FROSCH POSTEROLATERAL APPROACH KNEE

INTRODUCTION 

* At least 7% of all tibial plateau fractures lie in the region of the posterolateral corner. Fractures in this region, usually cannot be adequately treated by using a lateral or anterolateral approach due to coverage by the fibular head and ligamentous structures in the corner region of the popliteus muscle. 

• To minimize this problem, a lateral approach  was described by Lobenhoffer et al.With this approach, a fibular osteotomy and detachment of the joint capsule and meniscotibial ligaments from the lateral tibial plateau  allow for the exposure and examination of the posterolateral joint surfaces of tibia. 

• Lobenhoffer approach provides a good view of the posterolateral corner of the tibial plateau but leads to extensive trauma of soft tissue there.

• Isolated posterior approaches allow for fragment fixation but visual control of fracture reduction is limited. 

* Therefore a modified surgical technique for the treatment of posterolateral tibial plateau fracture was introduced. Frosch described this posterolateral approach for fracture reduction and fixation combined with a lateral arthrotomy to visually control the fracture alignment and the joint surface. 

SURGICAL TECHNIQUE- 

 POSITION- 

• Patient lies in a lateral position. 

• Knee is supported by thick rolled pillow because the weight of the leg itself apply varus stress which causes the joint gap to be laterally opened. 

INCISION-

• An approximately 15 cm long posterolateral skin incision is required. Fibula head is used as an anatomical landmark. 

•Incision starts 3 cm above the joint line and follows the fibula in a distal direction. 

•Before the popliteal fossa is dissected a lateral standard arthrotomy is performed.

EXPOSURE- 

•The iliotibial tract is incised from the dorsal side and the dorsal fibers are detached from the Gerdy's tubercle. Thereafter, the lateral capsule is incised and the meniscotibial ligament is dissected approximately 2mm away from its insertion in the tibia, parallel to the joint surface.

•The entire lateral tibial plateau, including the posterolateral corner can be viewed by using this lateral arthrotomy. 

•For manipulation of the posterolateral fragment an additional posterolateral exposure of the fragments is necessary.

• Both approaches are performed through one skin incision. 

• After direct incision of the fascia, the peroneal nerve is exposed to the rear edge of the biceps femoris muscle. The nerve should be carefully dissected and gently mobilized for protection during the operation. 

• Blunt dissection of the popliteal fossa is initially performed between the lateral head of gastrocnemius and soleus and inspection begins on the muscle belly of soleus. 

• Popliteal vessels and the popliteus muscle are exposed.The popliteal vessels are protected by the lateral head of gastrocnemius which is retracted by a Langenbeck retractor. 

•Inferior genicular vessels are ligated only if necessary. 

•At distal edge of the popliteal muscle, it is pulled back towards the medial and cranial direction. Then the muscle is carefully detached from the dorsal surface of the fibula. 

•The soleus muscle  should be detached distally until the peroneal nerve at the fibular neck enters into the musculature. The peroneal nerve should not be detached after it enters into the musculature because muscle branches leading off in a atypical fashion can be easily damaged.

FIXATION- 

•Posterolateral fragments are manipulated and reduced from the dorsal side with a raspatory or with pointed reduction forceps. 

•Fragments after reduction are held in place using K wires. 

•Plain radiographs need to be performed intraoperatively. 

*After fracture reduction, a conventional radius, T plate can be pinched off with lateral gutters so that a two-hole L-plate is obtained. To buttress the fracture, the plate can be slightly under countered and dorsally fixed with conventional screws. 

The lateral edge of the plate lies immediately next to the fibular Head.

ADVANTAGES- 

1) Visual control of the reduction of the fracture is achieved through a conventional lateral standard arthrotomy, which is accomplished through the same skin incision. The anatomical reduction of the fracture and internal fixation are performed from the dorsal side. Therefore as a result of the modified posterolateral approach, the fragments are not denuded. 

2) The avoidance of fibula osteotomy in most patients with posterolateral tibial plateau fractures is an advantage. 

3) Damage to the upper tibiofibular joint and nerve injuries caused by an oscillating saw blade can be avoided by using the presented technique. 

4) Minimal soft tissue damage compared to Lobenhoffer posterolateral approach with fibular osteotomy. 

