanter and a shaft and a collar, which click together to make a trial.
    The shafts range from 35 mms to 140 mms and increase in 15 mm increments. The trochanters come in two lengths (50 & 70mm) and three offsets, small, medium and large with and without flat trochanteric reattachments.
    The collars range from 26 – 34 mms in small medium and large sizes. When shown next to the resected femur, it can be seen at the reconstruction approximates the length of the resection.

    The trial endoprosthesis can be inserted over the spigot of the femoral reamer, so that this doesn’t need to be removed for trialling, as the collar and shaft are cannulated to accept the spigot.

    Construct the modular trial and insert in femur and reduce the modular trial prosthesisOnce the trial prosthesis is located over the reamer’s spigot, reduce the head into the acetabulum and assess for limb length, offset and stability, as one would for a hip replacement or an endoprosthetic replacement. To reduce the trial, the assistant applies gentle longitudinal traction and the surgeon pushes the trochanter of the prosthesis into joint as shown.

    Alternatively, the prosthesis comes with trial stems which can be added to the bottom of the shaft as shown next to the receptive proximal femoral on the back table.
    Cemented stems are 115mm long and range from 11 to 16mm, alternatively cement less stems range from 11 to 24mm in diameter.

    Insert a cement restrictor 125 mm distal to the femoral osteotomy, to allow space for the 115mm femoral stem.

    Wash the canal and woundUsing pulsed-lavage, irrigate the wound bed and the femoral canal to remove clot to improve cement interdigitation and help to prevent infection.

    Operation – 3

    Dry the femoral canal using ribbon gauzePack the femoral canal above the cement restrictor to dry the endosteum prior to cementation. This helps to improve cementation. Optimal cement technique affords optimal primary stability of the cemented endoprosthesis.

    Construct the definitive modular prosthesisAll the parts required to assemble the Adler Pantheon modular proximal femoral endoprosthesis are shown.
    These include the (Tw) torqued wrench and it’s adaptor, the (FI) femoral impactor and the (HI) head impactor, the (Ts) trochanteric screw, the definitive (T) trochanter of the prosthesis, the definitive (S) shaft of the prosthesis, both of which are silver coated, and the 3D printed (Bc) bridging collar, the 28 mm (FH) femoral head and the 54 mm (BH) bipolar head, 115 mm (Cs) cemented stem and the assembly (BP) base plate.

    Slide the (Bc) bridging collar over the (Cs) cemented stem so that the trunnion engages; this can only go on one way.

    Impact collar on stem with tubeTurn the bridging collar and stem upside down and insert onto the impaction base plate and using the (FI) femoral impactor, gently tap to engage the trunnion of the bridging collar on the cemented stem.

    Add the shaft to the stemNow add the silver coated (S) shaft to the (Bc) bridging collar and (Cs) cemented stem, which is also upturned and placed onto the impactor base plate in the same way.

    Impact cemented stem onto shaft with impactorThe previous step is repeated: using the (FI) femoral impactor, hit the (S) shaft onto the cemented stem with gentle taps to engage the morse taper.

    Impact trochanter onto shaft with impactorNow add the (T) trochanteric portion of the prosthesis to the (S) shaft and again upturn this and there is a nipple to rest the shoulder of the trochanter of the prosthesis onto for impaction of the trunnion, by hitting the tip of the stem.

    Insert the (Ts) trochanteric screw, the screw is inserted into the hole at the top of the (T) trochanter, this helps to engage the morse taper between the shaft and the trochanter, this can also be removed in-vivo and a longer screw inserted to break the taper, should you wish to disengage the components or change the rotation of the trochanter on the shaft. This might be necessary if there was concern after cementation about the anteversion of the prosthesis, which is element to hip stability.

    Screw the locking bolt into shoulder of the prosthesisTorque the trochanteric screw, using the (AT) anti-torque device placed over the femoral neck and the (TW) torqued-wrench. The screw is torqued to engage the morse taper between the shaft and trochanter. There is a laser mark on the torqued-wrench to show you how far to tighten the screw.

    Using a clip supplied on the Adler Pantheon set, insert the clip into the two holes on the polyethene collar of the (BH) bipolar head to remove the retaining collar from the bipolar head. If you do not remove this collar the bipolar head will not seat over the 28 mm femoral head.

    Add the 28mm femoral head to the definitive prosthesis, followed by the bipolar headAdd the 18mm (FH) femoral head to the trunnion of the femoral neck. Place the collar over the femoral neck. Using the clip, place the polyethene collar around the femoral neck before implanting the bipolar head.

    Place the (BH) bipolar head onto the 28 mm head and using the clip push the polyethene bipolar clip into place to stop disengagement of the bipolar head from the 28 mm femoral head.

