Abstract. Introduction. Derby technique for posterolateral corner (PLC) reconstruction uses a doubled gracilis autograft to reconstruct the popliteo-fibular ligament (PFL) and a split biceps tendon transfer to reconstruct the lateral collateral ligament (LCL). We report midterm outcomes of a case series who underwent PLC reconstruction. Methodology. A retrospective review of 27 patients who underwent PLC reconstruction from 2012 until 2018 was performed (6 females, 21 males, median age 26). Median time interval from injury to primary procedure was 10 months. Outcomes were recorded as per clinical assessment and outcome scores. Results. All patients had no varus laxity in full knee extension. Similarly, at 30° of knee flexion, 25 patients (92.5%) had no varus laxity and 2 patients (7.5%) had grade 1 laxity. No patients demonstrated abnormal external rotation at final follow up. Outcome scores were obtained from 17 patients who underwent primary ligament reconstruction at a mean follow up of 72 months postoperatively. The mean Lysholm score was 94 +/-5.5 (72–100) and mean subjective IKDC score was 78/87 (89.6%) (51–87). 90% of our patients had gained normal or nearly normal IKDC scores on returning to routine activities of daily living and sports following surgery compared to their pre-injury status. Conclusion. Our technique enables an anatomical LCL & PFL reconstruction in isolation or in combination with ACL/PCL reconstruction or to augment an acute repair without contralateral graft harvest or allograft. The functional knee scores demonstrated in this cohort are comparable and in fact superior to previously published knee scores after PLC reconstruction

The management of osteoarthritis of the knee associated with patellar instability secondary to external tibial torsion > 45° is challenging. Patellofemoral biomechanics in these patients cannot be achieved by intra-articular correction using standard techniques of total knee replacement.

We reviewed seven patients (eight knees) with recurrent patellar dislocation and one with bilateral irreducible lateral dislocation who had undergone simultaneous total knee replacement and internal tibial derotational osteotomy. All had osteoarthritis and severe external tibial torsion. The mean follow-up was for 47.2 months (24 to 120).

The mean objective and functional Knee Society scores improved significantly (p = 0.0001) from 29.7 and 41.5 pre-operatively to 71.4 and 73.5 post-operatively, respectively. In all patients the osteotomies healed and patellar stability was restored.

Excessive external tibial torsion should be identified and corrected in patients with osteoarthritis and patellar instability. Simultaneous internal rotation osteotomy of the tibia and total knee replacement is a technically demanding but effective treatment for such patients.

Injury to the common peroneal nerve was present in 14 of 55 patients (25%) with dislocation of the knee. All underwent ligament reconstruction. The most common presenting direction of the dislocation was anterior or anteromedial with associated disruption of both cruciate ligaments and the posterolateral structures of the knee. Palsy of the common peroneal nerve was present in 14 of 34 (41%) of these patients. Complete rupture of the nerve was seen in four patients and a lesion in continuity in ten.

Three patients with lesions in continuity, but with less than 7 cm of the nerve involved, had complete recovery within six to 18 months. In the remaining seven with more extensive lesions, two regained no motor function, and one had only MRC grade-2 function. Four patients regained some weak dorsiflexion or eversion (MRC grade 3 or 4). Some sensory recovery occurred in all seven of these patients, but was incomplete. In summary, complete recovery occurred in three (21%) and partial recovery of useful motor function in four (29%). In the other seven (50%) no useful motor or sensory function returned.