Limitation of the modified posterolateral approach - 

 1) It cannot be extended distally because of the trifurcation vessels that traverse the interosseous membrane approximately 5 cm below the joint line. However, because the lateral tibial metaphysis has a posterior inclination angle of approximately 45 degree and the posterolateral split fracture segment is usually less than 4 cm in cortical length, this limitation seems to have no problem in practice. 

2) Difficult to address additional medial plateau fractures when the patient is lying in the lateral position. 

3) Iatrogenic injuries of blood vessels can occur if the posterolateral plate is placed too far distally. 

4) Precise knowledge of the anatomy of the posterolateral corner is required. 

REMPLISSAGE PROCEDURE

The term 'Remplissage' means  'to fill in'.

• 1st described in 2007 by Wolf et al (1) as an adjunct to the arthroscopic anterior stabilisation procedure of the shoulder in order to address a large engaging Hill-

Sach's defect. 

•This technique has been reported to be effective in reducing the incidence of recurrent anterior shoulder instability, when used along with arthroscopic Bankart repair .

Indication- 

• This technique is performed when the Hill-Sachs lesion is very large and engaging the anterior glenoid with little overhead movement (i.e. dislocating very easily due to the large Hill-Sachs lesion, as well as the Bankart lesion). In these situations a Bankart repair alone may not be sufficient. Thus the development of the remplissage technique.

Operative Technique- 

 • The arthroscope is placed through the anterior portal to view the Hill-Sach's lesion on the posterior aspect of the

humeral head. Through the posterior portal, a burr is introduced to decorticate the Hill-Sach's lesion. 

• A triple-loaded large rotator cuff anchor is inserted into the Hill-Sach's defect through

the posterior portal. 

• Sutures are passed through the infraspinatus tendon and the posterior

capsule, which are then tied down with a 'parachute technique', hence successfully filling the defect on the humeral head.

Advantages - 

• The ability to make the Hill-Sach's defect

extra-articular, thereby eliminating engagement of the defect with the anterior glenoid rim. 

• It is ideally suited to instability patients who have large, engaging Hill-Sachs lesions and soft-tissue Bankart tears. These patients are known to have a higher failure rate after surgery than those with smaller lesions. The results of this technique in this difficult subset of traumatic anterior shoulder instability patients are significantly better (10% recurrence rate) than with an

arthroscopic Bankart repair alone (67% recurrence rate). 

Forearm and Wrist Fractures Eponym

Barton f.: an intraarticular fracture of the dorsal rim of the distal radius, usually resulting in subluxation of the radial carpal joint with the fracture site fragment.

chauffeur's f.: oblique fracture of the radial styloid caused by a twisting- or snapping-type injury; also called backfire f., Hutchinson f., and lorry driver's f.

chisel f.: incomplete, usually involving medial head of radius, with fracture line extending distally.

Colles f.: named prior to x-ray technology; implies a fracture of the distal radius, either articular or non-articular, with dorsal angulation of the distal fragment producing a silver fork deformity; generally associated with a fracture of the ulnar styloid.

Corner f.: a small bucket-handle-appearing fracture in the distal metaphyseal corner in a young child, often associated with child abuse.

de Quervain f.: combination of a wrist scaphoid fracture with volar dislocation of scaphoid fragment and lunate.

die-punch f.: an intraarticular fracture of the ulnar (volar) portion of the distal radius, usually caused by direct impaction of the lunate onto the lunate fossa of the distal radius.

Essex-Lopresti f.: a comminuted ¹radial head fracture with an injury to the ²distal radioulnar joint caused by disruption of the ³interosseous membrane, which can cause a proximal migration of the radius if the radial head is excised secondarily.

Galeazzi f.: typically a displaced fracture of the distal third or quarter of the radius with disruption of the distal radioulnar joint; called fracture of necessity because surgical fixation is required for reduction; also called a reverse Monteggia f., Dupuytren f., or Piedmont f.

Kocher f.: fracture of capitellum of distal humerus with possible displacement of fragment into joint.