    The definitive prosthesis is now assembled. The prosthesis is shown on the back table prior to cementation: the (BH) bipolar head, the (T) trochanter, (S) shaft, (Bc) bridging collar and (Cs) cemented stem.


    A size specific canal pressuriser is supplied with each cemented stem. This pressuriser allows for displacement of the femoral stem into the cement mantle, to prevent any cement reaching the junction between the bridging collar and the bone to maximise endosteal in- and on-growth.

    Retrograde fill of the femoral canal with cementHaving placed the cement tool into the femoral shaft, the cement nozzle is placed through the cementing tool and retrograde filling of the canal takes place until the pressure of the cement starts to push the cementing tool out of the shaft, at this point the canal filling ceases and the tool and the cement gun are removed from the femoral canal. This should leave just enough cement in the femoral canal to accommodate displacement of the cemented femoral stem.

    Insert the definitive prosthesis into the distal femur and impact the shoulder of the trochanter finally.As this step is being performed, be careful to recreate the anteversion that you require following trialling of the prosthesis. If after cementing the prosthesis the anteversion is incorrect then, the rotation of the trochanter can be changed later, but would be an additional step in the procedure. Alternatively the cemented stem and bridging collar can be cemented into place and the shaft and trochanter added afterwards.

    Having inserted the femoral stem inside the canal, the definitive prosthesis is shown immediately prior to reduction of the head into the acetabulum.
    I prefer to reduce the prosthesis into the joint whilst the cement is curing, to minimise any rotation during cement curing, which could affect the quality of the cementation.

    Having reduced the prosthesis into the hip joint, impact the shoulder of the trochanter to engage the prosthesis into the distal femur further, which should prevent any further rotation due to the primary stability the 3D printed bridging collar affords, even before the cement has cured.

    Purse string suture of hip capsule around bipolar headUsing 1.0 vicryl, a purse string suture is placed into the residual capsule around the femoral head to help improve stability and prevent dislocation of the prosthesis. A purse string suture is a running suture into the residual hip capsule tissue, which when tied, constricts the capsule around the bipolar head.

    Approximate the trochanteric osteotomy onto the shoulder of the prosthesisThe silver coated prosthesis has a 3D printed shoulder for osseointegration of the trochanteric osteotomy. Using Lanes soft-tissue holding forceps and grasping the vastus lateralis and the gluteus medius tendon, the osteotomy(1) is approximated onto this flat surface.

    Insert the supercablesUsing a artery clip to pierce the (GMed) gluteus medius anteriorly, two Kinamed SuperCables are pulled through the gluteus medius muscle anteriorly around the osteotomised trochanter. These polymer cables are thought to eliminate any metal debris caused by fretting. Keeping very close to bone to avoid inadvertent injury to the femoral vessels, pass the clip from posterior to anterior to create a passage for the SuperCables to pass.

    The SuperCables are then passed through the holes on the prosthesis as shown, so that when the SuperCables are tightened, the osteotomised trochanter is held onto the prosthesis.

    Apply the anti-bacterial hydrogel (Defensive antibacterial coating – DAC)A double mix of DAC (defensive anti-bacterial coating) are made on the back table, using a gram of powdered vancomycin with 20 mls of water for injection, this forms two 5 mls syringes of a hydrogel which is applied at this point to all of the metal on the prosthesis, to prevent biofilm formation and early prosthetic joint infection.

    The defensive hydrogel coating is now applied to all of the prosthesis as shown, including all the holes around the prosthesis.
    Animal models have shown that this does not retard osseointegration.

    Tighten the super cablesThe SuperCable tightener is used to tension the cables to the appropriate level to fix the trochanteric osteotomy to the prosthesis as shown. Pass the free ends through the tip of the tightener and then tension the cables using the screw mechanism whilst holding the cables close to the tightener as shown (to avoid them slipping from the tightening mechanism).
    This step is repeated for each cable. Once tensioned, the residual supercables are cut using a scalpel.

    Operation – 4

    The super cables have now been tightened. The trochanter has now been attached to the prosthesis which keeps the vastus lateralis and the gluteus medius in continuity and it covers the prosthesis almost entirely. Covering the prosthesis is important to minimise the risk of infection.

    Reattach the piriformis tendonThe (P) piriformis tendon is reattached to the (GMed) gluteus medius tendon using 1.0 vicryl sutures as shown.

    Repair the gluteus maximus tendonThe (GMax) gluteus maximus tendon is reattached to the (VL) vastus lateralis at the back of the femur using 1.0 vicryl as shown, this is important for soft-tissue coverage and stability and to reduce dead space. Be careful at this stage not to inadvertently damage the sciatic nerve, which runs underneath the gluteus maximus tendon.

