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through the Kocher-langenbeck Approach.
Tips and Tricks.
FRÉDÉRIC LAUDE
Clinique des Lilas - 93260 Les Lilas
Hôpital de la Pitié - 75013 Paris - France
The posterior Kocher-Langenbeck approach is probably the best-known and the easiest incision for the management of acetabular fractures. However, the reduction of acetabular fractures through this approach is not altogether straightforward, since the exposure provided is limited, and the proximity of vital structures makes some of the manipulations involved in the reduction dangerous (Fig. 1). This article recalls some of the basic principles of the management of acetabular fractures through the Kocher-Langenbeck approach.
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| Figure 1: Blue areas = access by touch; yellow areas = visual access |
| INSTRUMENTS AND IMPLANTS |
For acetabular surgery, certain special instruments are required, which greatly facilitate the reduction of the fracture fragments.
The joint is deep, and the fragments are, therefore, difficult to mobilize. The ball-spike instrument named “picador” by Emile Letournel is a modified bone awl that allows fragments to be pushed or held in place. A small (Lambotte) bone hook makes it possible to pull on and to mobilize fragments (e.g. a posterior column at the sciatic notch).
The manoeuvre of mobilizing an entire column may be accomplished with a Schanz screw fitted in a T-handled chuck, or a “corkscrew” femoral head extractor. This tool is screwed into the ischium, and allows the posterior column or the distal portion of a transverse acetabular fracture to be readily manipulated. It may also be screwed into the greater trochanter, to effect the lateral traction required for the reduction of some fractures (Fig. 2). This lateral traction may also be provided via a bracket on the Judet table, thereby releasing an assistant for other duties. Also, a sterile Velpeau bandage may be tied around the assistant’s or the operating surgeon’s waist, with the other end attached to the corkscrew, to provide strong and even traction.
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| Figure 2: “Corkscrew” extractor, and Picador ball-spike |
Special bone holding forceps make reduction very much easier. Modified Farabeuf forceps come in a number of sizes, and can be applied to screw heads left proud on either side of the fracture line, to hold the main fragments together. These forceps constitute a very important means of maintaining reduction. The clamps developed by Joel Matta are also very useful. Matta clamps are available in two sizes. Their jaws are very slender, and can be introduced through the greater sciatic notch without damaging the sciatic nerve (Fig. 3).
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| Figure 3: Matta clamps, and Farabeuf forceps |
Emile Letournel used to fold over the medial skin flap and suture it to the surrounding skin at the start of the procedure, so as to dispense with the need for manual retraction during surgery. For optimum exposure through a Kocher-Langenbeck incision, a sciatic nerve retractor is invaluable. Its tip is placed into the bursa in the lesser sciatic notch where the obturator internus muscle pulleys over the bone, care being taken to ensure that the tension is released at frequent intervals, so as not to damage the sciatic nerve (Fig. 4).
Long ribbon retractors, and malleable blades, are also useful aids to exposure.
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| Figure 4: Sciatic nerve retractors |
The hardware is specifically designed for the management of acetabular fractures. The intricate shape of the hip bone makes it necessary to have curved plates that can be contoured lengthwise as well as on the flat. Preformed plates are not very useful, and may, in fact, do harm. The plate must mould itself to the bone, and not vice versa. The curved plates used in acetabular surgery are generally supplied with two curvatures: 88° and 108°. The plate bending tools supplied by Osteo and by the AO are particularly efficient for the contouring of the plates (Fig. 5).
Flexible templates are available, and may be useful in the preparation of the plates.
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| Figure 5: Multi-purpose plate bending tool |
Drills must be available in several diameters; the drill bits used for this kind of surgery are substantially longer than those used for other procedures. An oscillating drill is a great help, since it prevents damage to adjacent tissues.
The instruments described above make surgery very much easier; however, no tool is better than its user. In acetabular surgery, experience and meticulous preoperative planning are absolutely essential.
| INDICATIONS OF THE KOCHER-LANGENBECK APPROACH |
The following fractures are always accessed through a Kocher-Langenbeck approach:
- Posterior wall fractures (Fig. 6a);
- Posterior column fractures (Fig. 6b);
- Posterior column plus posterior wall fractures;
- Juxtatectal or infratectal transverse fractures (Fig. 6c).
