Orthopaedic - The Transfemoral Approach in Total Hip Revision Arthoplasty

Prof. Heinz Wagner et Prof. Michael Wagner
Schwarzenbruck/Nürnberg, Germany
INTRODUCTION
Aseptic loosening in total hip replacement is associated with bone resorption. In advanced cases, the bone loss may be so severe that the firm fixation of a femoral prosthesis in the old implant bed will be difficult or even impossible. The Femoral Revision Prosthesis bypasses the defective femoral segment and is anchored in sound bone distal to the lesion. The revision prosthesis is designed for cementless fixation with a cone junction, impacting a conical stem into the conically reamed femoral canal. With a cone angle of 2(infinity), very little bone needs to be removed to obtain a conical seat for the prosthetic stem.
With a non-transfemoral approach, the removal of the loose femoral prosthesis, the bone cement and the granuloma is difficult and time- and blood-consuming, especially in the revision of long stems, and is fraught with the risk of uncontrolled fractures and perforations of the defective bone.
With the transfemoral approach, the femoral cavity is gently opened, facilitating the debridement and the preparation of the new implant seat distal to the bone defect. The acetabular component can be revised through the same approach. It is essential for subsequent bone healing to protect the overlying muscles and not to release them from the bone surface.
Preoperative planning is indispensable for the determination of the sizes of the prosthetic components and the extent of the transfemoral approach.
Surgical Technique

Fig. 1 : The transfemoral approach is carried out through a posterolateral incision, with the patient lying on his or her side.

Fig. 2 : Steps involved in the transfemoral approach: The approach consists of a transverse osteotomy at the distal end, a longitudinal osteotomy along the linea aspera, and a number of puncture osteotomies along the anterior border of what is going to be the lid.
A: A semicircular transverse osteotomy is made for the distal limitation of the transfemoral approach at the lower end of the defective segment of the femur. The location of this osteotomy is determined by the preoperative planning, and verified by measuring the distance from a defined reference point, normally the tip of the greater trochanter. (During the operation, the semicircular osteotomy can be extended to a complete transverse osteotomy, if this is required for the alignment of the antecurvatum or of a varus curvature of the femoral shaft).
B: A drill hole is made at the linea aspera for the posterior limitation of the transverse osteotomy; starting from this point, the longitudinal osteotomy along the linea aspera is carried out with fine flat chisels. Proximal to the tuberculum innominatum, the osteotomy is routed a little more anteriorly (A), in order to preserve a solid posterior piece of bone of the greater trochanter for later suturing.
C: An anterior drill hole is made for the anterior limitation of the transverse osteotomy; starting from this point, discontinuous puncture osteotomies in a proximal direction are made for the anterior limitation of the lid. For these puncture osteotomies, fine flat osteotomes are inserted between the muscle fibres without releasing the muscle from the bone.
D: At the linea aspera, the longitudinal osteotomy is carefully opened, and the lid is lifted with the muscles still in place. Then the prosthesis and the cement can be easily removed.

Fig. 3 : Posterolateral skin incision. Fig. 4 : After longitudinal incision of the fascia lata, the vastus lateralis muscle is exposed.

Fig 5 : A Steinmann pin is inserted at the tip of the greater trochanter (reference point). From this pin, the preplanned length of the transfemoral approach is measured in a distal direction; a second pin is inserted at that point. Fig. 6 : At the distal end of the transfemoral approach, a mark is made on the bone with a flat osteotome. Only at this point is the muscle released from the bone surface.

Fig. 7 : A drill hole is made at the posterior limit of the semicircular transverse osteotomy. Fig. 8 : Tha vastus lateralis muscle is carefully released from the lateral intermuscular septum. In a proximal direction from the drill hole, the longitudinal osteotomy is made along the linea aspera with sharp flat osteotomes, without violating the muscle. The osteotomy is routed toward the tip of the greater trochanter, where the proximal Steinmann pin is still in place.

Fig. 9 : After having made a drill hole at the anterior limitation of the transverse osteotomy, flat osteotomes are inserted between the muscle fibres, and discontinuous puncture osteotomies are made from the anterior drill hole in a proximal direction for the anterior border of the lid. The distance between the two drill holes determines the width of the lid. Fig. 10 : The posterior longitudinal osteotomy is carefully opened with chisels and fragment spreaders, and the cement mantle of the femoral prosthesis is exposed over its entire length.

Fig. 11 : After resection of the scar tissue around the neck of the prosthesis, the implant can be easily removed. Fig. 12 : With further displacement of the two pieces of the greater trochanter, spike retractors can be placed around the acetabular rim exposing the acetabular component over its entire circumference.

Fig. 13 : After removal of the polyethylene insert, the PMMA cement is cut into pieces to facilitate its removal and to prevent damage to the bony acetabulum. Fig. 14 : After careful debridement of the acetabular cavity and application of bone grafts to the defects, an uncemented acetabular component is inserted and firmly fixed.