Laugier f.: isolated fracture of the trochlea of the humerus at the elbow.

lead pipe f: typically in the forearm, a combination of greenstick fracture and torus fracture in the immature skeleton. Such fractures do not penetrate the entire shaft of the bone and have the appearance of a slightly bent lead pipe.

Lenteneur's f.: a distal radial fracture of the palmar rim, similar to Smith's type II fracture.

Monteggia f.: isolated fracture of proximal third of ulna, with anterior or posterior or lateral dislocation of radial head allowing angulation and overriding of ulnar fragments.

Moore f.: like a Colles f.; specifically, fracture of distal radius with dorsal displacement of ulnar styloid and impingement under annular ligament.

Mouchet f.: involves humeral capitellum.

Nightstick f.: undisplaced fracture of the ulnar shaft caused by a direct blow.

Piedmont f.: oblique f. usually at the proximal portion of distal third of the radius; obliquity runs from proximal ulnar to distal radial aspect, allowing distal fragments to be pulled into the ulna by the pronator quadratus muscle; fracture of necessity requiring

operative management.

Radial head f.: involves the most proximal part of the radius, a dish-shaped portion of bone.

radial styloid f.: involves distal radial tip of radius.

reverse Barton f.: dorsal displacement of carpus on radius, with associated fracture of dorsal articular surface of radius. The mechanism and appearance of this fracture are similar to those of a Colles f.

Skillern f.: open f. of distal radius associated with greenstick f. of distal ulna.

Smith f.: fracture of the distal radius in which the distal fragment is displaced volarly; also called reverse Colles f. This fracture was defined before the advent of radiography, and, classically, there are three types:

•Nonarticular

•Intraarticular; also called volar Barton f.

•Oblique nonarticular fracture near the joint line. 

Implants Q & A

 1)BIODEGRADABLE IMPLANTS 

•Metallic osteosynthetic devices have been extensively used worldwide.

•However there are inherent problems with the use of these metallic devices like stress shielding phenomenon, pain, local irritation etc.

•Retained metallic implants are always at the risk of endogenous infection.

•Release of metallic ions from these implants has been documented, though the long term effects of these are not yet known.

•Because of these reasons there is always need for a second surgery for implant removal after the bone has healed.

•The reasons mentioned above led to the evolution of biodegradable implants aiming toward true biologic solutions to reconstructive problems.

•Biodegradable implants are derived by transforming compounds that are present in nature to structural plastics.

•Organic molecules are polymerized to form strong fibers and solid compounds.

•When these polymers are implanted in patients, they degrade and are eliminated from the body in a  period of time.

STRUCTURE, STRENGTH AND PROPERTIES

• Widely used biodegradable materials include polyglycolic acid (PGA), poly-L- lactic acid (PLLA), poly-DL-lactic acid (PDLLA), PGA/trimethylene carbonate compolymers (PGA/TMC), and poly-beta-

hydroxybutyric acid (PBHBA).

• Polyglycolic acid (PGA) is a hard, tough, crystalline polymer with an average molecular weight of 20,000 to 145,000 and a melting point of 224-230°C.

• Polylactic acid on the other hand is a polymer with initial molecular weights of 180,000 to 530,000 and a melting point of about 174°C .

• In orthopaedic implants poly-L-lactic acid (PLLA) has been used more extensively because it retains its initial strength longer than poly-D-lactic-acid (PDLA).

•PGA belongs to the category of fast degrading polymers, and intraosseously implanted PGA screws have been shown to completely disappear within 6 months.

• PLLA on the other hand has a very long degradation time and has been shown to persist in tissues for as long as 5 years post implantation.

• For Orthopaedic usage, the main hindrance to development of bioabsorbable implants has been the question of obtaining sufficient initial strength and retaining this strength in the bone.

• With the use of self reinforcing (SR) technique the material was sintered together at high temperature and pressure, resulting in initial strengths 5 to 10 times higher than those implants manufactured with melt moulding technique.

•Though initial strengths of SR-PLLA screws are lower than SR-PGA, strength retention in the former is longer than the latter.

•Now a days, bioabsorbable implants show no difference in the stiffness, linear load & failure mode when compared with metallic devices.

• PGA is sterilized with ethylene oxide and PLA with gamma irradiation.