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| Figure 6a: Posterior wall fracture | Figure 6b: Posterior column fracture | Figure 6c: Transverse fracture |
The following fractures may be accessed through a Kocher-Langenbeck approach:
- Transverse fractures through the acetabular roof. However, a lateral approach will often be preferred.
- T-shaped fractures, especially if the anterior column is not excessively displaced. Where difficulties are encountered, a large lateral approach is often preferred (Fig. 6d).
- Low both-column fractures that do not involve the iliac wing (Fig. 6e).
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| Figure 6d: T-shaped fracture | Figure 6e: Low both-column fracture |
The following fractures are never accessed through a Kocher-Langenbeck approach:
- Both-column fractures;
- Anterior column fractures;
- Anterior column plus posterior hemitransverse fractures.
| POSTERIOR WALL FRACTURES |
This is the easiest fracture pattern to manage with acetabular surgery. The incision should be as atraumatic as possible. The fragment is usually found displaced in the short external rotators, which prevent its spontaneous reduction. If the capsule is torn, the fragment will usually be held by the periosteum and by the posterior muscle attachments. The femoral head and the hip joint are readily seen. If the joint capsule is attached to the wall fragment, the femoral head must have dislocated into the fracture site. In such cases, there will frequently be cartilage impaction. The approach of the posterior wall must be such as to preserve as much as possible the surrounding structures and the blood supply to the wall. Posterior wall necrosis frequently results in early post-traumatic osteoarthritis. This complication is often caused by a somewhat overaggressive surgical approach. The approach to the joint should therefore follow the path taken by the femoral head.
Traction is applied (preferably for a period not exceeding 3 minutes), and the joint is rinsed and debrided of organizing clot and of the remaining ligament of the head of the femur. A careful search should be made for damage to the femoral head cartilage.
If the cartilage has been impacted, the defects should be elevated and grafted. The bone used for grafting should be harvested from the greater trochanter rather than from the iliac crest (Fig. 7a-d).
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| Figure 7a,b,c: Elevation and grafting of posterior wall fracture with articular impaction | ||
Once reduction has been achieved, it is held with two lag screws (Fig. 8). A five- or six-hole plate is moulded to the reduced wall, for buttressing (Fig. 9). Screw fixation without plating may result in the early failure of the construct. Fracture patterns involving a large number of fragments may be extremely difficult to reduce perfectly.
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| Figure 8 : Screw insertion after reduction ... | Figure 9: ... followed by plating. |
In comminuted fractures, the spring plates devised by Jeff Mast may be helpful. A small quarter-tube AO plate is cut in two across a hole. The prongs are bent back to form two small hooks, which will hold small fragments that cannot be fixed with screws (Fig. 10a, b).
 Figure 10 : A quarter-tube plate is cut across a hole. The two prongs are bent down to create small hooks. Use of spring plates in a comminuted fracture. |
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It is vital to ensure that the screws are placed in the hip bone, without protruding into the joint or into the pelvis. Screw placement within 10 mm of the joint exposes to the risk of intra-articular penetration. Beyond the danger zone of 10 mm (one finger breadth), the screw tract must be angled posteriorly, and never be at right angles to the wall. A small 10 mm K-wire may be placed in the joint, tangential to the cartilage, to mark the danger zone (Figs. 11, 12).
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| Figure 11 : Red area = danger zone | Figure 12 : Insertion of a K-wire in the joint, tangential to the cartilage. This wire marks the danger zone. |
| POSTERIOR COLUMN FRACTURES |
As stated above, the approach to the fracture site must be as atraumatic as possible. In the interest of rapid recovery and the prevention of postoperative heterotopic bone formation, the blood supply to the tissues must be preserved. The hip joint and the bone fragments must be debrided of organizing clot that could get into the fracture site and interfere with reduction. Méary forceps may be used to open up the fracture line. If reduction proves difficult, these forceps may also be used to mobilize a periosteal hinge.
For reduction, the posterior column usually needs derotating. Mobilization is performed using a Schanz screw placed in the ischium. This is used like a joystick to joggle the entire column (Fig. 13). Reduction is checked by visual inspection, and by passing a finger through the greater sciatic notch to feel the fracture site from the back of the quadrilateral plate.