Fig. 15 : Distal to the transverse osteotomy of the transfemoral approach, the medullary cavity is reamed with conical reamers to create a conical seat for the conical stem of the revision prosthesis. Due to the cone angle of 2(infinity), only very little bone needs to be removed. The depth of insertion of the reamer is measured and compared with the preoperative planning. Reaming must be continued until a strong frictional resistance is encountered and the depth of insertion of the reamer corresponds to the planned value. If, in soft bone, the reamer penetrates further, a thicker stem diameter must be used. Therefore, the final choice of the implant diameter should not be made before reaming is completed; also, the sterile prosthesis should not be unpacked before that stage.
When the reamer is retracted from the medullary cavity, fine bone shavings sticking to the sharp edges will indicate the extent of the conical cavity.
Distally to the transverse osteotomy, a double cerclage with 1.5 mm diameter stainless steel wire may be applied if necessary. Fig. 16 : The bone shell of the old implant bed is carefully curetted immediately prior to the insertion of the implant. This is not done any earlier, in order to minimize bleeding.

Fig. 17 : The femoral revision prosthesis is pushed into the medullary cavity with the impactor/retractor. Firm resistance will be encountered ca. 10-15 mm before the final position has been reached. Fig. 18 : A slotted hammer is placed on the shaft of the impactor/retractor, and the rotational position is checked with the limb at 90(infinity). In a left hip (example in this figure) counter-clockwise rotation increases the angle of anteversion, in a right hip vice versa.

Fig. 19 : A goniometer may also be used if desired. Then the prosthesis is impacted with only moderate tapping, just to give enough stability for a trial reduction. Firm impaction should be avoided at this point, so that the prosthesis can be easily mobilized if rotational correction becomes necessary. A short trial head is placed on the neck of the prosthesis, because the implant is not completely impacted and therefore "relatively too long". After reduction, the stability of the prosthetic joint is checked in flexion and internal rotation. Additionally, 10 kg longitudinal traction is applied to the straight leg: If the joint opens more than 8 mm, a longer modular head must be used.
If a rotational correction becomes necessary, which may depend also on the position of the acetabular component, the prosthesis is redislocated and mobilized with the impactor/retractor and the slotted hammer, and the rotational correction is carried out. Another trial reduction must then be performed.
For the final firm impaction of the revision prosthesis, regular tapping is applied to the impacting instrument. With every tap, the prosthesis will move a few millimeters distally, which can be seen clearly at the edge of the transverse osteotomy. Tapping is continued until the migration of the implant stops and continued tapping, with the same force, will not make it move any further. At this point, the sound of the tapping will also change. If these signs of primary stability are not observed, the prosthesis is not stable and there will be a risk of subsidence after surgery. Fig. 20 : The modular head of the prosthesis is firmly fixed on the neck taper of the prosthesis, and then reduced into the socket.

Fig. 21 : The lid of the transfemoral approach, which often tends to stay at the anterior aspect of the prosthesis, is reduced to the lateral aspect of the implant, and secured with sutures, if necessary. The two parts of the greater trochanter are reattached and fixed with heavy sutures. Bony healing at this site is not a problem, because the longitudinal tension structures have been preserved and the greater trochanter has been split lengthwise. Fig. 22 : The fascia lata is tightly closed over suction drains. The postoperative management is identical to that after primary total hip replacement.

Clinical case:
A. Aseptic loosening of a long-stem prosthesis of the left hip, with major bone loss, in a female age 71. B. Immediately after revision arthroplasty using a transfemoral approach. C. 2 years and 5 months after revision, extensive bone repair has taken place; hip function is normal.

CONCLUSION
The transfemoral approach in total hip revision arthroplasty provides ample and excellent exposure of the implants, the bone cement, and the granulomatous tissue, and thus facilitates the surgical procedure, saves operating time, and prevents excessive blood loss. The acetabular component can be revised through the same approach. Uncontrolled fractures and bone perforations in the defective femoral segment can be avoided, and bone repair is greatly stimulated.

| Orthopaedic |


Fig. 3 : Posterolateral skin incision.		Fig. 4 : After longitudinal incision of the fascia lata, the vastus lateralis muscle is exposed.

Fig 5 : A Steinmann pin is inserted at the tip of the greater trochanter (reference point). From this pin, the preplanned length of the transfemoral approach is measured in a distal direction; a second pin is inserted at that point.		Fig. 6 : At the distal end of the transfemoral approach, a mark is made on the bone with a flat osteotome. Only at this point is the muscle released from the bone surface.


Fig. 7 : A drill hole is made at the posterior limit of the semicircular transverse osteotomy.		Fig. 8 : Tha vastus lateralis muscle is carefully released from the lateral intermuscular septum. In a proximal direction from the drill hole, the longitudinal osteotomy is made along the linea aspera with sharp flat osteotomes, without violating the muscle. The osteotomy is routed toward the tip of the greater trochanter, where the proximal Steinmann pin is still in place.