ADVANTAGES

•The biggest advantage is that since these implants have the potential for being completely absorbed, the need for a second operation for removal is overcome and long-term interference with tendons, nerves and the growing skeleton is avoided.

•Additionally, the risk of implant-associated stress shielding, peri-implant osteoporosis and infections is reduced.

•An important aspect is that these implants do not interfere with clinical imaging.

• This allows the use of modalities like MRI in knee and shoulder injuries at any stage after surgical implantation.

The other advantages include biodegradability of implants placed across mobile articular surfaces, as plus acceptable biocompatibility and resorption properties that reduces concern about complications.

• Bioabsorbable implants, due to the fact that they may resorb inside tissues, offer specific

advantages in specific fracture fixations; in the foot and ankle, where removal of the hardware is often mandatory prior to mobilization, they maybe beneficial in syndesmotic disruptions and Lisfranc's dislocations.

CURRENT USES

•Biodegradable implants are available for stabilization of fractures, osteotomies, bone grafts and fusions particularly in cancellous bones, as well as for reattachment of ligaments, tendons, meniscal tears and other soft tissue structures.

•The mechanical properties of the materials permit them to be used with metaphyseal and peri-

articular fractures where the loading is relatively low.

• Therefore, they have mainly been used for treating small-bone fractures such as ankle fractures

•Another suitable anatomic area for application is the elbow joint.

•They may be used for fixing fractures of the radial head, olecranon, capitellum and distal humerus.

•Nonetheless, comminuted fractures in these locations are not good candidates.

•Other conditions for which these implants can be used are fractures of the distal radial styloid, patella, glenoid fossa and acetabulum; osteochondral fractures in the knee, tibial plateaux, phalanx, calcaneus and talus; and also hallux valgus surgery.

•Biodegradable screws or rods may also be used for treating epiphyseal fractures.

•These have been used extensively for ACL reconstruction in the form of interference screws and transfixation screws.

•Meniscal tacks and biodegradable suture anchors have opened new avenues for soft tissue reconstruction in complex knee injuries.

•Biodegradable implants provide viable options for the repair and reconstruction of many intra-articular and extra-articular abnormalities in the shoulder, including rotator cuff tears, shoulder instability, and biceps lesions that require labrum repair or biceps tendon tenodesis.

•In spine surgeries, Bioresorbable implants can be used as interbody spacers in lumbar interbody fusion

•Bioabsorbable anterior cervical plates have been used and studied as alternatives to metal plates when a graft containment device is required. 

DEGRADATION

•Crystalline polymers have a regular internal structure and because of the orderly arrangement are

slow to degrade.

•Amorphous polymers have a random structure and are completely and more easily degraded

•Semi-crystalline polymers have crystalline and amorphous (random structure) regions.

•Hydrolysis begins at the amorphous area leaving the more slowly degrading crystalline debris

•Polyglycolide (PGA), is hydrophilic and degrades very quickly, losing virtually all strength within one

month and all mass within 6-12 months.

•Adverse reactions can occur if the rate of degradation exceeds the limit of tissue tolerance.

•So PGA in isolation is rarely used these days in the manufacture of bioabsorbable implants.

•Poly L Lactic Acid (PLLA), has a much slower rate of absorption.

• This is highly crystalline & has been documented to take more than five years to absorb.

• The ideal material is perhaps one that has a "medium" degradation time of around 2 years, as by that time the purpose for which the implant was put has been served.

DISADVANTAGES

•There are quite a few problems that need to be addressed with the use of these devices.

• Primarily the inadequate stiffness of the device and weakness compared to metal implant can pose implantation difficulties like screw breakage during insertion and also make early mobilization precarious.

•The other potential disadvantages are an inflammatory response described with bioabsorbable implants, rapid loss of initial implant strength and higher refracture rates.

• Problem areas of concern regarding faster resorbed implants are due to the fact that the body mechanisms are not able to clear away the products of degradation, when they are produced at a faster rate.

• This may lead to a foreign body reaction.

FUTURE

• Covalent linking of compounds such as HRP, IL-2, and BMP-2 to plates represents a novel method for delivering concentrated levels of growth factors to a specific site and potentially extending their half-life.

•BMP-2 covalently linked to resorbable plates has been used to facilitate bone healing.