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| Figure 13 : Posterior column reduction with a Schanz screw | Figure 14 : Reduction with a Farabeuf clamp applied to two screw heads |
Once reduction has been achieved, it may be maintained with two screws placed on either side of the fracture line, and a Farabeuf clamp applied to the screw heads (Fig. 14). Fixation is provided by a six-hole plate plus either a small four-hole plate or a screw to lag the fracture (Fig. 15).
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| Figure 15 : Fixation patterns in posterior column fractures |
| POSTERIOR COLUMN PLUS POSTERIOR WALL FRACTURES |
This pattern is treated along the same lines. Very often, the posterior column will be found to be but little displaced, and reduction will be difficult to obtain. Virtually always, the posterior wall will be attached to the joint capsule. As stated above, this structure must be protected.
Cartilage impaction on the posterior column must be checked for.
The posterior column is reduced first; any depressed cartilage is elevated; and the posterior wall is reduced.
| TRANSVERSE ACETABULAR FRACTURES |
Reduction requires an understanding of the displacement dynamics. The displaced structure is the distal fragment. The pubic symphysis is the pivot around which the distal fragment rotates. In addition, there is rotation around an axis that runs through the fracture plane. This is why, as a rule, displacement is very much greater in the posterior column (Fig. 16). Reduction through a Kocher-Langenbeck incision is, therefore, a sensible option.
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| Figure 16 : Rotational component of transverse fractures |
If the fracture is through the acetabular roof, just within the weight-bearing zone, reduction must be absolutely perfect. In such cases, it is probably best to use an extended iliofemoral approach, especially in younger patients.
Reduction is usually performed using a Schanz screw placed in the ischium. A visual inspection of the result is made, and - above all - palpation through the greater sciatic notch is used to check the rotation and the correct reduction of the anterior column. In patients with transverse acetabular fractures, there may be pelvic ring injuries. There is almost always trauma to a sacroiliac joint or a fracture involving the obturator ring on one side. These associated lesions may make it very difficult to obtain the reduction of the acetabular fracture; often, special measures will be required (Fig. 17).
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| Figure 17 : In order to achieve a sound construct, the screws used to fix a transverse fracture must cross the fracture line. |
If there is an associated fracture of the posterior wall, the transverse fracture should be reduced first, with the surgeon benefiting from the intra-articular view obtained through the posterior wall fracture.
| T-SHAPED FRACTURES OF THE ACETABULUM |
The reduction of this fracture pattern through a Kocher-Langenbeck incision demands great experience, and should not be attempted by the less experienced surgeon. In younger patients, a lateral approach should be used in preference to the K-L, since a properly performed lateral incision will allow a much better inspection of the reduction.
If the anterior column fracture is low and only slightly displaced, or if it is thought that an extended iliofemoral approach would be too aggressive (e.g. in an elderly patient), the K-L approach is a useful alternative.
The posterior column is reduced first, using a Schanz screw (as in the other patterns) for the manipulation of the distal part of the posterior column. The reduction of the rotational component of the displacement may be very difficult to assess. Once reduction has been obtained, one or two lag screws are inserted to maintain the reduction. The placement of these reduction screws must be carefully thought out, since they must not on any account protrude into the fracture site, where they would make it impossible for the anterior column to be reduced (Fig. 18).
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Figure 18 : If the screws maintaining a posterior column reduction are too long, it may be impossible to reduce the anterior column |
Once the posterior column has been reduced and stabilized, a small bone hook or a Matta clamp is inserted through the greater sciatic notch and placed against the anterior column for reduction. The result is checked by palpation. Next, one or two screws may be inserted parallel with the quadrilateral surface, to hold the reduction. This manoeuvre is much easier to describe than to perform. If anterior column reduction is crucial, a supplementary ilioinguinal approach may be used, under the same anaesthetic, either simultaneously or after repositioning the patient.
| CONCLUSION |
The Kocher-Langenbeck approach makes it possible to manage a large number of acetabular fracture patterns. Any surgeon used to doing hip arthroplasties from a posterolateral approach should find the K-L reasonably straightforward. Surgeons who wish to practise acetabular fracture surgery should use this approach initially, for simple cases, before progressing to the other approaches to the acetabulum.
The point to be borne in mind above all is that, in acetabular surgery, there is no such thing as improvising at surgery. Nothing must be left to chance; everything must be carefully studied on radiographs and scans, and meticulously planned, before surgery. That is the key to success.