Fig. 9 : After having made a drill hole at the anterior limitation of the transverse osteotomy, flat osteotomes are inserted between the muscle fibres, and discontinuous puncture osteotomies are made from the anterior drill hole in a proximal direction for the anterior border of the lid. The distance between the two drill holes determines the width of the lid.		Fig. 10 : The posterior longitudinal osteotomy is carefully opened with chisels and fragment spreaders, and the cement mantle of the femoral prosthesis is exposed over its entire length.

Fig. 11 : After resection of the scar tissue around the neck of the prosthesis, the implant can be easily removed.		Fig. 12 : With further displacement of the two pieces of the greater trochanter, spike retractors can be placed around the acetabular rim exposing the acetabular component over its entire circumference.


Fig. 13 : After removal of the polyethylene insert, the PMMA cement is cut into pieces to facilitate its removal and to prevent damage to the bony acetabulum.		Fig. 14 : After careful debridement of the acetabular cavity and application of bone grafts to the defects, an uncemented acetabular component is inserted and firmly fixed.

Fig. 15 : Distal to the transverse osteotomy of the transfemoral approach, the medullary cavity is reamed with conical reamers to create a conical seat for the conical stem of the revision prosthesis. Due to the cone angle of 2(infinity), only very little bone needs to be removed. The depth of insertion of the reamer is measured and compared with the preoperative planning. Reaming must be continued until a strong frictional resistance is encountered and the depth of insertion of the reamer corresponds to the planned value. If, in soft bone, the reamer penetrates further, a thicker stem diameter must be used. Therefore, the final choice of the implant diameter should not be made before reaming is completed; also, the sterile prosthesis should not be unpacked before that stage. When the reamer is retracted from the medullary cavity, fine bone shavings sticking to the sharp edges will indicate the extent of the conical cavity. Distally to the transverse osteotomy, a double cerclage with 1.5 mm diameter stainless steel wire may be applied if necessary.		Fig. 16 : The bone shell of the old implant bed is carefully curetted immediately prior to the insertion of the implant. This is not done any earlier, in order to minimize bleeding.


Fig. 17 : The femoral revision prosthesis is pushed into the medullary cavity with the impactor/retractor. Firm resistance will be encountered ca. 10-15 mm before the final position has been reached.		Fig. 18 : A slotted hammer is placed on the shaft of the impactor/retractor, and the rotational position is checked with the limb at 90(infinity). In a left hip (example in this figure) counter-clockwise rotation increases the angle of anteversion, in a right hip vice versa.


Fig. 19 : A goniometer may also be used if desired. Then the prosthesis is impacted with only moderate tapping, just to give enough stability for a trial reduction. Firm impaction should be avoided at this point, so that the prosthesis can be easily mobilized if rotational correction becomes necessary. A short trial head is placed on the neck of the prosthesis, because the implant is not completely impacted and therefore "relatively too long". After reduction, the stability of the prosthetic joint is checked in flexion and internal rotation. Additionally, 10 kg longitudinal traction is applied to the straight leg: If the joint opens more than 8 mm, a longer modular head must be used. If a rotational correction becomes necessary, which may depend also on the position of the acetabular component, the prosthesis is redislocated and mobilized with the impactor/retractor and the slotted hammer, and the rotational correction is carried out. Another trial reduction must then be performed. For the final firm impaction of the revision prosthesis, regular tapping is applied to the impacting instrument. With every tap, the prosthesis will move a few millimeters distally, which can be seen clearly at the edge of the transverse osteotomy. Tapping is continued until the migration of the implant stops and continued tapping, with the same force, will not make it move any further. At this point, the sound of the tapping will also change. If these signs of primary stability are not observed, the prosthesis is not stable and there will be a risk of subsidence after surgery.		Fig. 20 : The modular head of the prosthesis is firmly fixed on the neck taper of the prosthesis, and then reduced into the socket.

Fig. 21 : The lid of the transfemoral approach, which often tends to stay at the anterior aspect of the prosthesis, is reduced to the lateral aspect of the implant, and secured with sutures, if necessary. The two parts of the greater trochanter are reattached and fixed with heavy sutures. Bony healing at this site is not a problem, because the longitudinal tension structures have been preserved and the greater trochanter has been split lengthwise.		Fig. 22 : The fascia lata is tightly closed over suction drains. The postoperative management is identical to that after primary total hip replacement.


Clinical case: A. Aseptic loosening of a long-stem prosthesis of the left hip, with major bone loss, in a female age 71.	B. Immediately after revision arthroplasty using a transfemoral approach.	C. 2 years and 5 months after revision, extensive bone repair has taken place; hip function is normal.