    The gluteus maximus tendon has now been reattached to the vastus lateralis at the back of the femur, which dramatically improves the coverage of the endoprosthesis by soft-tissues.

    Reattach the external rotatorsThe external rotators are reattached to the back of the trochanteric osteotomy using interrupted vicryl sutures as shown, this completes the soft tissue coverage of the prosthesis.

    Close the fascia lata, then fat, then skin.Using an 0 looped PDS suture, the fascia lata is closed with a continuous suture to seal the deeper layer.

    After routine interrupted deep dermal sutures, a subcuticular monocryl and tissue glue are applied to the skin.

    An aquacel dressing is applied to the skin.

    Post Operative

    IV antibiotics for 24 hours (floxacillin), low molecular weight heparin, thromboprophylaxis for 28 days post-operatively and thromboembolic stockings for 6 weeks post-operatively plus foot pumps whilst in bed as an inpatient.
    No sutures to remove, wound check in 2 weeks.
    Protected weight bearing with crutches for 6 weeks from tomorrow, under physiotherapy supervision.
    Outpatient department, 6 weeks, repeat x-ray on arrival.
    Neurovascular observations on high dependency and overnight.
    Routine blood test next day and transfuse as appropriate.

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    Endoprosthetic reconstruction allows early weight bearing, shorter hospital stay, early return to daily living and commencement of post-operative adjuvant therapy. Aseptic loosening was the principle mode of failure of cemented lower-limb endoprosthetic replacements according to Unwin et al. (Unwin P, et al. Aseptic loosening in cemented custom-made prosthetic replacements for bone tumours of the lower limb. JBJS(Br) 1996, 78(1):5-13. PMID: 8898118). The other causes of failure are local recurrence, infection, dislocation and peri-prosthetic fracture. Aseptic loosening of the first generation of proximal femoral endoprostheses was reduced by the addition of hydroxyapatite (HA) collars at the bone-prosthesis interface in the 1990s. It was first reported in animal models that HA coated collars generated new bone that enhanced fixation and encouraged the osseo-integration, offering an alternative to the use of intramedullary cemented stems in patients with only a short segment of bone remaining (Stevenson JD, Wigley C, Burton H, Ghezelayagh S, Morris G, Evans S, Parry M, Jeys L. Minimising aseptic loosening in extreme bone resections: custom-made tumour endoprostheses with short medullary stems and extra-cortical plates. Bone Joint J. 2017 Dec;99-B(12):1689-1695. PMID: 29212694).
    Porous metal coatings have become routine in primary and revision hip arthroplasty. The addition of a 3D-printed porous collar to endoprosthetic replacement with endosteal integration may further reduce the incidence of aseptic loosening. Trials are underway within the UK to investigate this further at the Royal Orthopaedic Hospital, Birmingham and RNOH, Stanmore (https://clinicaltrials.gov/ct2/show/NCT03905174?term=MING&draw=2&rank=2).
    Endoprosthetic reconstruction allows early weight bearing, shorter hospital stay, early return to daily living and commencement of post-operative adjuvant therapy. Aseptic loosening was the principle mode of failure of cemented lower-limb endoprosthetic replacements according to Unwin et al. (Unwin P, et al. Aseptic loosening in cemented custom-made prosthetic replacements for bone tumours of the lower limb. JBJS(Br) 1996, 78(1):5-13. PMID: 8898118). The other causes of failure are local recurrence, infection, dislocation and peri-prosthetic fracture. Aseptic loosening of the first generation of proximal femoral endoprostheses was reduced by the addition of hydroxyapatite (HA) collars at the bone-prosthesis interface in the 1990s. It was first reported in animal models that HA coated collars generated new bone that enhanced fixation and encouraged the osseo-integration, offering an alternative to the use of intramedullary cemented stems in patients with only a short segment of bone remaining (Stevenson JD, Wigley C, Burton H, Ghezelayagh S, Morris G, Evans S, Parry M, Jeys L. Minimising aseptic loosening in extreme bone resections: custom-made tumour endoprostheses with short medullary stems and extra-cortical plates. Bone Joint J. 2017 Dec;99-B(12):1689-1695. PMID: 29212694).
    Porous metal coatings have become routine in primary and revision hip arthroplasty. The addition of a 3D-printed porous collar to endoprosthetic replacement with endosteal integration may further reduce the incidence of aseptic loosening. Trials are underway within the UK to investigate this further at the Royal Orthopaedic Hospital, Birmingham and RNOH, Stanmore (https://clinicaltrials.gov/ct2/show/NCT03905174?term=MING&draw=2&rank=2).

    Reference

    • orthoracle.com

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