CHAPTER 59 • KNEE INSTABILITY 355ligament (LaPrade and Wentorf, 2002). Most often,
these are injured in combination with either the PCL
(most common) or ACL and should be repaired at the
time of the cruciate repair. The mechanism of injury is
generally a blow to the anteromedial aspect of the
knee, hyperextenion, or a varus noncontact injury
(LaPrade and Terry, 1997).- External rotation recurvatum, posterolateral drawer
test, reverse pivot shift test, and examination for
increased external rotation are all important compo-
nents of the physical examination. Peroneal nerve
function should also be assessed, as 15% of postero-
lateral corner injuries have concomitant injury to the
common peroneal nerve (LaPrade and Terry, 1997).
MRI scans may be valuable in assessing what struc-
tures are involved in the injury. - Because of poor results with chronic reconstruction,
acute repair is advocated in Grade III posterolateral
corner injuries within 1–2 weeks if possible. One of
the more popular techniques for repair is the popliteus
tendon and popliteofibular ligament reconstruction
(Veltri and Warren, 1995).
MULTIPLE LIGAMENT INJURIES
- Knee dislocations leading to multiple ligament
injuries are fortunately relatively rare. Oftentimes,
knee dislocations lead to tears of both the ACL and
PCL as well as supporting ligamentous structures of
the knee. Nerurovascular injury is often present, and a
thorough examination must be performed. Popliteal
artery injury occurs in approximately 1/3 of knee dis-
locations (Cole and Harner, 1999). Early arteriogra-
phy is advocated to avoid missing potential popliteal
artery injuries, as such injuries can lead to ischemia
and require eventual amputation.
•Nerve injury is also quite common in knee dislocations.
Peroneal nerve injury occurs in between 9 and 49% of
knee dislocations (Shields, Mital, and Cave, 1969; Taft
and Almekinders, 1994), and tibial nerve damage has
also been reported (Welling, Kakkasseril and Cranley,
1981). Additionally, as a result of their traumatic nature,
knee dislocations frequently have associated fractures. - Knee dislocations are described by the relative posi-
tion of the tibia to the femur. Dislocations can be ante-
rior, posterior, medial, lateral, or a combination of
these (rotatory). Anterior dislocations are seen with
extreme hyperextension, and posterior dislocations
may result from high impact dash-board type injuries
(Cole and Harner, 1999). Knee dislocations can spon-
taneously relocate.
•Immediate surgical management is required for
popliteal injuries, open dislocations, irreducible
dislocations, and compartment syndrome. Ligament
reconstruction is generally delayed for 1 to 3 weeks
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